sea-weeds, shells and fossils. by peter gray, a.b.s. edin.; and b. b. woodward, _of the british museum (natural history), south kensington._ [illustration] london: swan sonnenschein, le bas & lowrey, paternoster square. butler & tanner, the selwood printing works frome, and london. sea-weeds. by peter gray. algæ, popularly known as sea-weeds, although many species are inhabitants of fresh water, or grow on moist ground, may be briefly described as cellular, flowerless plants, having no proper roots, but imbibing nutriment by their whole surface from the medium in which they grow. as far as has been ascertained, the total number of species is about or , . many of them are microscopic, as the desmids and diatoms, others, as lessonia, and some of the larger laminariæ (oarweeds), are arborescent, covering the bed of the sea around the coast with a submarine forest; while in the pacific, off the northwestern shores of america, nereocystis, a genus allied to laminaria, has a stem over feet in length, which, although not thicker than whipcord, is stout enough to moor a bladder, barrel-shaped, six or seven feet long, and crowned with a tuft of fifty leaves or more, each from thirty to forty feet in length. this vegetable buoy is a favourite resting place of the sea otter; and where the plant exists in any quantity, the surface of the sea is rendered impassable to boats. the stem of macrocystis, which "girds the globe in the southern temperate zone," is stated to extend sometimes to the enormous length of feet. it is no thicker than the finger anywhere, and the upper branches are as slender as pack-thread; but at the base of each leaf there is placed a buoy, in the shape of a vesicle filled with air. although the worthlessness of algæ has been proverbial, as in the "alga inutile" of horace and virgil's "projecta vilior alga," they are not without importance in botanical economics. a dozen or more species found in the british seas are made use of, raw or prepared in several ways, as food for man. of these edible algæ, dr. harvey considers the two species of porphyra, or laver, the most valuable. berkeley says, "the best way of preparing this vegetable or condiment, which is extremely wholesome, is to heat it thoroughly with a little strong gravy or broth, adding, before it is served on toast, a small quantity of butter and lemon juice." a species of nostoc is largely consumed in china as an ingredient in soup. a similar use is made of enteromorpha intestinalis in japan. many species of fish and other animals, turtle included, live upon sea-weed. fucus vesiculosus is a grateful food for cattle. in norway, cattle, horses, sheep, and pigs are largely fed upon it, and on our own coasts cattle eagerly browse on that and kindred species at low water. in some northern countries, fucus serratus sprinkled with meal is used as winter fodder. [illustration: fig. . group of sea-weeds (chiefly laminariæ)] all the marine algæ contain iodine; and even before the value of that substance in glandular complaints had been ascertained, stems of a sea-weed were chewed as a remedy by the inhabitants of certain districts of south america where goître is prevalent. chondrus crispus and (gigartina) mamillosa constitute the irish moss of commerce, which dissolves into a nutritious and delicate jelly, and the restorative value of which in consumption doubtless depends in some degree on the presence of iodine. the freshwater algæ not only furnish abundant and nourishing food to the fish and other animals living in ponds and streams, but by their action in the decomposition of carburetted hydrogen and other noxious gases purify the element in which they live, thus becoming important sanitary agents. the value of aquatic plants in the aquarium is well known. a chinese species of gigartina is much employed as a glue and varnish; and also much used in china in the manufacture of lanterns and transparencies, and in that country and japan for glazing windows. handles for table knives and forks, tools, and other implements have been made from the thick stems of oarweeds, and fishing lines from chorda filum. tripoli powder, extensively used for polishing, consists mainly of the silicious shells of diatoms. on various parts of our coast, the coarser species of sea-weed, now used as a valuable manure, were formerly extensively burnt for kelp, an impure carbonate of soda. this industry, when carried on upon a large scale, became a fruitful source of income to some of the poorest districts in the kingdom, bringing, in the last decade of last century, nearly £ , per annum into orkney alone. since the production of soda from rock salt has become general, kelp is now only burnt for the extraction of iodine, this being the easiest way of obtaining that substance. although the vegetable structure and mode of reproduction are essentially the same in all algæ, as regards the former they vary from the simple cell, through cells arranged in threads, to a stem and leaves simulating the vegetation of higher tribes. and although the simpler kinds are obviously formed of threads, most of the more compound may also be resolved into the same structure by maceration in hot water or diluted muriatic acid. in substance some are mere masses of slime or jelly, others are silky to the feel, horny, cartilaginous or leather-like, and even apparently woody. a few species secrete carbonate of lime from the water, laying it up in their tissues; others cover themselves completely with that mineral, while some coat themselves with silex or flint. many algæ are beautifully coloured, even when growing at depths to which very little light penetrates. as in their vegetative organs, so in their reproductive, algæ exhibit many modifications of structure without much real difference. in the green sea-weeds reproduction is effected by simple cell division in the unicellular species, and by spores resulting from the union of the contents of two cells in the others. the red sea-weeds have a double system of reproduction, a distinctly sexual one, by spores and antheridia, and another by tetraspores, which by some are considered to be of the nature of gemmæ, or buds. the spores are generally situated in distinct hollow conceptacles (favellæ, ceramidium, coccidium). the tetraspore is also sometimes contained in a conceptacle. it consists of a more or less globular, transparent cell, which when mature contains within it four (rarely three) sporules. reproduction in the olive sea-weeds is also double, by zoospores, generally considered gemmæ, and by spores and antherozoids, which is a sexual process. [illustration: fig. . a, species of gleocapsa, one of the palmelleæ, in various stages. a becomes b, c, d, and e by repeated division. magnified diameters.] following the classification adopted by professor harvey, which is that generally employed in english systematic manuals, we divide the order into three sub-orders, named from the prevailing colour of their spores. . chlorospermeæ, with green spores; . rhodospermeæ, with red spores; and . melanospermeæ, with olive-coloured spores. the entire plant in the first group is usually grass-green, but occasionally olive, purple, blue, and sometimes almost black; in the second it is some shade or other of red, very seldom green; and in the third, while generally olive green, it is occasionally brown olive or yellow. the chlorospermeæ are extremely varied in form, often threadlike, and are propagated either by the simple division of the contents of their cells (endochrome), by the transformation of particular joints, or by the change of the contents of the cells into zoospores, which are cells moving freely in water by means of hairlike appendages. in their lower forms they are among the most rudimentary of all plants, and thus of special interest physiologically, as representing the component parts of which higher plants are formed. they are subdivided into twelve groups, as follows: the first group, palmelleæ, are unicellular plants, the cells of which are either free or surrounded by a gelatinous mass, and they are propagated by the division of the endochrome. one of the most remarkable of the species of this family is protococcus cruentus, which is found at the foot of walls having a northern aspect, looking as if blood had been poured out on the ground or on stones. protococcus nivalis, again, is the cause of the red snow, of which early arctic navigators used to give such marvellous accounts. (fig. .) [illustration: fig. . a, fragment of a filament of zygnema, one of the conjugateæ; b, closterium; c, euastrium; two desmids.] the desmideaceæ, together with the plants of the next succeeding group, are favourite subjects of investigation or observation by the possessors of microscopes, an attention they merit from the beauty and variety of their forms. they are minute plants of a green colour, consisting of cells generally independent of each other, but sometimes forming brittle threads or minute fronds, and are reproduced by spores generated by the conjugation of two distinct individuals. the process of conjugation in desmids and diatoms consists in the union of the endochrome of two individuals, each of which in these families is composed of a single cell. this ultimately forms a rounded body or resting spore, which afterwards germinates, the resulting plant not however acquiring the normal form until the third generation. (fig. .) the diatomaceæ, closely allied to the preceding group in structure and reproduction, are however distinguished from them by their flinty shells, which are often beautifully sculptured. their endochrome is a golden brown, instead of green as in the desmideaceæ. the latter, also, are confined to fresh water, while the diatomaceæ are found, though not exclusively, in the sea, where their shells sometimes, microscopically minute as they are individually, form banks extending several hundred miles. it is stated that in the collection made by sir joseph hooker in the himalayas the species closely resemble our own. in the next group, confervaceæ, we are introduced to forms more like the general notion of what a plant should be. the individuals of which it consists are composed of threads, jointed, either simple or branched, mostly of a grass-green colour, and propagating either by minute zoospores or by metamorphosed joints. they are found both in fresh and salt water, and in damp situations. the number of species is very great. a considerable number consist of unbranched threads; the branched forms grow sometimes so densely as to assume the form of solid balls. after floods, when the water stands for several days, they sometimes increase to such an extent, as to form on its subsidence a uniform paper-like stratum, which while decomposing is extremely disagreeable. the name conferva has been almost discontinued as a generic title, the majority of british species being now ranged under clado- and chæto-phora. the latter are branched, and require great care and attention in order to distinguish them, on account of their general resemblance to each other. good characters are however to be found in their mode of branching and the form and comparative size of the terminal joints. the batrachospermeæ constitute a small but very beautiful group, consisting of gelatinous threads variously woven into a branched cylindrical frond. the branches are sometimes arranged, as in the british species, so that the plants appear like necklaces. in colour they pass from green, through intermediate shades of olive and purple, to black. in common with some of the higher algæ, the threads of the superficial branches send joints down the stem, changing it from simple to compound. the native species are all fluviatile. the hydrodicteæ are among the most remarkable of algæ. hydrodictyon utriculatum, the solitary british species, is found in the large pond at hampton court, and in similar situations in various parts of the country, but not very generally. it resembles a green purse or net, from four to six inches in length, with delicate and regular meshes, the reticulations being about four lines long. its method of reproduction is no less than its form. each of the cells forms within itself an enormous mass of small elliptic grains. these become attached by the extremities so as to form a network inside the cell, and, its walls being dissolved, a new plant is set free to grow to the size of the parent hydrodictyon. the nostochineæ grow in fresh water, or attached to moist soil. they consist of slender, beaded threads surrounded by a firm jelly, and often spreading into large, wavy fronds. the larger beads on the inclosed threads are reproductive spores. (fig. , a.) [illustration: fig. . a, fragment of a filament of nostoc. b, end of a filament of oscillatoria.] the oscillatoreæ are another remarkable group, on account of the peculiar animal-like motions they exhibit. they occur both in salt and fresh water, and on almost every kind of site in which there is sufficient moisture. the threads of which they are composed are jointed, and generally unbranched; they are of various tints of blue, red, and green, and, where their fructification has been ascertained, are propagated by cell division. the most curious point about them is, however, the movements of their fronds. according to dr. harvey, these are of three kinds--a pendulum-like movement from side to side, performed by one end, whilst the other remains fixed, so as to form a pivot; a movement of flexure of the filament itself, the oscillating extremity bending over from one side to the other, like the head of a worm or caterpillar seeking something on its line of march; and lastly, a simple onward movement of progression, the whole phenomenon being, dr. harvey thinks, resolvable into a spiral onward movement of the filament. whatever is the cause of this motion, it is not, as used to be supposed, of an animal nature; for the individuals of this group are undoubted plants. (fig. , b.) several species of rivularia, belonging to the oscillatoreæ, are found both in the sea and in fresh water. they are gelatinous, and have something of the appearance of nostoc, in aspect as well as in minute structure. the conjugatæ are freshwater articulated algæ, which reproduce themselves by the union of two endochromes. they are very interesting objects under the microscope, owing to the spiral or zigzag arrangement of the endochrome of many of them, and the delicacy of all. the bulbochæteæ constitute a small group, some half-a-dozen species being british. they are freshwater plants, composed of articulate branched filaments, with fertile bulbshaped branchlets. the endochrome is believed to be fertilized by bodies developed in antheridia, the contents of each fertilized cell dividing into four ovate zoospores. the last two groups of green sea-weeds consist chiefly of marine plants. of these the first, siphoneæ, is so called because the plant, however complicated, is composed invariably of a single cell. it propagates by minute zoospores, by large quiescent spores, or by large active spores clothed with cilia. it includes the remarkable genus codium, three species of which inhabit the british seas. in codium bursa the filamentous frond is spherical and hollow, presenting more the appearance of a round sponge or puff-ball than a sea-weed, and is somewhat rare. another species greatly resembles a branched sponge, and the third forms a velvety crust on the surface of rocks. another genus, vaucheria, is of a beautiful green colour, forming a velvety surface on moist soil, on mud-covered rocks overflowed by the tide, or parasitic on other sea-weeds. the most attractive plants of this family are however those of the genus bryopsis, two of which are found on the british shores. the most common one is b. plumosa, the fronds of which grow usually in the shady and sheltered sides of rock pools. the fronds of the last of the green-weed groups, the ulvaceæ, are membranous, and either flat or tubular. two of them, ulva latissima, the green, and porphyra laciniata, the purple laver, are among the most common sea-weeds, growing well up from low-water mark. the propagation in all of them is by zoospores. an allied genus, enteromorpha, is protean in its forms, which have been classed under many species. they may, however, be reduced to half a dozen. some of them are very slender, so as almost to be mistaken for confervoid plants. with the rhodospermeæ we enter a sub-order of algæ, exclusively marine, the plants in which have always held out great attractions to the collector. in structure they are expanded or filamentous, nearly always rose-coloured or purple in colour. of the fourteen groups into which they are divided by harvey, the first is ceramiaceæ, articulate algæ, constituting a large proportion of the marine plants of our shores. of the genus ceramium, c. rubrum is the most frequent, and it is found in every latitude, almost from pole to pole. it is very variable in aspect, but can always be recognized by its fruit. c. diaphanum is a very handsome species, growing often in rock pools along with the other. there are about fifteen native species altogether, some of them rare, and all very beautiful, both as displayed on paper and seen under the microscope. crouania attenuata is a beautiful plant, parasitic upon a cladostephus or corallina officinalis. it is however extremely rare, being only found in england about land's end. a more common and conspicuous, but equally handsome plant is ptilota plumosa (fig. ), which is mostly confined to our northern coasts; although p. sericea, a smaller species, or variety, is common in the south, and easily distinguished from its congener, which it otherwise greatly resembles, by its jointed branchlets and pinnules. callithamnion, halurus and griffithsia, articulate like ceramium, furnish also several handsome species. (fig. .) [illustration: fig. . species of callithamnion.] the group spyridiaceæ contains only one english plant, spyridia filamentosa, which is curiously and irregularly branched, the branches being articulate and of a pinky red. one of its kinds of fruit, consisting of crimson spores, is contained in a transparent network basket, formed by the favellæ, or short branches, whence its name. [illustration: fig. . chondrus crispus.] the cryptonemiaceæ are very numerous in genera and species. they all have inarticulate branches, some are thread-like. grateloupia filicina is a neat little plant, met with rarely on the south and west coasts. gigartina mamillosa, a common plant everywhere, is the plant sold, along with chondrus crispus, as irish or carrageen moss. a handsome little plant, stenogramme interrupta, is very rare, but it has been gathered both on the irish and english coasts. the phyllophoræ, one species of which is frequent on all our shores, may be recognised by the way in which the points and surfaces of their fronds throw out proliferous leaves. gymnogongrus has two british species, one much resembling chondrus crispus, already named, of which it was formerly considered a congener. their fructification is however very different. ahnfeltia plicata is a curiouswiry, entangled plant, almost black in colour, and like horse-hair when dry, and can scarcely be mistaken. cystoclonium purpurascens is very commonly cast up by the tide on most of our coasts. it varies in colour, but is easily distinguished by the spore-bearing tubercles imbedded in its slender branches. callophyllis laciniata is a handsome species, of a rich crimson colour, and sometimes a foot square. it can scarcely have escaped the notice of the sea-side visitor, for it is widely distributed and often thrown out in great abundance; one writer describes the shore near tynemouth as having been red for upwards of a mile with this superb sea-weed. kalymenia reniformis is another of the broad, flat algæ, but it is scarcer, and of a colour not so conspicuous. among the most frequent of our sea-weeds, both as growing in the rock pools and cast ashore, is chondrus crispus, already twice referred to in connexion with its officinal uses. it is very variable in form, one author figuring as many as thirty-six different varieties. (fig. .) chylocladia clavellosa, which is sometimes cast ashore a foot and a half long, is closely set with branches, and these again clothed with branchlets in one or two series. the whole plant is fleshy, of a rose-red or brilliant pink colour, turning to golden yellow in decay. there is another small species, confined to the extreme north of britain. halymenia ligulata is another flat red weed, but sometimes very narrow in its ramifications. furcellaria fastigiata has a round, branched, taper stem, swollen at the summit, which contains the fruit, consisting of masses of tetraspores in a pod-like receptacle. schizymenia edulis, better known perhaps by its old name iridea, is a flat, inversely egg-shaped leaf with scarcely any stem. it is one of the edible algæ, and pretty frequent in shady rock pools. gloiosiphonia capillaris is a remarkably beautiful plant, and not common, being confined to certain parts of the southern coasts. the stem is very soft and gelatinous; the spores are produced in red globular masses imbedded in the marginal filaments, which have a fine appearance under the microscope when fresh. [illustration: fig. . rhodomenia palmata.] [illustration: fig. . wormskioldia sanguinea.] the rhodomeniaceæ are purplish or blood-red sea-weeds, inarticulate, membranaceous, and cellular. among the dark-coloured is rhodomenia palmata, better known as dulse, a common and edible species. (fig. .) wormskioldia sanguinea is not only the most beautiful sea-weed, but the finest of all leaves or fronds. it is usually about six inches long, but sometimes nearly double that length and six inches broad, with a distinct midrib and branching veins, and a delicate wavy lamina, pink or deep red. the fruit is produced in winter from small leaflets growing upon the bare midrib. (fig. .) the commonest of all red sea-weeds on our coast, one of the most elegant, and much sought after by sea-weed picture makers, plocamium coccineum, belongs to this group. calliblepharis ciliata and jubata are coarser plants, the latter being the more frequent. they were formerly included in the genus rhodymenia, from which they were removed when their fruit was better understood. [illustration: fig. . ptilota plumosa.] wrangelia and naccaria are the only british genera in wrangeliaceæ. there is only one native species in each, both being rare, the latter especially. the helminthocladiæ are also a limited group, of a gelatinous structure; so much so that on being gathered they feel like a bunch of slimy worms, whence the name of the family. helminthora purpurea and divaricata with nemaleon multifidum and scinaia furcellata represent them in britain. they are nearly all very rare, pretty plants, and very effective as microscopic objects. the squamariæ, formerly included in the corallinaceæ, are a small group of inconspicuous plants resembling lichens, of a leathery texture, and growing on rocks and shells attached by their lower surface. a single genus only, polyides, represents the spongiocarpeæ. polyides rotundus resembles furcellaria fastigiata very closely, but differs widely in the fruit, which consists of spongy warts surrounding the frond, composed of spores and articulated threads. of the next group represented in britain, gelidiaceæ, we have only one plant, gelidium corneum, very common on our shores, and perhaps the most variable of all vegetable species. the sphærococcidæ include both membranaceous and cartilaginous species. of the latter is sphærococcus coronopifolius, which cannot easily be mistaken, owing to the numerous berry-like fruits that tip its branchlets. it is rather rare on the northern, but often thrown ashore in large quantities on the southern coasts. the genus delesseria has four british species, the largest being the well-known d. sinuosa, the fronds of which resemble an oak leaf in outline. the handsomest are d. ruscifolia and d. hypoglossum, which are more delicate and of a finer colour than sinuosa. there are three british species of gracillaria, in two of which the branches are cylindrical, and in the other flat. g. compressa makes an excellent preserve and pickle, but unfortunately it is the rarest of the three. nitophyllum is one of the greatest ornaments of this tribe. there are six british species, which are amongst the most delicate and beautiful of our native algæ. the corallinaceæ are remarkable for the property they possess of absorbing carbonate of lime into their tissues, so that they appear as a succession of chalky articulations or incrustations. the most common is corallina officinalis. there are two british species of corallina, and two also of the nearly allied genus, jania. of the foliaceous group there are likewise two british genera, melobesia and hildenbrantia. the next group, the laurenciaceæ, are cartilaginous and cylindrical or compressed, the frond in the greater portion of them being inarticulate and solid. they contain several species valued by collectors, although some of them are amongst our commonest plants. their colour is, when perfect, a dull purple or brownish red, but they change under the influence of light and air, while fresh water is rapidly destructive to their tints. (fig. .) [illustration: fig. . laurencia pinnatifida.] the chylocladiæ are curiously jointed plants, removed by agardh to a new genus, lomentaria, and a new order chondriæ. bonnemaisonia asparagoides is the most rare and beautiful of the tribe. the last tribe of red weeds, rhodomelaceæ, varies greatly in the structure of the frond, but the fruit is more uniform. polysiphonia and dasya contain the finest of the filiform division; the leafy one, odonthalia, a northern form, is a very beautiful sea-weed both as respects form and colour. well-grown specimens are not unlike a hawthorn twig, and of a blood red colour. the plants of the sub-order melanospermeæ, are, like the red sea-weeds, exclusively marine. they are usually large and coarse, and confined mostly to comparatively shallow water. in the laminariaceæ we find the gigantic oarweeds already briefly referred to. lessonia, which encircles in submarine forests the antarctic coasts, is an erect, tree-like plant, with a trunk from five to ten feet high, forked branches, and drooping leaves, one to three feet in length, and has been compared to a weeping willow. sir joseph hooker says, that from a boat there may on a calm day be witnessed in the antarctic regions, over these submarine groves, "as busy a scene as is presented by the coral reefs of the tropics. the leaves of the lessoniæ are crowded with sertulariæ and mollusca, or encircled with flustra; on the trunks parasitic algæ abound, together with chitons, limpets, and other shells; at the base and among the tangled roots swarm thousands of crustaceæ and radiata, while fish of several species dart among the leaves and branches." of these and other gigantic melanosperms, flung ashore by the waves, a belt of decaying vegetable matter is formed, miles in extent, some yards broad, and three feet in depth; and sir j. hooker adds that the trunks of lessonia so much resemble driftwood that no persuasion could prevent an ignorant shipmaster from employing his crew, during two bitterly cold days, in collecting this incombustible material for fuel. macrocystis and nereocystis are also giant members of this sub-order. some of the laminariæ which form a belt around our own coasts not seldom attain a length of from eight to twelve feet. the common bladder-wrack (fucus vesiculosus) sometimes grows in jutland to a height of ten feet, and in clusters several feet in diameter. the colour of most of the plants in this sub-order is some shade of olive, but several of them turn to green in drying. the first group, ectocarpeæ, is composed of thread-like jointed plants, the fructification of which consists of external spores, sometimes formed by the swelling of a branchlet. the typical genus, ectocarpus, abounds in species, a dozen or so of which, very nearly allied plants, being found around our own shores. one or two of them are very handsome. there are also some very beautiful plants in the genus sphacelaria, belonging to this group, several of them resembling miniature ferns. all the sphacelariæ are easily recognized by the withered appearance of the tips of the fruiting branches. myriotrichia is a genus of small parasitical plants, the two british species of which grow chiefly on the sea thongs (chorda). the chordariæ are sometimes gelatinous in structure, in other cases cartilaginous. the fruit is contained in the substance of the frond. the genus chordaria consists of plants which have the appearance of dark coloured twine. there are two british species, one being rather common. chorda filum, sea-rope, another string-like sea-weed, grows in tufts from a few inches to many feet in length, and tapering at the roots to about the thickness of a pig's bristle. in quiet land-locked bays with a sandy or muddy bottom, it sometimes extends to forty feet in length, forming extensive meadows, obstructing the passage of boats, and endangering the lives of swimmers entangled in its slimy cords, whence probably its other name of "dead men's lines." [illustration: fig. . padina pavonia.] the mesogloieæ in a fresh state resemble bundles of green, slimy worms. there are three british species, two of which are not uncommon. although so unattractive in external aspect, they, like many others of the same description, prove very interesting under the microscope. one of the cartilaginous species, leathsia tuberiformis, has the appearance, when growing, of a mass of distorted tubers. the species of elachista, composed of minute parasites, are, as well as unattractive like the mesogloieæ, inconspicuous, but are beautiful objects when placed under the microscope. myrionemæ are also parasitic, and even smaller than the plants of the preceding genus. in the dictyoteæ the frond is mostly flat, with a reticulated surface, which is sprinkled when in fruit with groups of naked spores or spore cysts. this tribe includes not a few of the most elegant among the algæ. in structure they are coriaceous, and include plants both with broad and narrow, branched and unbranched fronds. in haliseris there is a distinct midrib. the largest of the british dictyoteæ is cutleria multifida, sometimes found a foot and a half long; and the best known is doubtless padina pavonia, much sought after by seaside visitors where it grows. its segments are fan-shaped, variegated with lighter curved lines, and fringed with golden tinted filaments. (fig. .) owing to its power of decomposing light, its fronds, when growing under water, suggest the train of the peacock, whence its specific name. taonia atomaria somewhat resembles cutleria, but exhibits also the wavy lines of padina. the plant of this group most often cast ashore is dictyota dichotoma. it makes a handsome specimen when well dried, and is interesting on account of the manner in which it varies in the breadth of its divisions. the variety intricata is curiously curled and entangled. dictyosiphon foeniculaceus, the solitary british example of its genus, is a bushy filiform plant, remarkable for the beautiful net-like markings of its surface. the punctariæ have flattened fronds, marked with dots, which sufficiently distinguish them from all the others. a small form is often found parasitic on chorda filum, spreading out horizontally like the hairs of a bottle brush. asperococcus derives its name from its roughened surface, occasioned by the thickly scattered spots of fructification. the laminariaceæ are inarticulate, mostly flat, often strap-shaped. their spores occur in superficial patches, or covering the whole frond. the plants of this order, as we have already seen, include the giants of submarine vegetation. in point of mass they constitute the larger part of our native algæ, although they number only a few species. they are popularly known as tangle or oarweeds, and the stems of laminaria saccharina and the midrib of alaria esculenta are used as food. the sporochnaceæ are a small but beautiful tribe, inarticulate, and producing their spores in jointed filaments or knob-like masses, and remarkable for their property of turning from olive brown to a verdigris green when exposed to the atmosphere. [illustration: fig. . fucus serratus, showing a transverse section of the conceptacle, and antheridium with antherozoids escaping.] they are deep sea plants, or at least grow about low water mark. the largest of the group is desmarestia ligulata, which, with the other british species, d. aculeata, is often cast ashore. the latter species, at an early period of its existence, is clothed with tufts of slender hairs, springing from the margin of the frond. desmarestia viridis is the most delicate and also the rarest of the three. nothing like fruit has been discovered on any of them. arthocladia villosa and sporochnus pedunculatus are branched sea-weeds, covered also with tufts of closely set hairs. carpomitra cabreræ, a rare species, bears, in common with the two preceding species, its spores in a special receptacle. in the first the receptacle is pod-like; in the second knotted; and in the last mitriform. the concluding group of algæ is the fucaceæ, including the universally known sea wrack (fucus). the frond in all of them is jointless. they are reproduced by means of antheridia and oogonia developed in conceptacles, clustered together at the apex of the branches. both from their bulk and their decided sexual distinctions, they deserve to rank at the head of the order. of all sea-weeds they are also perhaps of the greatest use to man. one of the most interesting among them is the gulfweed (sargassum bacciferum), occupying a tract of the atlantic extending over many degrees of latitude. pieces of it, and of its congener, s. vulgare, are occasionally drifted to our shores, and they consequently find a place in works on british algæ, although they have no claim to be considered native plants. on rocky coasts the various species of fucus occupy the greater part of the space between tide-marks, the most plentiful being fucus vesiculosus. f. serratus (fig. ) is the handsomest of the genus, the other species being f. nodosus, said to be the most useful for making kelp, and f. canaliculatus. halidrys siliquosa is remarkable for its spore receptacles, which have quite the appearance of the seed vessel of a flowering plant. the species of cystoseira, chiefly confined to the southern coasts, are also very interesting. their submerged fronds are beautifully iridescent, and the stems, of the largest species at least, are generally covered with a great variety of parasites, animal and vegetable, the former consisting of hydrozoa and polyzoa, and other curious forms. himanthalia lorea is another remarkable plant. it has conspicuous forked fruit-bearing receptacles; but the real plants are the small cones at the base of these, and from which they are shed when ripe. as to conditions of site and geographical distribution, algæ do not differ from land plants. latitude, depth of water, and currents influence them in the same way as latitude, elevation, and station operate on the latter; and the analogy is maintained in the almost cosmopolitan range of some, and the restricted habitat of others. not many extra-european species of desmids are known, but those of diatoms are far more widely diffused, and extend beyond the limits of all other vegetation, existing wherever there is water sufficient to allow of their production; and they are found not only in water, but also on the moist surface of the ground and on other plants, in hot springs and amid polar ice. they are said to occur in such countless myriads in the south polar sea as to stain the berg and pack ice wherever these are washed by the surge. a deposit of mud, chiefly consisting of the shells of diatoms, miles long, miles broad, and of unknown thickness, was found at a depth of between and feet on the flanks of victoria land in ° south latitude. such is their abundance in some rivers and estuaries that professor ehrenberg goes the length of affirming that they have exercised an important influence in blocking up harbours and diminishing the depth of channels. the trade and other winds distribute large quantities over the earth, which may account for the universality of their specific distribution; for sir joseph hooker found the himalayan species to closely resemble our own. common british species also occur in ceylon, italy, virginia, and peru. the typical species of the confervaceæ are also distributed over the whole surface of the globe. they inhabit both fresh and salt water, and are found alike in the polar seas and in the boiling springs of iceland, in mineral waters and in chemical solutions. some of the tropical ones are exceedingly large and dense. batrachospermum vagum, in the next tribe, a native of england, is also found in new zealand. an edible species of nostochineæ, produced on the boggy slopes bordering the arctic ocean, is blown about by the winds sometimes ten miles from land, where it is found lying in small depressions in the snow upon the ice. the common nostoc of moist ground in england occurs also in kerguelen's land, high in the southern hemisphere. floating masses of monormia are often the cause of the green hue assumed by the water of ponds and lakes. certain species of oscillatoria of a deep red colour live in hot springs in india, and the red sea is supposed to have derived its name from a species of this tribe, which covers it with a scum for many miles, according to the direction of the wind. the lake of glaslough in county monaghan, ireland, owes its colour and its name to oscillatoria ærugescens, and large masses of water in scotland and switzerland are tinted green or purple by a similar agency. a few species of siphoneæ have a very wide range, two british species of codium occurring in new zealand. the ulvaceæ abound principally in the colder latitudes. enteromorpha intestinalis, a common british species, is as frequent in japan, where it is used, when dried, in soup. the rhodosperms are found in every sea, although the geographical boundaries of genera are often well-marked. gloiosiphonia, one of our rarest and most beautiful algæ, is widely diffused. of melanosperms the laminariæ affect the higher northern latitudes, sargassa abound in the warmer seas, while durvillæa, lessonia, and macrocystis characterize the marine flora of the southern ocean. the fucaceæ are most abundant towards the poles, where they attain their greatest size. the marine meadows of sargassum, conceived by some naturalists to mark the site of the lost atlantis, and which give its name to the sargasso sea, extending between ° and ° north latitude, in ° west longitude, occupy now the same position as when the early navigators, with considerable trepidation, forced through their masses on the way to the new world. sargassum is drifted into this tract of ocean by currents, the plants being all detached; and they do not produce fruit in that state, being propagated by buds, which originate new branches and leaves. (fig. .) [illustration: fig. . the gulf-weed (sargassum bacciforum).] owing to their soft, cellular structure, algæ are not likely to be preserved in a fossil state; but what have been considered such have been found as low down as the silurian formation, although their identity has been disputed, and several of them, it is more than probable, belong to other orders, and some even to the animal kingdom. freshwater forms, all of existing genera and species, are believed to have been detected in the carboniferous rocks of britain and france; others also of the green-coloured division are said to occur from the silurian to the eocene, and the florideæ to be represented from the lias to the miocene. the indestructible nature of the shells of the diatomaceæ has enabled them to survive where the less protected species may have perished. tripoli stone, a tertiary rock, is entirely composed of the remains of microscopic plants of this tribe. it is from their silicious shells that mineral acquires its use in the arts, as powder for polishing stones and metals. ehrenberg estimates that in every cubic inch of the tripoli of bilin, in bohemia, there are , , of gaillonella distans. districts recovered from the sea frequently contain myriads of diatoms, forming strata of considerable thickness; and similar deposits occur in the ancient sites of lakes in this and other countries. * * * * * before setting out in search of algæ the collector ought to provide himself with a pair of stout boots to guard his feet from the sharp-pointed rocks, as well as a staff or pole to balance himself in rock-climbing, which ought to have a hook for drawing floating weed ashore. a stout table-knife tied to the other end will be found very useful. a basket--a fishing-basket does very well--or a waterproof bag, for stowing away his plants, is also necessary. it is advisable to carry a few bottles for the very small and delicate plants, and care should be taken to keep apart, and in sea-water, any specimens of the sporochnaceæ; for they are not only apt to decay themselves but to become a cause of corruption in the other weeds with which they come in contact. these bottles should always be carried in the bag or pocket, never in the hand. sea-weeds, as every visitor to the coast knows, are torn up in great numbers by the waves, especially during storms, and afterwards left on the shore by the retiring tide. many shallow-growing species are also to be found attached to the rocks, and in the rock pools, between high and low water mark. there are three points on the beach where the greatest accumulations of floating algæ are found: high water mark, mid-tide level, and low water mark. low water occurs about five or five and a half hours after high water. the best time for the collector to commence is half an hour or so before dead low water. he can then work to the lowest point safely, and, retiring before the approaching tide, examine the higher part of the beach up to high water mark. if the coarse weeds in the rock pools and chinks are turned back, many rare and delicate algæ will be found growing under them, especially at the lowest level. the most effective method of collecting the plants of deeper water is by dredging, or going round with a boat at the extreme ebb, and taking them from the rocks and from the laminaria stems, on which a great number have their station. stems of laminaria thrown out by the waves should also be carefully examined. in all cases the weed should be well rinsed in a clear rock pool before being put away in the bag or other receptacle. the next thing to be considered is the laying out and preserving of the specimens selected for the herbarium. wherever possible these should be laid out on paper, and put under pressure as soon as gathered, or on the same day at all events. when this is impracticable, they may be spread between the folds of soft and thick towels and rolled up. thus treated the most delicate plants will keep fresh until next day. another way is to pack the plants in layers of salt, like herrings; but the most usual method of roughly preserving sea-weeds collected during an unprepared visit to the shore is by moderately drying them in an airy room out of the direct rays of the sun. they are then to be placed lightly in bags, and afterwards relaxed by immersion and prepared in the usual way. the finer plants, however, suffer more or less by this delay. if carried directly home from the sea the plants should be emptied into a vessel of sea-water. a flat dish, about fourteen inches square and three deep, is then to be filled with clean water. for most plants this may be fresh, for some it is essential that it should be salt. some of the polysiphonias and others begin to decompose at once if placed in fresh water. the griffithsias burst and let out their colouring matter, and a good many change their colour. the appliances required are some fine white paper--good printing demy, thirty-six pounds or so in weight per ream, does very well,--an ample supply of smooth blotting paper, the coarse paper used by grocers and called "sugar royal," or, best of all, bentall's botanical drying paper, pieces of well-washed book muslin, a camel's hair brush, a bodkin for assisting to spread out the plants, a pair of scissors, and a pair of forceps. the mounting paper may be cut in three sizes: in. by in., ½ in. by ¼ in., and in. by ½ in. then having selected a specimen, place it in the flat dish referred to above, and prune it if necessary. next take a piece of the mounting paper of suitable size, and slip it into the water underneath the plant, keeping hold of it with the thumb of the left hand. having arranged the plant in a natural manner on the paper, brush it gently with the camel's hair brush to remove any dirt or fragments, draw out paper and plant gently and carefully in an oblique direction, and set them on end for a short time to drain. having in this way transferred as many specimens as will cover a sheet of drying paper, lay them upon it neatly side by side, and cover them with a piece of old muslin. four sheets of drying paper are then to be placed upon this, then another layer of plants and muslin and four more sheets of drying paper, until a heap, it may be six or eight inches thick, is built up. place this between two flat boards, weighted with stones, bricks, or other weights; but the pressure should be moderate at first, otherwise the texture of the muslin may be stamped on both paper and plant. the papers must be changed in about three hours' time, and afterwards every twelve hours. in three or four days, according to the state of the weather, the muslin may be removed, the plants again transferred to dry paper, and subjected to rather severe pressure for several days. the very gelatinous plants require particular treatment. one way is to put them in drying paper and under a board but to apply no other pressure, change the drying paper at least twice during the first half hour, and after the second change of dryers apply very gentle pressure, increasing it until the specimens are fully dry. a safer and less troublesome way, for the efficacy of which we can vouch, is to lay down the plants and dry them without any pressure, afterwards damping the back of the mounting papers and placing them in the drying press. some algæ will scarcely adhere to paper. these should be pressed until tolerably dry, then be immersed in skim-milk for a quarter of an hour, and pressed and dried as before. a slight application of isinglass, dissolved in alcohol, to the under side of the specimen is sometimes necessary. before mounting, or at all events before transference to the herbarium, care should be taken to write in pencil on the back of the paper the name of the plant, if known, the place where gathered, and the date. the coarse olive weeds, such as the bladder-wrack, halidrys, and the like, may in the case of a short visit to the coast be allowed to dry in an airy place, and taken home in the rough. before pressing, in any case, they should be steeped in boiling water for about half an hour to extract the salt, then washed in clean fresh water, dried between coarse towels, and pressed and dried in the same way as flowering plants. a collection of algæ may be fastened on sheets of paper of the usual herbarium size and kept in a cabinet or portfolios, or attached to the leaves of an album. for scientific purposes, however, the latter is the least convenient way. there are few objects more beautiful than many of the sea-weeds when well preserved; but the filiform species, especially those of the first sub-order, do not retain their distinguishing characters when pressed as has been described. portions of these, however, as well as sections of stems and fruit, may be usefully dried on small squares of thin mica, for subsequent microscopic examination, or they may be mounted on the ordinary microscope slides. this is the only course possible with desmids and diatoms. the former are to be sought in shallow pools, especially in open boggy moors. the larger species commonly lie in a thin gelatinous stratum at the bottom of the pools, and by gently passing the fingers under them they will be caused to rise towards the surface, when they can be lifted with a scoop. other species form a greenish or dirty cloud on the stems and leaves of other aquatic plants, and by stripping the plant between the fingers these also may be similarly detached and secured. if they are much diffused through the water, they may be separated by straining through linen; and this is a very common way of procuring them. living diatoms are found on aquatic plants, on rocks and stones, under water or on mud, presenting themselves as coloured fringes, cushion-like tufts, or filmy strata. in colour the masses vary from a yellowish brown to almost black. they are difficult, both when living and dead, to separate from foreign matter; but repeated washings are effectual in both cases, and, for the living ones, their tendency to move towards the light may also be taken advantage of. when only the shells are wanted for mounting, the cell contents are removed by means of hydrochloric and nitric acid. the most satisfactory medium for preserving fresh desmids and diatoms is distilled water, and if the water is saturated with camphor, or has dissolved in it a grain of alum and a grain of bay salt to an ounce of water, confervoid growths will be prevented. for larger preparations of algæ, thwaites' fluid is strongly recommended. this is made by adding to one part of rectified spirit as many drops of creasote as will saturate it, and then gradually mixing with it in a pestle and mortar some prepared chalk, with sixteen parts of water; an equal quantity of water saturated with camphor is then to be added, and the mixture, after standing for a few days, to be carefully filtered. for authorities on the morphology and classification of the algæ, students may be referred to sachs' "text book" and le maout's "system of botany," of which there are good translations, and the "introduction to cryptogamic botany," by the rev. m. j. berkeley; for descriptions and the identification of species, to the text and figures of harvey's "phycologia britannica," and "nature-printed sea-weeds." both of these are however costly. among the cheaper works are "british sea-weeds," by s. o. gray (lovell, reeve & co.), "harvey's manual" and an abridgment by mrs. a. gatty, with reduced but well executed copies of the figures, of the phycologia. this synopsis can often be picked up cheap at second-hand book-stalls; and there is a very excellent low-priced work suitable for amateurs, grattann's "british marine algæ," containing recognizable figures of nearly all our native species. landsborough's "popular history of british sea-weeds," and mrs. lane clarke's "common sea-weeds," are also cheap and useful manuals on the subject. [illustration: floral design] shells. by b. b. woodward. [illustration: pond snails.] shells. introductory. in the very earliest times, long before there was any attempt at the scientific classification and arrangement of shells, they appear to have been objects of admiration, and to have been valued on account of their beauty, for we find that the pre-historic men, who, in company with the mammoth, or hairy elephant, and other animals now extinct, inhabited southern france in days long gone by, used to bore holes in them, and, like the savage of to-day, wear them as ornaments. the greek physician and philosopher, aristotle, is said to have been the first to study the formation of shells, and to raise the knowledge thus acquired into the position of a science; by him shells were divided into three orders--an arrangement preserved, with some small changes, by linnæus. it is possible that the world-wide renown of the swedish naturalist during the last century, and the ardour with which he pursued his investigations, may have given an impetus to the study of natural objects, for we find that at that period large sums were often given by collectors for choice specimens of shells. nor is this to be wondered at, for few things look nicer, or better repay trouble expended on them, than does a well-arranged and carefully mounted and named collection of shells. certainly nothing looks worse than a number of shells of all descriptions, of every kind, shape, and colour, thrown promiscuously into a box, like the unfortunate animals in a toy noah's ark, to the great detriment of their value and beauty; for, as the inevitable result of shaking against each other, the natural polish is taken off some, the delicate points and ornaments are broken off others, the whole collection becoming in time unsightly and disappointing, and all for want of a little care at the outset. in this, as in every other undertaking, "how to set about it" is the chief difficulty with beginners; and here, perhaps, a few hints gathered from experience may not be without value. one thing a young collector should always bear in mind, however, is, that no instructions can be of any avail to him unless, for his part, he is prepared to bring patience, neatness, and attention to detail, to bear upon his work. since it is important to know the best way of storing specimens already acquired, we will, in the first place, devote a few words to this point, and then proceed to describe the best means of collecting specimens, and of naming, mounting, and arranging the same. how to make a cabinet. it is a common mistake, both with old and young, to imagine that a handsome cabinet is, in the first instance, a necessity; but no greater blunder can be made: the cabinet should be considered merely an accessory, the collection itself being just as valuable, and generally more useful, when kept in a series of plain wooden or cardboard boxes. we intend, therefore, to describe the simplest possible means of keeping a collection of shells, leaving elaborate and costly methods to those who value the case more than its contents. the first thing required is some method of keeping the different species of shells apart, so that they may not get mixed, or be difficult to find when wanted. the simplest plan of doing this is to collect all the empty chip match-boxes you can find, throw away the cases in which they slide, and keep the trays, trying to get as many of a size as possible. (the ordinary bryant & may's, or bell & black's, are the most useful, and with them the trays of the small swedish match-boxes, two of which, placed side by side, occupy nearly exactly the same space as one and a half of the larger size, and so fit in with them nicely.) in these trays your shells should be placed, one kind in each tray; but although very convenient for most specimens, they will of course be too small for very many, and so the larger trays must be made. this may easily be done as follows: cut a rectangular piece of cardboard two inches longer one way than the length of the match-tray, and two inches more the other way than twice the width of the match-tray; then with a pencil rule lines one inch from the edges and parallel with them (fig. ); next cut out the little squares (_a_ _a_, _a_ _a_) these lines form in the corners of the piece of cardboard, and then with a penknife cut _half_ through the card, exactly on the remaining pencil-lines, and bend up the pieces, which will then form sides for your tray; and by binding it round with a piece of blue paper, you will have one that will look neat, uniform with the others, and yet be just twice their size. if required, you can make in the same way any size, only take care that they are all multiples of one standard size, as loss of space will thereby be avoided when you come to the next process in your cabinet. this is, to get a large box or tray in which to hold your smaller ones. [illustration: fig. . how to cut a cardboard tray.] +---+-----------+---+ |_a_| |_a_| +---+-----------+---+ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | +---+-----------+---+ |_a_| |_a_| +---+-----------+---+ the simplest plan is to get some half-dozen cardboard boxes (such as may be obtained for the asking or for a very trifling cost at any draper's), having a depth of from one to two inches (according to the size of your shells); in these your trays may be arranged in columns, and the boxes can be kept one above the other in a cupboard or in a larger box. more boxes and trays can, from time to time, be added as occasion requires, and thus the whole collection may be kept in good working order at a trifling cost. a more durable form of cheap cabinet may be made by collecting the wooden boxes so common in grocers' shops, cleaning them with sand-paper, staining and varnishing them outside, and lining them inside with paper; or, if handy at carpentering, you may make all your boxes, or even a real cabinet, for yourself. how to collect shells. provision being thus made for the comfortable accommodation of your treasures, the next consideration is, how to set about collecting them. mollusca are to be found all over the globe, from the frozen north to the sun-baked tropics, on the land or in lakes, rivers, or seas--wherever, in fact, they can find the food and other conditions suitable for their growth and development; but the collector who is not also a great traveller, must of course rely for his foreign specimens upon the generosity of friends, or else procure them from dealers. in most districts of our own country, there are, however, to be found large numbers of shells whose variety and beauty will astonish and reward the efforts of any patient seeker. begin with your own garden,--search in the out-of-the-way, and especially damp, corners; turn over the flower-pots and stones which have lain longest in one place, search amongst the roots of the grass growing under walls, and in the moss round the roots of the trees, and you will be surprised at the number of different shells you may find in a very short space of time. when the resources of the garden have been exhausted, go into the nearest lanes and again search the grass and at the roots of plants, especially the nettles which grow beside ditches and in damp places; hunt amongst the dead leaves in plantations, and literally leave no stone unturned. all the apparatus it is necessary to take on these excursions consists of a few small match or pill-boxes in which to carry home the specimens; a pair of forceps to pick up the smaller ones, or to get them out of cracks; a hooked stick to beat down and pull away the nettles; and, above all, sharp eyes trained to powers of observation. the best time to go out, is just after a warm shower, when all the grass and leaves are still wet, for the land-snails are very fond of moisture, and the shower entices them out of their lurking-places. where the ground is made of chalk or limestone, they will be found most abundant; for as the snail's shell is composed of layers of animal tissue, strengthened by depositions of calcareous earthy-matter which the creature gets from the plants on which it feeds, and these in their turn obtain from the soil--it naturally follows that the snail prefers to dwell where that article is most abundant, as an hour's hunt on any chalk-down will soon show. when garden and lanes are both exhausted, you may then turn to the ponds and streams in the neighbourhood, where you will find several new kinds. some will be crawling up the rushes near the margin of the water, others will be found in the water near the bank, while others may be obtained by pulling on shore pieces of wood and branches that may be floating in the water; but the best are sure to be beyond the reach of arm or stick, and it will be necessary to employ a net, which may be easily made by bending a piece of wire into a circle of about four inches in diameter, and sewing to it a small gauze bag; it may be mounted either on a long bamboo, or, better still, on one of those ingenious japanese walking-stick fishing-rods. for heavier work, however, such as getting fresh-water mussels and other mollusca from the bottom, you will require a net something like the accompanying figure (fig. ), about one foot in diameter. this, when attached to a long rope, may be thrown out some distance and dragged through the water-weeds to the shore, or if made with a square instead of a circular mouth, it may be so weighted that it will sink to the bottom, and be used as a dredge for catching the mussels which live half-buried in the mud. to carry the water-snails home, you will find it necessary to have tin boxes (empty mustard-tins are the best), as match-boxes come to pieces when wetted. [illustration: fig. . net for taking water-snails.] the finest collections of shells, however, are to be made at the sea-side, for the marine mollusca are both more varied in kind and more abundant than the land and fresh-water ones, and quite an extensive collection may be made in the course of an afternoon's ramble along the shore; it is necessary, however, to carefully reject such specimens as are worn by having been rolled by the waves upon the beach, as they are not of any great value in a collection; it is better, in fact, if possible, to go down to the rocks at low water and collect the living specimens. search well about and under the sea-weeds, and in the rock-pools, and, when boating, throw your dredge-net out and tow it behind, hauling it in occasionally to see what you have caught, and to empty the stones and rubbish out. at low tide also, look out for rocks with a number of round holes in them, all close together, for in these holes the pholas (fig. ) dwells, having bored a burrow in the solid rock, though _how_ he does it we do not yet quite know. the razor-shells and cockles live in the sand, their presence being indicated by a small round hole; but they bury themselves so fast that you will find it difficult to get at them. some good specimens, too, of the deeper water forms are sure to be found near the spots where fishermen drag their boats ashore, as they are often thrown away in clearing out the nets; moreover, if you can make friends with any of the said fishermen, they will be able to find and bring you many nice specimens from time to time. the reason that so much has been said about collecting living specimens, is not only because in them the shell is more likely to be perfect, but also because in its living state the shell is coated with a layer of animal matter, sometimes thin and transparent, at others thick and opaque, called the _periostracum_ (or _epidermis_), which serves to protect the shell from the weather, but which perishes with the animal, so that dead shells which have lain for some time tenantless on the ground, or at the bottom of the water, exposed to the destructive agencies that are constantly at work in nature, have almost invariably lost both their natural polish and their varied hues, and are besides only too often broken as well. since, however, even a damaged specimen is better than none at all, such should always be kept until a more perfect example can be obtained. how to prepare the shells for the cabinet. the question with which we have next to deal is, after collecting a number of living mollusks, how, in the quickest and most painless manner possible, to kill the animals in order to obtain possession of their shells. there is but one way we know of in which this may be accomplished, and that is by placing the creatures in an earthen jar and pouring _boiling_ water on them. with land, or fresh-water snails, the addition of a large spoonful of table-salt is advisable, as it acts upon them chemically, and not only puts them sooner out of pain, but also renders their subsequent extraction far easier. death by this process is instantaneous, and consequently painless; but to leave snails in cold salt water is to inflict on them the tortures of a lingering death; while for the brutality of gardeners and other thoughtless persons who seek to destroy the poor snail they find eating their plants by crushing it under foot on the gravel path, no words of condemnation are too strong, since it must always be borne in mind that snails have not, like us, _one_ nervous centre, but three, and are far more tenacious of life; hence, unless all the nerves are destroyed at once, a great deal of suffering is entailed on the poor creature; and if merely crushed under foot, the mangled portions _will live for hours_. hot water has also the advantage of tending to remove the dirt which is almost sure to have gathered on the shells, and so helping to prepare them better for the cabinet. as soon as the water is cool enough, fish out the shells one by one and proceed to extract the dead animals. this, if the mollusk is _univalve_ (_i.e._, whose shell is composed of a single piece), such as an ordinary garden snail, can easily be done by picking them out with a pin; you will find, probably, that some of the smaller ones have shrunk back so far into their shells as to be beyond the reach of a straight pin, so it will be necessary to bend the pin with a pair of pliers, or, if none are at hand, a key will answer the purpose if the pin be put into one of the notches and bent over the edge until sufficiently curved to reach up the shell. you will find it convenient to keep a set of pins bent to different curves, to which you may fit handles by cutting off the heads and sticking them into match stems. it is a good plan to soak some of the smaller snails in clean cold water before killing them, as they swell out with the water, and do not, when dead, retreat so far into their shells. if you have a microscope, and wish to keep the animals till you have time to get the tongues out, drop the bodies into small bottles of methylated spirit and water, when they will keep till required, otherwise they should of course be thrown away at once. the now empty shells should be washed in clean warm water, and, if very dirty, gently scrubbed with a soft nail or tooth brush, and then carefully dried. in such shells as the periwinkle, whelk, etc., whose inhabitants close the entrance of their dwelling with a trap-door, or _operculum_ as it is called, you should be careful to preserve each with its proper shell. if you are cleaning _bivalves_, or shells composed of two pieces, like the common mussel, you will have to remove the animal with a penknife, and while leaving the inside quite clean, be very careful not to break the ligament which serves as a hinge; then wash as before, and tie them together to prevent their gaping open when dry. sometimes the fresh-water or marine shells are so coated over with a vegetable growth that no scrubbing with water alone will remove it, and in these cases a weak solution of caustic soda may be used, but very carefully, since, if too strong a solution be employed, the surface of the shell will be removed with the dirt, and the specimen spoilt. in some shells the periostracum is very thick and coarse, and must be removed before the shell itself can be seen; but it is always well to keep at least one specimen in its rough state as an example. in other shells the periostracum is covered over with very fine, delicate hairs (_helix sericea_ and _helix hispida_, fig. ), and great care must then be taken not to brush these off. [illustration: fig. . (_a_) _helix sericea_ and (_b_) _helix hispida_.] how to mount the shells for the cabinet. when the specimens are thoroughly cleaned, the next process is to sort out the different kinds, placing each description in a different tray, and then to get them ready for mounting, for no collection will look well unless each kind is so arranged that it may be seen to the best advantage, and is also carefully named. where you have a good number, pick out first the largest specimens of their kind, then the smallest, then a series, as you have room for them, of the most perfect; and finally those which show any peculiarity of structure or marking. try, too, to get young forms as well as adult, for the young are often very different in appearance from the full-grown shell. mark on them, especially on such as you have found yourself, the locality they came from, as it is very important to the shell collector to know this, since specimens common enough in one district are often rare in another. either write the name of the place in ink on a corner of the shell itself, or gum a small label just inside it, or simply number it, and write the name of the place with a corresponding number against it in a book kept for the purpose. next select a tray large enough to hold all you have of this kind; place a piece of cotton wool at the bottom, and lay your shells upon it. for small shells, however, this method is not suitable, as the cotton wool acts on them like a spring mattress, and they are liable on the least shock to be jerked out of their trays and lost. this difficulty may be met by cutting a piece of cardboard so that it just fits into your tray, and then gumming the shells on to it in rows; but remember that, in this plan of mounting, it is impossible to take the shells up and examine them on all sides as you do the loose ones, and so you must mount a good many, and place them in many different positions, so that they may be seen from as many points of view as possible. the gum used should always have nearly one-sixth of its bulk of pure glycerine added to it; this prevents it from becoming brittle when dry, otherwise your specimens would be liable after a time to break away from the card and get lost. if the shells will not stay in the position you require, wedge them up with little pieces of cork until the gum is dry. when the shells are mounted, you must try, if you have not already done so, to get the proper names for them; it is as important to be able to call shells by their right names as it is to know people by theirs. the commoner sorts you will be able to name from the figures of them given in text-books, such as those quoted in the list at the end of this little work; but some you will find it very difficult to name, and it will then be necessary to ask friends who have collections to help you, or to take them to some museum and compare them with the named specimens there exhibited. when the right name is discovered, your label must then be written in a very small, neat hand, and gummed to the edge of the tray or on the card if your specimens are mounted. at the top you put the latin name, ruling a line underneath it, and then, if you like, add the english name; next, put the name of the place and the date at which it was found, thus:-- ===================================== helix aspersa (common snail), ----------------------------- lane near hampstead heath, july th, . ===================================== a double red ink line ruled at the top and bottom will add a finished appearance to it. how to classify the shells for the cabinet. all the foregoing processes, except the naming of your specimens, are more or less mechanical, and are only the means to the end--a properly arranged collection. for, however well a collection may be mounted, it is practically useless if the different shells composing it be not properly classified. by classification is meant the bringing together those kinds that most resemble each other, first of all into large groups having special characteristics in common, and then by subdividing these into other smaller groups, and so on. thus the animal kingdom is divided, first of all, into _sub-kingdoms_, then each _sub-kingdom_ into so many _classes_ containing those which have further characteristics in common, the _classes_ into _orders_, the _orders_ into _families_, the _families_ into _genera_, and these again into species or kinds. the mollusca, or soft-bodied animals, of whose protecting shells your collection consists, form a sub-kingdom, and are subdivided into four classes:-- . cephalopoda. . gasteropoda. . pteropoda. . lamellibranchiata (or conchifera). and these again into families, genera, and species. the space at our disposal being limited, it is impossible to do more than furnish some general outlines of the different forms. for further details it will be necessary to refer to one of the larger works, a list of which will be found on the last page. [illustration: fig. . _argonauta argo._] [illustration: fig. . "bone" of _sepia officinalis_.] class i.--the cephalopoda (head-footed) contains those mollusca that, like the common octopus, have a number of feet (or arms) set round the mouth, and is divided into those having two gills. (order i. dibranchiata); and those with four (order ii. tetrabranchiata). order i. is again divided into: (_a._) those with _eight_ feet like the argonaut (or paper-nautilus, fig. ), which fable has so long endowed with the power of sailing on the surface of the ocean, (it is even represented in one book as propelling itself through the air!) and the common octopus. (_b._) those with _ten_ feet, such as the loligo (or squid, fig. ), whose delicate internal shell so much resembles a pen in shape; the cuttle-fish (sepia, figs. & ), whose so-called "bone" (once largely used as an ink eraser) is frequently found on our southern coasts; and the pretty little _spirula_ (fig. ). [illustration: fig. . _loligo vulgaris_, and "pen."] [illustration: fig. . _sepia officinalis._] the only representative of the four-gilled order now living is the well-known pearly nautilus; but in former times the tetrabranchiata were extremely numerous, especially the _ammonites_. [illustration: fig. . _spirula_.] class ii.--gasteropoda (belly-footed) comprises those mollusca which, like the common snail, creep on the under-surface of the body, and with one exception (_chiton_, fig. ) their shells are univalve (_i.e._, composed of one piece). but before we go further, it may be well to point out the names given to different parts of a univalve shell. the aperture whence the animal issues is called the _mouth_, and its outer edge the _lip_; each turn of the shell is a _whorl_; the last and biggest, the _body-whorl_, the whorls, from the point at the top, or _apex_, down to the mouth form the _spire_; and the line where the whorls join each other is called the _suture_. the axis of the shell around which the whorls are coiled is sometimes open or hollow, and the shell is then said to be _umbilicated_ (as in fig. _b_); when closely coiled, a pillar of shell, or _columella_, is left (as in fig. ). sometimes the corner of the mouth farthest from the spire and next the columella, is produced into a channel, the _anterior canal_ (as in fig. ); whilst where the mouth meets the base of the spire there may be a kind of notch which is termed the _posterior canal_. most gasteropods are _dextral_, that is to say, the mouth is to the right of the axis as you look at it; a few, however, are _sinistral_, or wound to the left (like _physa_); whilst reversed varieties of both kinds are met with. gasteropods of the first order have comb-like gills placed in advance of the heart, and are hence termed prosobranchiata. they are divided into two groups: (_a_) _siphonostomata_ (tube-mouthed), in which the animal has a long proboscis, and a tube, or siphon, from the breathing-chamber that passes along the anterior canal of the shell, which in this group is well developed. they have a horny operculum, or lid, with which to close the aperture. (_b_) _holostomata_ (or whole-mouthed). in these the siphon is not so produced, and does not want to be protected; accordingly the mouth of the shell is _entire_, _i.e._ has no canal. the operculum is horny or shelly. the former (group _a_) includes several families: . _strombidæ_, comprising shells, like the huge _strombus_, or "fountain-shell," which is so often used to adorn the mantelpiece or rockery, and from which cameos are cut. . the _muricidæ_, of which the _murex_ (an extraordinary form of this is the "venus' comb," _murex tenuispina_, fig. ), the mitre-shells, and the red-whelks (_fusus_) are examples. [illustration: fig. . _murex tenuispina._] . the _buccinidæ_, taking its name from its type, the common whelk (_buccinum undatum_), and including such other forms as the dog-whelk (_nassa_), the _purpura_, the strange _magilus_, and the lovely harp-shells and olives (fig. ). [illustration: fig. . _oliva tessellata._] . the _cassididæ_, or "helmet-shells." _cassis rufa_, from west africa, is noted as the best species of shell for cameo engraving; with it are classed the "tun" (_dolium_) and the great "triton" (_triton tritonis_), such as the sea-gods of mythology are represented blowing into by way of trumpet, and which are used by the polynesian islanders to this day instead of horns. . the _conidæ_, whose type, the "cone-shell" (fig. ), is at once distinctive and handsome, but which in the living state is covered by a dull yellowish-brown periostracum that has to be carefully removed before the full beauties of the shell are displayed. [illustration: fig. . conus vermiculatus.] . the _volutidæ_, embracing the volutes and "boat-shells" (_cymba_). . the _cypræidæ_, or cowries (fig. ), which owe their high polish to the size of the shell-secreting organ (mantle), whose edges meet over the back of the shell, concealing it within its folds. with these is classed the "china-shell" (_ovulum_). [illustration: fig. . cypræa oniscus.] the second group, or _holostomata_, is divided into nineteen families, beginning with-- . the _naticidæ_, whose type, the genus _natica_, is well known to all shell-collectors through the common _natica monilifera_ of our coasts. . the _cancellariadæ_, in which the shells are cancellated or cross-barred by a double series of lines running, one set with the whorls, and the other across them. . the _pyramidellidæ_, which are high-spired, elongated, and slender shells, with the exception of the genus _stylina_, which lives attached to the spines of sea-urchins or buried in living star-fishes and corals. . the _solaridæ_ or "staircase-shells," whose umbilicus is so wide that, as you look down it, the projecting edges of the whorls appear like a winding staircase. it is a very short-spired shell. . the _scalaridæ_, "wentle-traps" or "ladder-shells," which may be readily recognised from their white and lustrous appearance and the strong rib-like markings of the periodic mouths that encircle the whorls. . the _cerithiadæ_, or "horn-shells," which are very high-spired, and whose columella and anterior canal are produced in the form of an impudent little tail, the effect of which, however, in the genus _aporrhais_, or "spout-shells," is taken away by the expanded and thickened lip. . in the next family, the _turritellidæ_, or "tower-shells," the type turritella is spiral; but in the allied form _vermetus_, though the spire begins in the natural manner, it goes off into a twisted tube resembling somewhat an ill-made corkscrew. the mouth in this family is often nearly round. . the _melaniadæ_, and . the _paludinidæ_, are fresh-water shells. the former are turreted, and the latter conical or globular. both are furnished with opercula, but the mouth in the first is more or less oval and frequently notched in front, while in the latter it is rounded and entire. . the _litorinidæ_, or periwinkles, need no word from us. . the _calyptræidæ_ comprise the "bonnet-limpet," or _pileopsis_, and "cup-and-saucer-limpets" (_calyptræa_). they may be described briefly as limpets with traces of a spire left. the genus _phorus_, however, is spiral, and resembles a _trochus_. they have been called "carriers" from their strange habit of building any stray fragments of shell or stone into their house, thus rendering themselves almost indistinguishable from the ground on which they crawl. . the _turbinidæ_, or "top-shells," are next in order, and of these the great _turbo marmoreus_ is a well-known example, being prepared as an ornament for the whatnot or mantelpiece by removing the external layer of the shell in order to display the brilliant pearly nacre below. these mollusca close their mouths with a horny operculum, coated on its exterior by a thick layer of porcelain-like shelly matter. with them are classed the familiar _trochus_ and other closely allied genera. . the _haliotidæ_ offer in the representative genus _haliotis_, or the "ear-shell," another familiar mantelpiece ornament. . the _ianthinidæ_, or "violet-snails," that float about in mid-atlantic upon the gulf-weed, and at certain seasons secrete a curious float or raft, to which their eggs are attached, are next in order, and are followed by-- . the _fissurellidæ_, or "key-hole" and "notched limpets," whose name sufficiently describes them. to these succeed-- . the _neritidæ_, an unmistakable group of globular shells, having next to no spire and a very glossy exterior, generally ornamented with a great variety of spots and bands. . the _patellidæ_, or true limpets, are well known to every sea-side visitor: large species, as much as two inches across, are to be found on the coast of devon, but these are pigmies compared with a south american variety which attains a foot in diameter. . the _dentaliadæ_, represented by the genus _dentalium_, or "tooth-shell," are simply slightly curved tubes, open at both ends and tapering from the mouth downwards, and cannot be mistaken. . lastly, we have the _chitonidæ_, whose single genus _chiton_ possesses shells differing from all other mollusca in being composed of eight plates overlapping each other, and in appearance reminding one of the wood-louse. this animal is not only like the limpet in form but also in habits, being found adhering to the rocks and stones at low-water. order ii.--pulmonifera. contains the air-breathing _gasteropods_, and to it consequently belong all the terrestrial mollusca, though some few aquatic genera are also included. the members of this order have an air-chamber instead of gills, and are divided into two groups, (_a_) those without an operculum, and (_b_) those having an operculum. foremost in the first group stands the great family-- . _helicidæ_, named after its chief representative, the genus _helix_. it also includes the "glass-shell" (_vitrina_), the "amber-shell" (_succinea_), and such genera as _bulimus_, _achatina_, _pupa_, _clausilia_ (fig. ), etc., which differ from the typical _helix_ in appearance, possessing as they do comparatively high spires. [illustration: fig. . _clausilia biplicata._] . the _limacidæ_, or "slugs," follow next; of these only one, the genus _testacella_, has an external shell stuck on the end of its tail; the rest have either a more or less imperfect shell concealed underneath the mantle, or else none at all. . the _oncidiadæ_ are slug-like, and devoid of shell. . the _limnæidæ_ embrace the "pond-snails," chief of whom is the well-known, high-spired _limnæa stagnalis_. other shells of this family associated with _limnæa_ are, however, very different in shape; for instance, _physa_ has its whorls turning to the left instead of to the right; _ancylus_ (fig. ), or the freshwater limpet, is of course limpet-like; while _planorbis_, or the "coil-shell," is wound like a watch-spring. . the _auriculidæ_ includes both spiral shells, such as _auricula_ and _charychium_, and a limpet-like one _siphonaria_. at the head of group _b_ stands , _cyclostomidæ_. _cyclostoma elegans_ is a common shell on our chalk-downs, and well illustrates its family, in which the mouth is nearly circular. foreign examples of this genus are much esteemed by collectors. the other two families are, ( ) _helicinidæ_ and ( ) _aciculidæ_. order iii.--opisthobranchiata. these animals carry their gills exposed on the back and sides, towards the rear of the body. only a few have any shell. . the _tornatellidæ_, which have a stout little spiral shell. . the _bullidæ_, in which the spire is concealed (fig. ). . the _aplysiadæ_, where the shell is flat and oblong or triangular in shape. the remaining families are slug-like and shell-less. [illustration: fig. . _bulla ampulla._] order iv.--nucleobranchiata. derives its name from the fact that the animals constituting it have their respiratory and digestive organs in a sort of nucleus on the posterior part of the back, and covered by a minute shell. as they are pelagic, the shells are not readily to be obtained. they are divided into two families, _firolidæ_ and _atlantidæ_. class iii.--pteropoda. like the last, these pretty little mollusca are ocean-swimmers. the members of one division of them, to which the _cleodora_ belongs, is furnished with iridescent external shells. [illustration: fig. . _petunculus guerangeri._] [illustration: fig. . _venus plicata._] class iv.--the lamellibranchiata (plate-gilled), or conchifera (shell-bearing), includes the mollusca commonly known as "bivalves," the animal being snugly hidden between two more or less closely fitting shelly valves. the oysters, cockles, etc., are examples of this class. the two valves are fastened together near their points, or beaks (technically called _umbones_), by a tough elastic ligament, sometimes supplemented by an internal cartilage. if this be severed and the valves parted, it will be found that in most cases they are further articulated by projecting ridges or points called the _teeth_, which, when the valves are together, interlock and form a hinge; the margin of the shell on which the teeth and ligament are situated is termed the _hinge-line_. a bivalve is said to be _equivalve_ when the two shells composing it are of the same size, _inequivalve_ when they are not. if the umbones are in the middle, the shell is _equilateral_ (fig. ); but _inequilateral_ when they are nearer one side than the other (fig. ). if the shell be an oyster or a scallop, you will find on the inside a single circular scar-like mark near the centre; this is the point to which the muscles that close the valves and hold them so tightly together are attached. in the majority of bivalves, however, there are two such muscular impressions, or scars, one on either side of each valve of the shell. the former group on this account are often called _monomyaria_ (having one shell-muscle), and the latter _dimyaria_ (having two shell-muscles). in the last named the two muscular impressions are united by a fine groove (or _pallial-line_), which in some runs parallel to the margin of the shell (fig. ), whilst in others it makes a bend in (_pallial-sinus_) on one side of the valve towards the centre (fig. ). in monomyaria it will be found running parallel to the margin of the shell. it marks the line of attachment of the mantle or shell-secreting organ of the animal to the shell which grows by the addition of fresh matter along its edges, so that the concentric curved markings so often seen on the exterior correspond in their origin with the periodic mouths of the gasteropods. the bivalves are all aquatic, and many bury themselves in the sand or mud by means of a fleshy, muscular foot. these are furnished with two siphons, or fleshy tubes, sometimes united, sometimes separate, through which they respire, drawing the water in through one and expelling it by the other. those kinds whose habit it is to bury themselves below the surface of the mud or sand are furnished with long retractile siphons, and to admit of their withdrawal into the shell, the mantle is at this point attached farther back, giving rise to the _pallial-sinus_ above described; this sinus is deeper as the siphons are proportionately longer, and in many cases, too, the valves do not meet at this point when the shell is closed. attention to these particulars is necessary when arranging your bivalves, as on them their classification depends, the class being divided into-- _a._ asiphonida (siphonless). _b._ siphonida _integro-pallialia_ (with siphons).--pallial-line entire. _c._ siphonida _sinu-pallialia_ (with siphons).--sinus in pallial-line. division _a_.--asiphonida--is next subdivided into-- . the _ostreidæ_, or oysters, which are deservedly a distinct family in themselves. . the _anomiadæ_, comprising the multiform and curiously constructed _anomia_, with the "window-shells" (_placuna_). . the _pectinidæ_, taking its name from the genus _pecten_, or "scallop-shells," of which one kind (_p. maximus_) is frequently to be seen at the fishmongers' shops. the "thorney oysters" (_spondylus_) take rank here, and are highly esteemed by collectors, one specimen indeed having been valued at £ ! . the _aviculidæ_, or "wing-shells," among which are numbered the "pearl-oyster" of commerce (_meleagrina margaritifera_). the strange t-shaped "hammer oyster" belongs to this family, as does also the _pinna_. the pinnas, like the mussels and some other bivalves, moor themselves to rocks by means of a number of threads spun by the foot of the mollusc, and termed the _byssus_, which in this genus is finer, more silky, than in any other, and has been woven into articles of dress. . the _mytilidæ_, or mussels, including the _lithodomus_, or "date-shell," which bores into corals and even hard limestone rocks. [illustration: fig. . hinge-teeth of _arca barbata_.] . the _arcadæ_, or "noah's-ark-shells," characterized by their long straight hinge-line set with numerous very fine teeth (fig. ). the "nut-shell" (_nucula_) belongs to this family. . the _trigoniadæ_, whose single living genus, the handsome _trigonia_ (fig. ), is confined to the australian coast-line, whereas in times now long past they had a world-wide distribution. [illustration: fig. . _trigonia margaritacea._] . the _unionidæ_, comprising the fresh-water mussels. division _b_.--siphonida _integropallialia_. . the _chamidæ_, represented by the reef-dwelling _chama_. . the _tridacnidæ_, whose sole genus _tridacna_ contains the largest specimen of the whole class of bivalves, the shells sometimes measuring two feet and more across. . the _cardiadæ_, or cockles. . the _lucinidæ_, in which the valves are nearly circular, and as a rule not very attractive in appearance, though the "basket-shell" (_corbis_) has an elegantly sculptured exterior. . the _cycladidæ_, whose typical genus _cyclas_, with its round form and thin horny shell, is to be found in most of our ponds and streams. . the _astartidæ_, a family of shells having very strongly developed teeth, and the surface of whose valves is often concentrically ribbed. [illustration: fig. . hinge of _cardita sinuata_.] . the _cyprinidæ_, which have very solid oval or elongated shells and conspicuous teeth (fig. ). the "heart-cockle" (_isocardia_) belongs to this family. division _c_.--siphonida _sinu-pallialia_. . the _veneridæ_. the hard, solid shells of this family are for elegance of form and beauty of colour amongst the most attractive a collector can posses. their shells are more or less oval and have three teeth in each valve (fig. ). [illustration: fig. . hinge of _cytherea crycina_.] [illustration: fig. . hinge of _lutraria elliptica_] . the _mactridæ_ are somewhat triangular in shape, and may be at once recognised by the pit for the hinge-ligament, which also assumes that form, as seen in the accompanying figure of _lutraria elliptica_ (fig. ). . the _tellinidæ_ comprise some of the most delicately tinted, both externally and internally, of all shells. in some, coloured bands radiate from the umbones, and well bear out the fanciful name of "sunset shells" bestowed upon them. their valves are generally much compressed. . the _solenidæ_, or "razor-shells," rank next, and are readily recognised by the extreme length of the valves in proportion to their width, and also by their gaping at both ends. . the _myacidæ_ or "gapers," have the siphonal ends wide apart (in the genus _mya_ both ends gape), and are further characterized by the triangular process for the cartilage, which projects into the interior of the shell. one valve (the left) is generally smaller than the other. . the _anatinidæ_ have thin, often inequivalve pearly shells. the genus _pandora_ is the form most frequently met with in collections. . the _gastrochænidæ_ embraces two genera (_gastrochæna_ and _saxicava_) of boring mollusca, which perforate shells and rocks, and also, the remarkable tube-like "watering-pot-shell" (_aspergillum_) which is hardly recognisable as a bivalve at all. [illustration: fig. . _pholas dactylus._] . the _pholadidæ_ concludes the list of bivalves, and comprises the common rock-boring pholas (fig. ) of our coasts and the wood-boring shipworm "teredo" (fig. ). * * * * * although the _brachiopoda_, or "lamp-shells," are not true mollusca, they are not very far removed from them, and are so often to be found in cabinets that it will not do to pass them over, especially since in past times they were very abundant, an enormous number occurring in the fossil state. only eight genera are now living. shells belonging to this class are readily recognised by the fact of one valve being larger than the other, and possessing a distinct peak, the apex of which is perforated. the _terebratulidæ_ are the most extensive family of this class. [illustration: fig. . _teredo navalis._] how to arrange the shells in the cabinet. when you have arranged your specimens in the order above indicated, proceed to place them in your boxes, arranging and labelling them after the manner shown in the accompanying diagram. +----------+----------+----------+----------+----------+ | class. | | | | | +----------+ species. | species. | species. | species. | | order. | | | | | +----------+----------+----------+----------+----------+ | family | | | | | | name. | | | | | +----------+ species. | species. | species. | species. | | generic | | | | | | name. | | +----------+ | +----------+----------+----------+ family +----------+ | | | | name. | | | species. | species. | species. +----------+ species. | | | | | generic | | +----------+----------+----------+ name. +----------+ | | | +----------+ | | | generic | | | | | species. | name. | species. | species. | species. | | | | | | | +----------+----------+----------+----------+----------+ | | | | | generic | | species. | species. | species. | species. | name. | | | | | | | +----------+----------+----------+----------+----------+ | | | generic | | | | species. | species. | name. | species. | species. | | | | | | | +----------+----------+----------+----------+----------+ | | | | | | | species. | species. | species. | species. | species. | | | | | | | +----------+----------+----------+----------+----------+ on the lid, or on a slip of paper or card placed at the head of your columns of trays, write the class and order, with its proper number (i., ii., etc., as the case may be); then at the top of your left-hand column place the family and its number, and under it the name of the first genus. the species (one in each tray) come next, then the name of the next genus following it, succeeded by its species, and so on. the object of the young collector should be to obtain examples of as many _genera_ as possible, since a collection in which a great number of genera are represented is far more useful and instructive than one composed of a great many species referable to but few genera. he will also find it very convenient to separate the british shells from his general collection, sub-dividing them for convenience into "land and fresh-water," and "marine." of these he should endeavour to get every species, and even variety, making the thing as complete as possible. or a separate collection may be made of all those kinds which he can find within a certain distance of his own home. a collection of this sort possesses, in addition to its scientific worth, an interest of its own, owing to the local associations that invariably connect themselves with it. table of some of the more important genera, showing the approximate number of species belonging to each genus and their distribution. class i.--cephalopoda. order i.--dibranchiata. section a.--_octopoda._ family. genus. no. of species. distribution. . argonauta tropical seas. . octopus rocky coasts in temperate and tropical regions. section b.--_decapoda_. . loligo cosmopolitan. . sepia on all coasts. . spirula all the warmer seas. order ii.--_tetrabranchiata_. . nautilus or chinese seas, indian ocean, persian gulf. class ii.--gasteropoda. order i.--prosobranchiata. division _a_.--_siphonostomata._ no. of family. genus. species. distribution. . strombus w. indies, mediterranean, red sea, indian ocean, pacific--low water to fathoms. pteroceras india, china. . murex on all coasts. columbella sub-tropical regions, in shallow water on stones. mitra tropical regions, from low water to fathoms. fusus on all coasts. . buccinum northern seas, from low water to fathoms. eburna red sea, india, australia, china, cape of good hope. nassa world-wide--low water to fathoms. purpura world-wide--low water to fathoms. harpa tropical--deep water, sand, muddy bottoms. oliva sub-tropical--low water to fathoms. . cassis tropical regions, in shallow water. dolium mediterranean, india, china, w. indies, brazil, new guinea, pacific. triton temperate and sub-tropical regions, from low water to fathoms. ranella tropical regions, on rocks and coral-reefs. pyrula sub-tropical regions, in to fathoms. . conus equatorial seas--shallow water to fathoms. pleurotoma almost world-wide--low water to fathoms. . voluta on tropical coasts, from the shore to fathoms. cymba west coast of africa, lisbon, straits of gibraltar. marginella mostly tropical. . cypræa warmer seas of the globe, on rocks and coral-reefs. ovulum britain, mediterranean, w. indies, china, w. america. division _b_.--_holostomata._ . natica arctic to tropical regions, on sandy and gravelly bottoms, from low water to feet. sigaretus e. and w. indies, china, peru. . cancellaria w. indies, china, s. america, e. archipelago--low water to fathoms. . pyramidella w. indies, mauritius, australia, in sandy bays and on shallow mud-banks. odostomia britain, mediterranean, and madeira--low water to fathoms. chemnitzia world-wide--low water to fathoms. eulima cuba, norway, britain, india, mediterranean, australia-- to fathoms. . solarium sub-tropical and tropical--widely distributed. . scalaria world-wide--low water to fathoms. . cerithium world-wide. potamides africa and india, in mud of large rivers. aporrhais labrador, norway, britain, mediterranean-- to fathoms. . turritella world-wide--low water to fathoms. vermetus portugal, mediterranean, africa, india. . melania s. europe, india, philippines and pacific islands--in rivers. melanopsis spain, australia, asia minor, new zealand--in rivers. . paludina northern hemispheres, africa, india, china, etc.--in lakes and rivers. ampullaria s. america, w. indies, africa, india--in lakes and rivers. . litorina on all shores. rissoa world-wide--in shallow water on sea-weed to fathoms. . calyptrea world-wide--adherent to rocks, etc. crepidula west indies, mediterranean, cape of good hope, australia. pileopsis britain, norway, mediterranean, e. and w. indies, australia. hipponyx w. indies, galapagos, philippines, australia. phorus w. indies, india, javan and chinese seas--in deep water. . turbo on the shores of tropical seas. phasinella australia, pacific, w. indies, mediterranean. imperator s. africa, india, etc. trochus world-wide--from low water to fathoms. rotella india, philippines, china, new zealand. stomatella cape, india, australia, etc. . haliotis britain, canaries, india, australia, california--on rocks at low water. stomatia java, philippines, pacific, etc.-- under stones at low water. . ianthina gregarious in the open seas of the atlantic and pacific. . fissurella world-wide--on rocks from low water to fathoms. emarginula britain, norway, philippines, australia--from low water to fathoms. . nerita on the shores of all warm seas. neritina in fresh waters of all warm countries, and in britain. navicella india, mauritius, moluccas, australia, pacific--in fresh water, attached to stones. . patella on all coasts--adhering to stones and rocks. . dentalium world-wide--buried in mud. . chiton world-wide--low water to fathoms. order ii.--pulmonifera. division _a_.--_inoperculata._ no. of family. genus. species. distribution. . helix , } succinea } world-wide--on land in moist places. bulimus } achatina world-wide--burrowing at roots and bulbs. pupa world-wide--amongst wet moss. clausilia europe and asia--in moist spots. . limax europe and canaries--on land in damp localities. testacella s. europe, canaries, and britain-- burrowing in gardens. . oncidium britain, red sea, mediterranean--on rocks on the seashore. . limnæa europe, madeira, india, china, n. america--in ponds, rivers, lakes, etc. physa america, europe, s. africa, india, philippines--in ponds, rivers, lakes, etc. ancylus europe, n. and s. america--in ponds, rivers, lakes, etc. planorbis europe, n. america, india, china--in ponds, rivers, lakes, etc. . auricula tropical--in salt marshes. siphonaria world-wide--between high and low water. division _b_.--_operculata._ . cyclostoma s. europe, africa } cyclophorus india, philippines }--on land. pupina philippines, new guinea } . helicina w. indies, philippines, central america, islands in pacific--on land. . acicula britain, europe, vanicoro--on leaves and at roots of grass. geomelania jamaica--on land. order iii.--opisthobranchiata. division _a_.--_tectibranchiata._ no. of family. genus. species. distribution. . tornatella red sea, philippines, japan--in deep water. . bulla widely distributed--low water to fathoms. . aplysia britain, norway, w. indies--low water to fathoms on sea-weed. . pleurobranchus britain, norway, mediterranean. division _b_.--_nudibranchiata._ - . all shell-less. order iv.--nucleobranchiata. no. of family. genus. species. distribution. . firola atlantic, mediterranean. carinaria atlantic and indian oceans. . atlanta warmer parts of the atlantic. class iii.--pteropoda. division _a_.--_thecosomata._ no. of family. genus. species. distribution. . hyalea } cleodora } atlantic, mediterranean, indian ocean. . limacina arctic and antarctic seas. division _b_.--_gymnosomata._ . clio, etc. shell-less. class iv.--lamellibranchiata. no. of family. genus. species. distribution. division _a_.--_asiphonida._ . ostrea world-wide--in estuaries, attached. . anomia india, australia, china, ceylon-- attached to shells from low water to fathoms. placuna scinde, north australia, china--in brackish water. . pecten world-wide--from to fathoms. lima norway, britain, india, australia-- from to fathoms. spondylus tropical seas--attached to coral-reefs. . avicula britain, mediterranean, india-- fathoms. perna in tropical seas--attached. pinna united states, britain, mediterranean, australia, pacific--low water to fathoms. . mytilus world-wide--between high and low water mark. modiola british and tropical seas--low water to fathoms. . arca in warm seas--from low water to fathoms. pectunculus west indies, britain, new zealand-- from to fathoms. nucula norway, japan--from to fathoms. . trigonia off the coast of australia. . unio world-wide--in fresh waters. anodon north america, europe, siberia--in fresh waters. division _b_.--_siphonida._ . chama in tropical seas on coral reefs. . tridacna indian and pacific oceans, chinese seas. . cardium world-wide--from the shore line to fathoms. . lucina tropical and temperate seas--sandy and muddy bottoms--from low water to fathoms. kellia norway, new zealand, california--low water to fathoms. . cyclas temperate regions--in all fresh waters. cyrena from the nile and other rivers to china--and in mangrove swamps. . astarte mostly arctic--from to fathoms. crassatella australia, philippines, africa, etc. . cyprina from britain to the most northerly point yet reached--from to fathoms. circe britain, australia, india, red sea-- to fathoms. isocardia mediterranean, china, japan--burrowing in sand. cardita tropical seas--from shallow water to fathoms. . venus } world-wide--buried in sand, from low cytherea } water to fathoms. artemis northern to tropical seas--from low water to fathoms. tapes widely distributed--burrowing in sand, from low water to fathoms. venerupis britain, canaries, india, peru--in crevices of rocks. . mactra world-wide--burrowing in sand. lutraria widely distributed--burrowing in sand. . tellina in all seas--from the shore line to fathoms. psammobia britain, pacific and indian oceans-- from the littoral zone to fathoms. sanguinolaria w. indies, australia, peru. semele brazil, india, china, etc. donax norway, baltic, britain--in sand near low water mark. . solen world-wide--burrowing in sand. solecurtus britain, africa, madeira, mediterranean--burrowing in sand. . mya north seas, w. africa, philippines, etc.--river mouths from low water to fathoms. corbula united states, britain, norway, mediterranean, w. africa, china-- from to fathoms. . anatina india, w. africa, philippines, new zealand. thracia greenland to canaries and china--from to fathoms. pandora spitzbergen, panama, india--from to fathoms, burrowing in sand and mud. . gastrochæna w. indies, britain, red sea, pacific islands--from shore line to fathoms. saxicava arctic seas, britain, mediterranean, canaries and the cape--in crevices and boring into limestone and rocks. aspergillum red sea, java, new zealand--in sand. . pholas almost universal--from low water to fathoms. xylophaga norway, britain, s. america--boring into floating wood. teredo in tropical seas--from low water to fathoms. some works of reference. mollusca in general. "a manual of mollusca." by dr. s. p. woodward. "tabular view of the orders and families of the mollusca." published by the society for promoting christian knowledge. "cassell's natural history," latest edition, article on the mollusca. by dr. henry woodward. british mollusca. "a history of british mollusca and their shells." by professor e. forbes and s. hanley. "british conchology." by j. g. jeffreys. "common shells of the sea-shore." by rev. j. g. wood. british land and fresh-water mollusca. "land and fresh-water mollusca indigenous to the british isles." by lovell reeve. "a plain and easy account of the land and fresh-water mollusca of great britain." by ralph tate. [illustration] fossils. by b. b. woodward. fossils. introductory. geology is of all "hobbies" the one best calculated not only to develop the physical powers, but also, if pursued with any degree of earnestness, to train and extend the mental faculties. to study geology properly, the rocks themselves must be visited and carefully observed, their appearance noted, and the fossils, if any, which they contain, collected. this necessitates many a pleasant walk into the open country to quarries and cuttings, or rambles along the sea-shore to cliffs which may be worth investigating, whilst botany, entomology, or any other congenial pursuit, may be followed on the way; for natural science in its different branches has so many points of connection that it is impossible to study one of them without increasing one's interest in, and knowledge of, all the others. again, in arranging, classifying, and studying at home the specimens collected on these expeditions, many an hour may be usefully spent; habits of exactitude and neatness are acquired; whilst in endeavouring to draw correct conclusions as to the way in which particular rocks were formed, and by what agencies brought to their present position, the reasoning faculties are exercised and developed. the existence of fossil shells and bones in various strata of the earth's crust attracted attention at a very early date of the world's history; the egyptian priests were aware of the existence of marine shells in the hills bounding the nile valley, and from this fact herodotus drew the conclusion that the sea formerly covered the spot. the bones of the larger mammalia (rhinoceros, elephant, etc.), were, however, thought by the ancients to be human, and hence arose the idea of a race of giants having existed at some previous period of the earth's history. it was not, however, until near the end of the last century that geology began to be recognised as a science, and the true bearing of fossils in relation to the rocks in which they were found was conclusively proved. william smith in england, and werner in germany, while working independently of each other, both came to the same conclusion, viz. that the numerous strata invariably rested on each other in a certain order, and that this order was never inverted,[ ] whilst william smith in addition proved that each group of rocks, and even each stratum, had its own peculiar set of fossils, by which it might be recognised wherever it occurred. from that time forth the study of the various fossils began to be considered as a separate science apart from that of the beds containing them; this is now known as palæontology, the study of the composition of the rocks themselves being termed petrology. [ ] except in such cases where the rocks themselves have been displaced by movements of the earth's crust. at this moment, however, we are less concerned with the study of rocks and fossils than with the best and simplest way of collecting, preparing, and arranging specimens as a means to this study. the cabinet. with regard to the cabinet for such specimens as you are able to collect, the same advice holds good as that given in a previous manual (the young collector's shell book), namely, the simpler the cabinet the better, though of course card-board boxes would not as a rule be strong enough to stand the weight of the specimens, and hence it is advisable to have wooden ones. the boxes in which oakey's wellington knife-powder is sent out (they measure about in. × in. × in.) are on the whole the most convenient size, and are easily obtainable at any oil and colourman's. these, when painted over with berlin black, after first removing the external labels, look very neat. the inside may be papered according to taste, when the trays may be arranged in order ready for the reception of your specimens.[ ] [ ] for description of trays, see "the young collector's shell-book." implements required when collecting. a certain amount of apparatus is needful in collecting geological specimens. it is necessary to break open the hard rocks in order to get at the fossils within, and for this purpose a strong hammer is required. one end of the hammer-head should be square, tapering, slightly, to a flat striking face; for when thus shaped the edges and corners are less likely to break off; the other side should be produced into a rather long, flat, and slightly curved pick, terminating in a chisel-edge at right-angles to the handle; the total length of the head should not exceed ½ in., the striking face being in. from the centre of the eye in which the handle ( in. long) is inserted; the latter should be made of the toughest ash, american hickory, or "green-heart," and fixed in with an iron wedge ("roughed" to prevent its coming out again), taking care that ¼ in. of the handle protrudes on the other side. it is the usual practice, but a mistaken one, to cut it off level with the hammer head, which is likely, under these circumstances, to come off after it has been in use for a time, whereas, by leaving a small portion of the wedged-out end projecting, this mischance is avoided, and your weapon will not fail even when used to drag its owner up a stiff ascent. it is better to shape and fix the handle yourself, as by this means you can not only cut it to fit your hand, but may rely upon its being properly fastened in. by filing grooves around it an inch apart, it will serve to take rough measurements with, while a firm grasp may be insured by bees-waxing instead of polishing it. another and much smaller hammer will also be necessary, chiefly for home use, to trim the specimens before putting them away in the cabinet; the head of this hammer must not be more than ½ inches long, the handle springing from the centre; one end has a flat striking face, square in section, the other, instead of being formed like a pick, is wedge-shaped, the sharp edge being at right-angles to the handle. next to a hammer, a cold chisel is indispensable to the collector, since without its aid many a choice specimen embedded in the middle of a mass of rock too large to break with the hammer would have to be left behind. there is one thing, however, to beware of in using this tool--it has sometimes to be hit with great force, and should you chance to miss it and strike your hand instead, the result may be more serious than even a severe bruise. to prevent this, procure from the shoemaker or saddler a piece of thick leather, about inches in diameter, having a hole cut in the centre through which to pass the shank of the chisel, and, thus protected, you may wield the hammer with impunity. for digging fossils out of clay, an old, stout knife, such as the worn-down stump of a carver, is handy, and in sandy beds an ordinary garden trowel is very useful, whilst in a chalk-pit a small saw is sometimes of great aid in extricating a desirable specimen. the same may be said of an ordinary carpenter's wood-chisel. for picking up small and delicate specimens, a pair of forceps should be carried, whilst without a pocket lens no true naturalist ever stirs abroad. an ordinary stout canvas satchel, such as is commonly used by schoolboys, is the best thing for carrying home your specimens; this may be made much stronger by the addition of two short strips of leather stitched on the back and running, one from each ring, to which the strap passing over the shoulder is fastened, down to the bottom of the bag; by leaving a small portion unstitched near the bottom of each of these, wide enough for the shoulder-strap to pass through, the satchel may at a moment's notice be slung knapsackwise on the shoulders--a method of carrying it which is, as all who have tried it know, by far the most convenient when it is heavily laden or not in immediate requisition. a stout leather belt may be worn in which to carry all your hammers, supporting it on the side where the heavy hammer hangs by a band passing over the opposite shoulder. before starting on an excursion, make a practice of seeing that you have everything with you, or when the critical moment comes, and some choice and fragile specimen is ready to be borne off, you may find that you are without the means necessary for taking it home. for ordinary hard specimens, newspaper well crumpled around them is without its equal, but some of the more delicate must be first wrapped in tissue paper or even cotton-wool, whilst the most fragile fossils should be packed in tins with bran or sawdust, the particles of which fill in all the corners and press equally everywhere, a useful faculty which cotton wool does not possess. when neither of these are to be obtained, dry sand will answer quite as well, though it is heavier to carry. although not absolutely necessary in the field, it is often useful to have a small bottle of acid in your pocket (nitric acid diluted to - th with distilled water is the best) with which to test for limestones; a drop of acid placed on a rock will, if there be any carbonate of lime in it, immediately begin to fizz. finally, every young collector should carry a note-book, and carefully record in it what he sees in each pit he visits, while, if it can be procured or borrowed, a geological map of the district you are exploring is a great help, for with its aid and that of a good compass you become practically independent of much extraneous assistance. how to use your implements. we will suppose by way of illustration that near us flows a river, on the rising ground above which is a pit that we propose to visit for the purpose of putting our apparatus into practical operation. when we have reached the floor of the pit, and stand looking up at the section before us, we are at first rather puzzled as to what the beds, which we see before us, are; for as the pit has not been worked for some time, its sides are partially overgrown with grass, and in places bits and pieces of the upper beds have fallen down and form a heap beneath which the lower ones lie buried. we must therefore make our way to those spots where the beds are left clear, and find out, if possible, what they are. by climbing up one of the heaps of fallen earth (_talus_) we reach the top, where, first of all, under the roots of the grass and shrubs, we find the mould in which these grow, and which is formed of the broken up (_disintegrated_) rocks forming the still higher ground above, and which the rains, frosts and snows, aided afterwards by the earthworms, have converted into mould. this, geologically speaking, is called _surface soil_, and is here about two feet deep. just below it we find a layer of coarse gravel; the pebbles of which this is composed are of all sorts, sizes, and shapes, and are stained a deep brown by oxide of iron. most of them are flints, and by diligent search you may find casts and impressions in these of sponges, shells, spines of sea urchins, etc. flints, whether from gravel or their parent rock the chalk, are easiest broken by a light smart tap of the hammer, though when it is desired to shape them for the cabinet a soft iron hammer should be used, and the piece to be shaped placed on a soft pad on the knee, for when struck with a steel hammer flints splinter in all directions, and often through the very portion you most desire to preserve. in one spot we find a mass of sand included in the gravel; this mass is thickest in the middle, and tapers away towards each end, its total length being about fifty feet. could we see the whole mass, we should probably find it to be a patch lying on the gravel and thinning out all around its edges; in other words it would be shaped like a lens--"_lenticular_" as geologists term it. when we examine this mass more closely, we find that the layers of sand do not run parallel with the bed, but are inclined in different directions, sometimes lying one way, sometimes another. this _false bedding_ is due to the sand having been thrown down in waters agitated by strong currents that swept over the spot, now in one direction and now in another, scattering at one moment half the sand they had just piled up one way only to redeposit it the next minute in another. in the gravel also may be observed a similar though less marked arrangement, owing to the larger size of its constituents, which of course required a still stronger current action to wash them down. amongst the sand we now see some shells, and set to work to dig them out very carefully, for they are exceedingly brittle. the best specimens are to be obtained by throwing down masses of the sandy material and searching in it; but only the stronger and finer examples will bear such usage. we next notice that these shells are precisely similar to those still found with living occupants in the river below, only they are no longer of a brownish colour, but owing to the loss of the animal matter of the shell have an earthy, dirty-white appearance. to carry these home they should be packed in bran in one of your tins with a note as follows made on a piece of paper and placed just inside--"sand in gravel: topmost bed ---- pit, august nd, -." then if you are not able to work them out at once on reaching home, you will not forget whence they came. from the appearance of these sands and gravels, and the presence in them of shells exactly like those in the river below, it may reasonably be inferred that they once formed a portion of the bed of that river long ago, before it had scooped out its valley to the present depth. there is, however, something else in this sand-bed--a piece of bone protruding; clear away the sand above it, and dig back until the whole is visible. it is broken through in one or two places, but otherwise is in fair condition; remove the pieces carefully one by one, and wrap them in separate pieces of paper, and then proceed to search for others. these bones, which are plentiful in some of our river valley gravel-beds, are the remains of animals that once roamed in the forests which at that time covered the country; they were probably either drowned in crossing the water, or got stuck in the mud on the banks on coming down to drink. a fine collection was made at ilford by the late sir antonio brady, and is now in the british museum (natural history) at south kensington. besides the bones of animals, you may expect to find examples of all, or nearly all, the different rocks in which the river has cut its valley, and samples of these may be picked out and taken home. each specimen should be wrapped in a separate piece of paper to prevent its rubbing against others, care being taken to note the locality either by writing it on the paper or by affixing to the specimen a number corresponding to one in your note book against the description you have written of the bed. the gravel, with its accompanying bed of sand, may be traced down, by scraping away the surface, for about ten feet, when you will discover that it rests unevenly upon the beds below, which, instead of being horizontal, slope (_dip_) in a n.n.e. direction, making an angle of about ° with the floor of the pit; the gravel therefore rests successively upon the upturned ends of the lower beds, and, geologically speaking, is "unconformable" to them. now as these underlying rocks were of course originally deposited in an horizontal position, they must have been pushed up and the upper parts worn away (_denuded_) before the gravel was deposited on them, for the accomplishment of which process an amount of time must have elapsed that it would be impossible to reckon by years. when we come to examine these lower beds, we find first a stratum of stiff dark-brown clay containing fossils disposed in layers: those near the outer surface have been rendered so brittle by the weather, that it is necessary to make use of the pick end of the hammer and dig a little way into the face of the section before we come upon some which will bear removal by cutting them out with a knife. pack them in a tin with bran, or, where much clay still adheres to them, wrap them in paper. the true top of this bed is not visible, being concealed beneath a heap of earth in the corner of the pit, but we can see and measure about six feet of it. the next bed in order is a light brownish band of sandy clay that splits along its layers into thin pieces or "_laminæ_," whence we may describe it as a sandy, _laminated_ clay. on the freshly split surface of one piece we see scattered a number of small darker brown fragments; an examination with a pocket lens clearly shows that these are little bits of leaves and stems, with here and there a more perfect specimen. these beds must have been deposited in the still waters just off the main stream of a large river which brought the plants floating down to this spot, where they became water-logged and sunk; so, too, if you examine the shells in the bed immediately above, you will see that they are very like though not the same as those which at the present day love to dwell in the mud off the estuaries of big rivers in warmer parts of the globe; hence we discover that at some far distant period a big river, but one which had no connection with that running close by, once flowed over this very spot. on tracing the leaf-bed down, we come all at once, at about three feet from its upper surface, upon a narrow band one or two inches thick of a substance composed of numerous bits of sticks and stalks closely matted together and partially mineralized. vegetable matter in this form is known as lignite, and is one of the first stages towards the formation of coal out of plant remains. below this lignite band we find our leaf-bed getting sandier and sandier, and losing all trace of the plants by degrees till it becomes almost pure sand. here and there, however, it contains some curiously shaped masses, which, when broken through with the hammer, seem composed of nothing but the same grains of sand cemented together into a hard mass. in one there is, however, a curiously shaped hollow, which, upon examining it closely, you will see is a perfect cast of a small shell that has itself disappeared. a drop of acid on it fizzes away and sinks in between the grains of sand which in this spot become loose. a mass of sand or particles of clay thus cemented together, be it by iron, lime, or any other substance, is termed a "_nodule_" or "_concretion_," and in this particular instance has been formed as follows:--the rain-water falling on the sand where it comes to the surface sinks in and filters through the bed. now there is always a certain amount of carbonic acid in rain-water, and this acid acted on the carbonate of lime of which the shell was composed, dissolving and dispersing it amongst the neighbouring grains of sand where it was re-deposited, cementing them together as we have seen. the bottom of this bed of sand we find to be just fifteen feet from the lignite band when measured at right-angles to the bed, and it is succeeded by a hard greyish rock, which requires a smart blow of the hammer to break it, but the surface of which, where it has been exposed to the weather, is much crumbled ("_weathered_"), and breaks readily into small pieces. it is easily scratched with the point of a knife, and therefore is not flint; moreover, it fizzes strongly when touched with acid--hence there is a great deal of carbonate of lime in it, and we know that it is limestone. limestones are very largely, sometimes almost entirely, made up of the calcareous portions of marine creatures, such as the hard parts of corals, the tests of sea-urchins, the shells of mollusca, etc., welded, so to speak, into one mass by the heat, pressure, and chemical changes which the bed has undergone since its deposition at the bottom of the sea. there would be every reason, therefore, one might suppose, to expect a number of fossils in this bed; but, alas! disappointment awaits the young explorer, for with the exception of chalk and a few other limestones, these rocks are generally of such uniform texture that on being struck with the hammer they split through fossils and all, the fractured surface only too frequently showing nought save a few obscure markings. but what we fail to accomplish in our impatience, nature effects by slow degrees, and if you will turn over the weathered pieces and blocks lying about, you will soon find plenty of fossils sticking out all over them; by a judicious use of hammer and chisel any of these may be detached and added to your stock, each being separately packed in paper and the locality written on the outside. some seventy or eighty feet is all that is visible of this limestone; the rest is unexcavated. before leaving the pit, it will be as well to select such rock specimens as you wish to place in your cabinet, trimming them to the required size on the spot, for should you, as is not unlikely, spoil two or three, you can readily pick a fresh one. having secured our specimens, we will take a look at our note-book, to see if we have noted all the details we require. if so, our entries should run something as follows:--first, we have made a rough sketch of the position of the beds, carefully numbering each one; then follow our notes on the individual beds, preceded by numbers corresponding with those in the sketch, thus:-- . surface soil ft. . river gravel, including a lenticular mass of } . sand, with land and fresh-water shells and bones of } ft. animals } . stiff dark-brown clay, with estuarine shells ft. seen. . light-brown sandy clay, with leaves and stems of plants ft. . band of lignite in. . same as , passing into-- } . pure sand, with layers of concretions containing casts } of shells } ft. . dark-grey limestone, with numerous fossils ft. seen. beds to dip at an angle of ° to the n.n.e. our imaginary pit is of course only a sort of geological juan fernandez, but it will serve in some degree to illustrate the method of dealing with various rocks and fossils when met with in the field, and how they may best be collected and carried home. a few additional suggestions where to look for fossils may, however, be given here. to begin with, i never neglect to search the fallen masses, especially their weathered surfaces, or to look carefully over the heaps of quarried materials, whatever they may happen to be, piled on the floor of the pit. in working at the beds themselves, remember that fossils frequently occur in layers which of course represent the old sea-bottom of the period; to find these, it is necessary to follow the beds in a direction at right angles to their stratification, till you arrive at the sought-for layers, or _zones_. do not be surprised, when collecting from a formation you have never before studied, if the fossils are not at first apparent, though many are known to be present. the eye requires a few days in which to become accustomed to its fresh surroundings, and when the same spot has been carefully hunted over every day for a week, it is astonishing what a quantity of fossils are discernible where not one in the first instance was recognised. how to prepare the specimens for the cabinet. the first thing to be done on unpacking our specimens is to pick out those which require the least attention, and get them out of the way. these will be your rock specimens, which, if they have been trimmed properly in the pit, will not need much further manipulation; a word or two, however, as to the best method of proceeding when it is desirable to reduce a specimen, will not be out of place. if you wish to divide it in two, or detach any considerable portion, the specimen may, while held in the hand, be struck a smart blow with the hammer; as, however, it not frequently happens that even with the greatest care the specimen under this treatment breaks in an opposite direction to that required, it is advisable to adopt a somewhat surer method, namely, to procure a block of tough wood, and in the centre bore a hole just large enough to receive the shank of the cold chisel, and thus hold it in an upright position with the cutting edge uppermost; placing the specimen on this, and then hitting it immediately above with the hammer, it may be fractured through in any required direction. to trim off a small projection, hold the specimen in your hand with the corner towards you and directed slightly downwards, then with the edge of the striking face of the hammer hit it a smart blow at the line along which you wish it to break off; the object of inclining the specimen is to make sure that the blow shall fall in a direction inclined away from the portion you wish to preserve, a _modus operandi_ which it is necessary to bear well in mind if you would not spoil many a choice specimen. anything beyond very general directions, however, it is impossible to give in such matters as this: experience, and a few hints from those who have themselves had practice in collecting and arranging specimens, are worth more than any written description, however lengthy and elaborate. having reduced your specimen to the required size and shape, the next thing to be done is to write a neat little label for it--the smaller the better--stating, first the nature of the specimen, secondly the geological formation to which it belongs, thirdly the locality from which it was procured, and fourthly the date when acquired, thus-- limestone. lower carboniferous. quarry, mile n.w. of ---- . . -. ruling a neat line at the top and bottom (red ink lines give a more finished appearance than black). when the label is dry, damp it to render it more pliant, and gum it on to the flattest available surface of the specimen, pressing it well into any small inequalities that it may hold the firmer. a small quantity of pure glycerine (about an eighth part) should be added to the gum before use, in order to prevent its drying hard and brittle. the specimen is now ready to place in its tray and be put away in the cabinet. in the next place, pick out the fossils which you obtained from the limestone. with the cold chisel set in its block of wood, and the trimming hammer, remove as much of the surrounding rock (_matrix_) as you can without damaging the fossil, and with a smaller chisel any pieces that may be sticking to and obscuring it. fossils in soft limestone, such as chalk, are best cleaned with an old penknife, and needles fixed into wooden handles, and finished off by the application of water with a nail-brush. should you have the misfortune to break any specimen in the process of trimming, it should at once be mended. the most effectual cement for this purpose is made by simply dissolving isinglass in acetic acid, or, where the specimen contains much iron pyrites, and there would be a danger in starting decomposition, shellac dissolved in spirits of wine. when, however, neither of these are handy, chalk scraped with a penknife into a powder, and mixed with gum to the consistency of a thick paste, answers admirably. failing this, however, gum alone will frequently suffice. the next thing is to place the like kinds together in their several trays, writing a label, as before, for each tray, but leaving a blank space at the top for the insertion of the name when ascertained. the commoner sorts may be named from the figures of them given in the text-books (see list at the back of the title page); but failing this, it will be the best plan to seek the help of any friends who have collections, or to take the fossils to some museum, and compare them with the named specimens there exhibited. the label may be laid at the bottom of the tray with the fossils loose on the top of it, each fossil being marked with a number corresponding to one on the label. another plan is to fasten the label by one of its edges to the side of the tray; or, if the fossils are small and mounted on a piece of card fitting into the tray, it may be gummed with them to the card. now let us take the shells we obtained from the dark-blue clay, with those and the bones from the old river bed up above. gently turn them out of the tins, in which they were packed in the quarry, on to a paper or the lid of a card-board box, and with a pair of forceps pick them carefully out of the bran, and place them in large shallow trays, taking care not to mix those from the different beds. as we found when collecting them, these shells are extremely brittle from loss of animal matter, and our first object is therefore to harden them by some process, so that they will bear handling. to accomplish this you must get a saucepan, one of those wire contrivances for holding eggs when boiling, or a big wire spoon, such as formerly was used for cooking purposes, a packet of gelatine, and some flat pieces of tin, which last are easily procured by hammering out an old mustard or other tin, having previously melted in a gas flame the solder wherewith it is joined. half fill the saucepan with clean water, and put in as much gelatine as when cold will make a stiff jelly; melt this over the fire, placing the fossils meanwhile in a warm (not hot) corner of the fire-place; then when the gelatine is quite dissolved, pile as many of them, whole or in pieces, into the egg-boiler, or spoon, as it will contain, hold them for a second in the steam, and then lower them gradually into the hot gelatine until it completely covers them. little bubbles of air will rise and float on the surface. as soon as these cease to appear, raise the fossils above the surface and allow them to drip; then pick them up one by one with the forceps, and spread them out on pieces of tin before the fire, but not too close to it. as soon as their exterior surfaces become dry, and before the gelatine gets hard, they should be taken up (they may be handled fearlessly now), and the superfluous gelatine sticking to the surface gently removed with a camel's-hair brush dipped in clean warm water; otherwise, when dry, they present an unnatural varnished appearance, and have a tendency, on small provocation, to become unpleasantly sticky. small bones may be treated in like manner, but for large ones, weak glue is to be preferred to gelatine, which is only suitable for the finer and more delicate objects. where it is desired to harden only a few things, it is better to mix the gelatine in a gallipot, which can be heated when required by standing it in a saucepan of water on the fire. in any case the gelatine need never be wasted, as it will keep almost any length of time, and can therefore be put by for future use. in default of the egg-boiler or wire-net spoon, an equally useful plan is to make a strainer from a piece of perforated zinc by turning up the edges all around, and attaching copper wire to it by which to lower the fossils into the gelatine, and raise them again. when the fossils are quite dry they can be sorted, and those which have come to pieces may be mended with diamond cement (_i.e._ isinglass dissolved in acetic acid), and then properly labelled and placed in trays, or mounted as previously described. to the plant remains and lignite there is little that can be done beyond trimming them to suit the trays. should there be much iron pyrites in the lignite, it is sure, sooner or later, to decompose, when all that can be done is to throw it away. in the case, however, of valuable fruits and seeds, such as those from the london clay of sheppey, it is worth while to preserve them, if possible, in almost the only way known, viz. by keeping them in glycerine in wide-mouthed stoppered bottles, or by saturating them with paraffin. having prepared the specimens for the cabinet, the next thing is to arrange them in proper order. there are several ways of doing this, but for those who have not had much experience the following plan will be found the best:--group the specimens according to the formations to which they belong, and arrange these groups in proper sequence (_vide_ table, p. ); then take each group, and arrange the specimens it comprises in columns. beginning at the top of the left-hand corner, place first the specimens of the rock itself, and under it any examples of minerals, concretions, etc., found in that rock; next the fossil plants, if any; and finally, such animal remains as you have arranged according to their zoological sequence, beginning with the lower forms (_vide_ table, p. ). unless cramped for room, each formation should begin a new box, its name being written on a slip of paper and placed at the head of the columns of trays. a label setting forth its contents should be fixed outside each of the boxes, which can then be put away on your cupboard shelves. table of the principal fossiliferous strata arranged in chronological order. _land plants._-----------+ _invertebrata._--------+ | _fishes._------------+ | | _amphibia._--------+ | | | _reptiles._------+ | | | | _birds._-------+ | | | | | _mammalia._--+ | | | | | | _man._-----+ | | | | | | | | | | | | | | | | | | | | | | | {alluvial deposits, | | | | | | | | _quaternary, { river valley | | | | | | | | or { gravels and | | | | | | | | pleistocene._ { cave deposits. | | | | | | | | {drift and glacial | | | | | | | | { deposits. v | | | | | | | | | | | | | | _cainozoic, {pliocene. | | | | | | | or {miocene. | | | | | | | tertiary._ {eocene. | | | | | | | | | | | | | | { {chalk. | | | | | | | m { _cretaceous._ {upper greensand. | | | | | | | e { {gault. | | | | | | | s { | | | | | | | o { _neocomian._ {lower greensand. | v | | | | | z { {wealden. | : | | | | | o { | : | | | | | i { { {purbeck. | : | | | | | c, { {_upper._{portland. | : | | | | | { { {kimmeridge clay. | : | | | | | or { { | : | | | | | { { _mid._ {coral rag. | : | | | | | s { { _oo- { {oxford clay. | : | | | | | e { {lites._{ | : | | | | | c { { { {cornbrash and | : | | | | | o { { { { forest marble. | : | | | | | n { _jurassic._{ {_lower._{great oolite. | : | | | | | d { { { {fullers' earth. | : | | | | | a { { { {inferior oolite. | : | | | | | r { { | : | | | | | y { { lias. | : | | | | | | : | | | | | { {trias, or new | : | | | | | p { _poikilitic._ { red sandstone. v ? v | | | | a { {permian. | | | | l { | | | | Æ { {coal measures. v | | | o { {millstone grit | | | z { _carboniferous._ { and yoredale | | | o { { rocks. | | | i { {carboniferous | | | c, { { limestone, etc. | | | { | | | or { devonian and old | | | { red sandstone. | | | p { | | | r { {ludlow beds. | | | i { {wenlock beds. | | v m { _silurian._ {woolhope beds. | | a { {tarannon shale. | | r { {llandovery or may | | y. { { hill group. v | { | { {bala and | { { caradoc beds. | { {llandeilo flags. | { {arenig group. | { _cambrian._ {tremadoc slates. | { {lingula flags. | { {menevian beds. | { {longmynd and | { { harlech group. v { : { pre-cambrian and : { laurentian. ? notes on the different formations mentioned in the table. recent.--the alluvial deposits of most river valleys and some estuaries still in course of formation, containing fossil shells and mammals, all of living species. quaternary, post-pliocene, or pleistocene.-- . including the raised beaches around the coast, the older gravels of river valleys and the cave deposits, in all of which the shells are identical with those living in the rivers and seas of to-day, whilst the animals are many of them extinct, only a few being now found living on the spot. . the glacial drifts that cover all england north of the thames, and which consist of sands, gravels, and clays, full of big angular stones frequently flattened on one side, scratched and sometimes polished from having been fixed in moving ice and forced over other rocks. a very interesting collection of these "boulders," as they are called, can be easily made, for they belong to almost every formation in england, and have some of them been brought from great distances, whilst the number and variety obtainable from a single pit is astonishing. cainozoic, or tertiary.--beds of this age, in england at all events, are for the most part made up of comparatively soft rocks, gravels, sands, and clays, and are found in the eastern and south-eastern counties. they are divided into-- . pliocene, mainly consisting of a series of iron-stained sands, with abundant shell remains, and locally known as "crags." the shells are very partial in their distribution, the beds in places being almost entirely made up of them, whilst in others scarcely one is to be found. the great majority are of the same species as many still living. the pliocene is subdivided into three groups:-- _a._ the _norwich crag series_, sometimes called the "mammaliferous crag," as at its base the bones of mastodon, elephant, hippopotamus, rhinoceros, and some deer have been found. the shells in it are such as still abound on the beaches of the eastern coast to-day--whelks, scallop shells, cockles, periwinkles, etc. _b._ the _red_ or _suffolk crag_, its two names indicating its characteristic colour (a dark red-brown) and chief locality. from the base are obtained the celebrated phosphatic nodules miscalled "coprolites," whence is manufactured an artificial manure, and with them are found the rolled and phosphatized bones and teeth of whales, sharks, etc. amongst the shells the reversed whelks (_fusus contrarius_), _fecten opercularis_, _pectunculus glycimeris_, several kinds of _mactra_ and _cardium_, etc., are the commonest. walton-on-the-naze, felixstowe, and woodbridge are the best known localities. _c._ the _white_ or _coralline crag_ is generally of a pale buff colour, and is in places almost entirely composed of the remains of polyzoa. these (formerly called corallines, whence the name coralline crag) are beautiful objects for a low-power microscope, or pocket lens, and are easily mounted in deep cells on slides. the bits of shell and sand that stick to them should be carefully removed with the point of a needle. a very large number of shells occur in this crag: of bivalves, the _pecten_ is very abundant, and its valves are frequently thickly grown over with polyzoa; _cyprina islandica_, _cardita senilis_ are also plentiful; and of univalves, the genus _natica_ is common. the coralline crag is best seen in the neighbourhood of aldborough, orford, woodbridge, and other places in suffolk. . miocene, possibly represented in the british isles by a small patch of clays and lignites at bovey tracey. . eocene, divided into-- _a._ _upper eocene_, consisting of a series of very fossiliferous sands, clays, and limestones, exposed in the cliffs at the eastern and western ends of the isle of wight and on the neighbouring coast of hampshire. they are partly of freshwater origin, when they contain the remains of freshwater shells such as _limnoea paludina_, _planorbis_, etc.; partly of marine origin, when shells belonging to such genera as _ostrea_, _venus_, etc., take their place; partly of estuarine, when the brackish water mollusca are found with bones and scutes of crocodiles and tortoises. _b._ _middle eocene_, or the _bagshot beds_, composed of sands and clays. the beautiful coloured sands of alum bay, the sands of the surrey and hampstead heaths, are familiar examples of the beds of this age. very few fossils indeed have been found in them. the clay-beds on the contrary as seen at barton and hordwell on the hampshire coast and again in the isle of wight, abound with shells belonging to genera such as _conus_, _voluta_ and _venus_, that inhabit warm seas. with them are the nummulites, looking externally very like buttons, but on the inside divided into innumerable chambers in which the complex animal that formed the nummulite dwelt. _c._ _lower eocene_, the well-known london clay, may almost be said to compose this division, for the underlying sands, gravels, and clays are in mass comparatively insignificant. the london clay contains plenty of fossils, only as they are disposed in layers (_zones_) at a considerable distance apart, they are not often hit upon. layers of septaria or cement-stones are of frequent occurrence. sheppy is the great locality for london clay fossils, as the sea annually washes down large masses of the cliffs and breaks them up on the beach. a great many fossil fruits and seeds, remains of crabs, shells of nautili, volutes, and other mollusca, besides turtles, a species of snake, a bird with teeth, and a tapir-like animal, have at different times and in various places been found in this deposit, which sometimes attains a thickness of over ft. the "bognor rock" is a local variety of the basement bed of this formation. [illustration: _aturia zic-zac_ (from the london clay).] the mesozoic or secondary rocks embrace a series of limestone, clays, sands, and sandstones that on the whole are well consolidated. the main mass of them lies to the west of a line drawn across the map of england from the mouth of the tyne, in northumberland, southwards to nottingham, and thence to the mouth of the teign in devonshire. in the south-eastern counties they underlie the tertiary rocks of the london and hampshire basins, as they are called, at no great depth from the surface. outlying patches of secondary rocks occur in scotland, where they are found near brora on the east coast, and in the islands of skye and mull on the west. in ireland they are scantily represented round about the neighbourhood of antrim. the secondary rocks are divided into-- . cretaceous. _a._ the _chalk_ is too well known to need description, though technically it may be described as a soft white limestone chiefly built up of the microscopic shells of _foraminifera_, and characterized in its upper part by nodules and bands of flint. these flints frequently inclose casts of fossils (sponges, sea-urchins, etc.), and sometimes shells themselves. fossils, too, are fairly abundant, scattered throughout the mass. amongst the commoner may be noticed the sea-urchins, such as the "sugar loaf" (_ananchytes_) and the heart-shaped _micraster_, the brachiopods or lamp-shells (_terebratula_, _rhynchonella_), a "thorny oyster" (_spondylus spinosus_), besides ammonites, belemnites (part of the internal shell of a kind of cuttle-fish), and the teeth of several species of sharks. altogether the chalk is about , feet thick. [illustration: _ammonites various_ (from the chalk).] _b._ _upper greensand_ is a series of greenish-grey sands and sandstones. the green colour, on close inspection, is seen to be due to the presence of innumerable small green grains of a mineral called glauconite. these are frequently casts of the chambers of the very same foraminifera that the chalk is so largely composed of. [illustration: _rhynchonella depressa_ (a brachiopod, from the upper greensand).] nodules and layers of "chert" (an impure kind of flint) occur in it, whilst in places it forms a hard rock called "firestone." the commonest fossils are brachiopods, very similar to those in the chalk, a scallop-shell with four strongly marked ribs on it (_pecten quodricostatus_), an oyster with a curved beak (_exogyra columba_), and a pear-shaped sponge (_siphonia pyriformis_). the upper greensand is better seen at places in the southern part of the isle of wight, in cliffs on the dorsetshire coast, in wiltshire, at sidmouth, and in some parts of surrey. [illustration: _ammonites auritus_ (from the gault).] _c._ _gault_, a stiff blue clay abounding in fossils: ammonites often retaining their pearly shell; belemnites, a bivalve with very deep furrows on it (_inoccramus sulcatus_), and its first cousin (_i. concentricus_, p. ), in which the ridge-like markings correspond with the lines of growth, besides many others, may be obtained in abundance from it. layers of phosphatic nodules occur at irregular intervals. the gault is best studied at east wear bay, near folkstone; it may also be seen in dorsetshire, wiltshire, and cambridgeshire; lately it has been found as far west as exeter. . neocomian. _a._ the so-called _lower green sand_, named in contradistinction to the _upper green sand_, includes a series of iron stained sands, sandstones and clays of great thickness. the clayey beds are seen at atherfield in the isle of wight, and at nutfield in surrey, while the sandy beds are met with at speeton, at folkestone, and near reigate. besides brachiopods and oysters, these beds have furnished a species of _perna_ (_p. mulleti_), an elongated mussel (_gervillia anceps_), a pretty _trigonia_ (_t. cordata_), some _ammonites_ and nautili, with the teeth and bones of big reptiles. the celebrated "kentish rag" and the sponge gravels of farringdon are of this age. _b._ _wealden._ the main mass of these rocks occupies the area inclosed between the north and south downs, and forms the valley of the weald, whence they take their name. they consist of a series of sands, sandstones, clays, and shelly limestones that were deposited in the delta and off the mouth of a big river. the shells in them belong to freshwater genera, _cyrena_, _unio_, _paludina_, etc. bones of a huge lizard that hopped along on his hind legs (_iguanodon_), and those of crocodiles, etc., are from time to time brought to light. the wealden rocks occur also on both eastern and western sides of the isle of wight, and in dorsetshire. [illustration: _inoceramus concentricus_ (from the gault).] . oolites (or roe-stones) are so named because the characteristic limestones of this formation resemble very much the roe of a fish. the small round grains, of which the typical examples are built up, when cut or broken through will be seen to be formed of numerous layers of carbonate of lime, disposed like the coats of an onion, around some central nucleus, generally a grain of sand, a fragment of coral, or the shell of one of the foraminifera. they are divided into upper, middle, and lower oolites, and these again are subdivided as follows-- upper oolite. _a._ _purbeck beds_, a series of fresh-water, with a few estuarine, or marine beds, which in point of fact connect the deposits we are next coming to with the wealden just passed. they contain numerous fresh-water shells--_paludina_, _physa_, _limnæa_, etc., with the microscopic valves of the little fresh-water crustacean _cypris_, whose descendants are abundant in the rivers and lakes of to-day. an oyster occurs in the "cinder bed" and plant remains in the "dirt beds." but the purbecks are best known for the numerous remains of small mammals (_plagiaulax_) allied to the kangaroo rat, at present living in australia. _b._ the _portland stone and sand_, which come next in order, are largely quarried in the island whence they take their name. the quarrymen point out fossils in the stone, which they call "horses'-heads" and "portland screws." the former is the cast of a _trigonia_ shell; the latter, that of a tall spired univalve (_cerithium_). in wiltshire, a coral (_isastrea oblonga_) is found in the sandy beds, the original calcareous matter of which has been replaced by silex. _c._ _kimmeridge clay._ this, by the pressure of the rocks subsequently deposited on it, has in greater part been hardened, and possesses a tendency to split in thin layers, and hence is termed by geologists a shale. it is seen at various points between kimmeridge on the dorsetshire coast and the vale of pickering in yorkshire, and forms broad valleys. the principal fossils in it are ammonites, a triangular-shaped oyster (_ostrea deltoidea_), and one resembling a comma (_exogyra virgula_). middle oolites. _a._ the _coral rag_, or _coralline oolite_, comprises a most variable set of beds, but principally a series of limestone, with fossil corals still in the position in which they grew, and resembling in form the reef-building corals of the pacific. they rest on _b._ _oxford clay_, a dark blue or slate-coloured clay without any corals, but containing a great many _ammonites_ and _belemnites_. the _kelloway rock_, a sandy limestone at the base of the oxford clay, is well developed in yorkshire, and furnishes amongst other fossils a large belemnite and an oyster (_gryphæa dilatata_). lower oolites. _a._ _cornbrash_, a very shelly deposit of pale-coloured earthy, and rubbly or sometimes compact limestone with plenty of fossils. the commonest are brachiopods, limas, oysters (_ostrea marshii_), pholadomyas and ammonites. it is best seen in dorsetshire, somersetshire, and near scarborough in yorkshire. _b._ _forest marble_ and _bradford clay_. the former is an exceedingly shelly limestone, often splitting into thin slabs. on the surfaces of some of the beds may be seen the ripple marks the sea made countless years ago, and the tracks of worms and crabs that dwelt in the mud or crawled on its surface at a time when it was soft mud. the bradford clay is a very local deposit, taking its name from bradford in wiltshire, where it is most developed, and its characteristic fossil is the pear-shaped encrinite or "stone-lily" (_apiocrinus parkinsoni_). _c._ the _great_ or _bath oolite_, comprising a series of shelly limestones and fine oolites, or freestones. the latter are largely quarried in the neighbourhood of bath, and used for mantelpieces and the stone facings of windows. the great oolite is rich in univalve mollusca, amongst which may be noted a limpet (_patella rugosa_) and the handsome, tall-spired _nerinæa voltzii_, numerous bivalves belonging to the genera _pholadomya trigonia_, _ostrea_ (_o. gregaria_), and _pecten_, besides brachiopods (_terebratula digona_, which looks very like a sack of flour, and _t. perovalis_, etc.). at the base of the great oolite are the "stonesfield slates," so-called--a series of thin shelly oolites, etc., that split readily into very thin slabs. they are principally of interest to geologists on account of the discovery in them of the remains of small insect-feeding and possibly pouched mammals. with these are associated the bones of that big reptile the _megalosaurus_; the flying lizards called pterodactyles; fish teeth and spines; lamp shells; oysters, a _trigonia_ (_t. impressa_); and the impressions of insects, including a butterfly, and of plants. _d._ _fullers' earth_, a clayey deposit occurring in the southwestern parts of england, but not in the north. it abounds with a small oyster (_o. acuminata_) and brachiopods (e.g. _terebratula ornithocephala_), etc. _e._ _inferior oolite_ (including the midford sands). as these beds are followed across the country from the south-west of england to yorkshire, they are found to change greatly in character. limestone and marine beds in the south are replaced by sandy and estuarine beds in the north. amongst other fossils from beds of this age may be found several echinoderms, a crinkly lamp shell (_terebratula frimbriata_), and a spiny one (_rhynchonella spinosa_), bivalves belonging to the genera _ostrea_, _trigonia_, _pholadomya_, etc., and some very handsome ammonites (e.g. _a. humphresianus_). [illustration: _ichthyosaurus_, or fish-lizard (from the lias).] [illustration: _plesiosaurus_ (from the lias).] . lias. this for the most part consists of very regular alternations of argillaceous (clayey) limestone and clay, or shale. it is of great thickness, and hence for convenience has been divided into (a) _upper lias_, (b) _middle lias_ or _marl-stone_, and (c) _lower lias_. a large number of fossils are to be found in it. lyme regis and whitby are perhaps the best known localities; the former, on account of the great number of specimens obtained of the huge fish-lizard (_ichthyosaurus_, p. ), and long-necked _plesiosaurus_ (p. ), besides numberless fish; whilst the latter is renowned for its jet (or fossilized wood) and its "snake-stones" (_ammonites_), concerning which curious old stories are told. _ammonites_ are plentiful in the lias, which has been subdivided into zones, or layers, named after the ammonite occurring in greatest numbers in that particular zone. there is one thin limestone band in the marlstone composed entirely of the shells of _ammonites planicostatus_. a curious kind of oyster (_gryphæa incurva_), locally known as the devil's toenail, a huge _lima_ (_l. gigantea_), a magnificent encrinite (_extracrinus briareus_), and numerous other fossils, are also to be obtained by patient search. [illustration: _belemnitas elongatus_(from the lias).] . rhætic, penarth beds, or white lias. these beds are not of any considerable thickness, but are very persistent, and of great interest, inasmuch as they yield the remains of the oldest known mammal (_microlestes_), a small insect-feeder. they are composed of limestones, shales and marls (_i.e._ limey clays), and are best studied in somersetshire and dorsetshire. the "landscape marble" belongs to this formation, which also contains a bone bed, or thin layer made up of the bones and teeth, etc., of fish. shells are not numerous, though the casts of one species (_avicula contorta_) is plentiful. . trias, or new red sandstone, a thick series of sandstones and marls, the great mass of which forms the subsoil of the western midland counties, birmingham being nearly in the centre, thence they extend in three directions, one branch passing towards the north-west, through cheshire, to the sea at liverpool, reappearing on the coast line of lancashire, westmoreland, and cumberland, where it also forms the valley of the eden. another branch extends through derby and york to south shields, whilst the third may be traced southwards in isolated patches down into devonshire. there are scarcely any fossils in it, but in worcestershire and warwickshire the bivalve shell of a small crustacean (_estheria minuta_) occurs in the upper beds; whilst now and again the teeth and bones of some strange amphibians (_labyrinthodon_), or the impressions of their feet (_cheirotherium_) where they crawled on the then soft mud of the foreshore, are found. the trias is divided into upper trias or keuper, and lower trias or bunter. the middle beds (muschelkalk), which are found in germany, where they contain plenty of fossils, are wanting in this country. in the lower beds of the keuper, layers of rock salt, sometimes of great thickness, occur, whilst casts (called pseudomorphs) of detached salt-crystals are found abundantly in the sandy marls. northwich, nantwich, droitwich, and several other towns in cheshire and worcestershire, are famed for their salt works, the salt being either mined or pumped up as brine from these beds. [illustration: _ceratites nodosus_ (from the muschelkalk).] palÆozoic or primary.--beds of this age generally possess a more crystalline and slaty structure than any of those already mentioned, are usually more highly inclined and disturbed, and form for the most part more elevated ground. they are the principal store-houses of our mineral wealth, containing as they do coal, iron, and other metals. the palæozoic rocks are found in england to the north and west of the secondary series, beneath which they disappear when traced to the south-east. wales, and the greater part of scotland and ireland, consist of beds of this age. . permian. under this term are included beds of red sandstones and marls, closely resembling those of trias, and like them containing but few fossils, as well as a very fossiliferous limestone, known as the magnesian limestone, from the abundance of magnesia it contains. a pretty polyzoan (_fenestella retiformis_), a spiny brachiopod (_productus horridus_), various genera of fish, chiefly found in a marl state underlying the limestone, some labyrinthodonts and plant remains, are the principal forms met with in this formation. . carboniferous. this, from a commercial point of view, is the most important of all the formations, comprising as it does the coal-bearing strata. it is subdivided into-- _a._ _coalmeasures_, a series of sandstones and shales with which are interstratified the seams of coal, varying in thickness from six inches to as much in one instance as thirty feet. coal is the carbonized remains of innumerable plants, chiefly ferns and gigantic clubmosses, that grew in swamps bordering on the sea-coast of the period. each coal seam is underlain by a bed of clay called "under-clay," containing the roots of the plants that grew on it. some of the best impressions of ferns, etc., are to be obtained in the shaley beds forming the roof of the coal seam; many good specimens, however, are to be got by searching the refuse heap at the pit's mouth. besides plants, the remains of fish are abundant in some of the beds of shale. and in nova scotia the bones of air-breathing reptiles and land snails have been discovered. cockroaches and other insects were also denizens of the carboniferous forests. the following are the principal coalfields:-- . northumberland and durham coalfield. . south lancashire coalfield. . derbyshire coalfield. . leicestershire and staffordshire coalfields. . south wales coalfield. . bristol and somerset coalfields. _b._ _millstone grit_ or _farewell-rock_. the former term explains itself, the latter designation has been applied to it in the southern districts, because when it is reached, then good-bye to all workable coal-seams. it consists of coarse sandstones, shales, and conglomerates with a few small seams of coal. fossils are not very common in it. _c._ yoredale rocks, a series of flagstones, gritstones, limestones and shales, with seams of coal, occurring in the northern counties. it is underlain by-- _d._ _carboniferous_ or _mountain limestone_, which in places is upwards of , feet thick, and full of fossils. the stems of encrinites, or "stone-lilies," corals, brachiopods (_e.g._ _productus_, _orthis_, etc.), and mollusca, including some cephalopods, like _goniatites_ and the straight nautilus (_orthoceras_), with fish teeth, etc., go to compose this tough, bluish-grey limestone which is largely quarried for marble mantlepieces, etc. _e._ the _tuedian group_ in the north, and _lower limestone shale_ in the south, follow next, and consist of shales, sandstones, limestones, and conglomerates, varying greatly in different districts, and containing few fossils. . devonian or old red sandstone. to this age are assigned a perplexing series of strata, the principal members of which consist of (_a_) a thick limestone, well seen in the cliffs and marble quarries of south devon, and full of fossil-corals (_e.g._ _favosites polymorpha_ [or _cervicornis_]) brachiopods, and mollusca, etc. _b._ a series of sandstones, slates, and limestones in north devon containing trilobites (_phacops_, _bronteus_, etc.), brachiopods, and other fossils. _c._ the _old red sandstone_ of wales, the north of england, and scotland, consisting of red and grey sandstone and marly beds, with remains of fish. these fish, unlike most now living, were more or less covered with hard external plates, and possessed merely a cartilaginous skeleton. in one set of individuals, indeed (_pterichthys_), the armour plates formed quite a little box. these creatures propelled themselves by means of two arm-like flippers, rather than fins. they were but a few inches long, and appear pigmies in contrast to the strange half-lobster-like crustacean, _pterygotus_, that lived with them, and attained sometimes as much as five feet in length. . silurian. named by sir roderick murchison after a tribe of ancient britons that dwelt in that part of wales, where these rocks were first observed. some of murchison's lower silurian beds were included by professor sedgwick in his cambrian, of which we shall have to speak next; and as these two geologists never could agree on a divisional line between their respective formations, and since succeeding observers have followed sometimes one and sometimes the other method of classification, considerable confusion has resulted. here, however, for several reasons, we propose to follow sedgwick's arrangement; and hence, under the term silurian, retain only murchison's upper beds. they consist of a series of sandstones, gritstones, conglomerates, shales, limestones, etc. amongst the more important fossils, which are very abundant in the limestones, are various corals (_e.g._ the chain-coral _halysites_), star-fish, crinoids, trilobites (_phacops_, etc.), polyzoa, brachiopods and mollusca, especially cephalopoda (_orthoceras_, _nautilus_, etc.). these rocks occur principally in the border land between england and wales, and the adjacent counties; but are also represented in westmoreland, scotland, and ireland. their principal subdivisions are given in the table on p. . [illustration: trilobite (_asaphus candatus_), (from the silurian).] [illustration: _orthoceras subannulatum_ (from the silurian).] . cambrian. under this term, derived from the old name for wales, are included many sandstones, grits, slates and flags, with here and there a limestone band. they form the greater part of the western counties of wales, where they rise to a considerable height above the sea level. the highest hills of westmoreland and more than half of scotland are composed of beds of this age. the fossils, save in the limestone bands, are not easy to find, but in places they are fairly abundant. brachiopods are far more numerous than the mollusca properly so-called. of these, the genus _orthis_ was most abundant at about the close of this period. certain beds of this age have received the name of lingula flags, owing this prevalence in them of the curious brachiopod _lingula_ so like the species now living in some of the warm seas of the tropics. the trilobites included several forms, and one species (_paradoxides davidis_) attained the length of nearly two feet. a few star-fish, some hydrozoans (_graptolites_), and the tubes and casts of annelides and tracks of trilobites, complete the list of more remarkable fossils. the subdivisions of the cambrian rocks will be found in the table on p. . . pre-cambrian.--near st. david's head and some other places in wales, in anglesea, shropshire, etc., some yet older rocks have been found. they are probably for the most part of volcanic origin, but they have been so much changed since they were first deposited, and as hitherto no fossils have been found in them, little is known concerning them. parts of the western coast of northern scotland and the hebrides are composed of a crystalline rock called gneiss, and supposed to be the oldest member of the british strata. no fossils have been found in it. [illustration: skull of _deinotherium giganteum_, a huge extinct animal, related to the elephants (from the miocene of germany).] volcanic rocks. although there are fortunately no volcanoes to disturb the peace of our country at the present day, there is abundant evidence of their existence in the past. not only are some of the beds, especially those of paleozoic age, composed of the dust and ashes thrown out of volcanoes, with here and there a lava flow now hardened into solid rock, but the stumps of the volcanoes themselves are left to tell the tale. the cones indeed are gone, carried off piecemeal by the rain and frosts, and other destructive agencies, in the course of countless ages: not so the once fluid rock within; _that_ cooled down into granite, and though originally below the surface, it now, owing to the removal of the overlying softer strata, forms raised ground overlooking the surrounding country. the granite masses of cornwall, of dartmoor, in the south-west of mt. sorrel; the variety called syenite at malvern and charnwood forest; the basalts of the cheviot hills and of antrim; the volcanic rocks of arthur's seat, edinburgh, and of the islands of skye and mull, etc., are examples of this class of rock. they are of different ages, and belong to different periods of the earth's history, from early palæozoic down to miocene times. table of the principal divisions of the animal kingdom, to show the order in which the fossils should be arranged. invertebrata. _foraminifera_, minute chambered shells like the nummulite. _spongida_, sponges. _hydrozoa_, graptolites, etc. _actinozoa_, corals. _echinodermata_, sea-urchins, stone-lilies, starfish, etc. _annelida_, worm tracks. _crustacea_, trilobites, crabs, etc. _arachnida_, scorpions and spiders. _myriapoda_, centipedes. _insecta_, beetles, butterflies, etc. _polyzoa_ (_bryozoa_) or moss animals. _brachiopods_, lampshells. { _lamellibranchiata_, bivalves. _mollusca_ { _gasteropoda_, univalves. { _cephalopoda_, cuttlefish, ammonites. vertebrata. _pisces_, fish. _amphibia_, labyrinthodonts, frogs, and newts. _reptilia_, reptiles. _aves_, birds. _mammalia_, mammals. works of reference. for naming common fossils. =tabular view of characteristic british fossils stratigraphically arranged.= by j. w. lowry. _soc. prom. christ. knowledge._ . =figures of the characteristic british tertiary fossils (chiefly mollusca) stratigraphically arranged.= by j. w. lowry and others. _london_ (_stanford_). . palÆontology. =the ancient life history of the earth.= by h. a. nicholson. vo. _edinburgh and london._ . =a manual of palæontology.= by h. a. nicholson. nd edition. vols. vo. _edinburgh and london._ . petrology. =the study of rocks.= by f. rutley. (text books of science.) vo. _london._ . field geology. =a text-book of field geology.= by w. h. penning. with a section on palæontology, by a. j. jukes-brown. nd edition. vo. _london._ . geology in general. =the student's elements of geology.= by sir charles lyell, bart. th edition. vo. _london._ . =the principles of geology.= by sir charles lyell, bart. th edition. vols. vo. _london._ . =phillip's manual of geology.= nd edition. by seeley and etheridge. vols., vo. _london._ . =tabular view of geological systems, with their lithological composition and palæontological remains.= by d. e. clement. _london (sonnenschein)._ . british geology. =the physical geology and geography of great britain.= by sir andrew c. ramsey. th edition. vo. _london._ . =the geology of england and wales.= by horace b. woodward. vo. _london._ . =geology of the counties of england and wales.= by w. j. harrison. vo. _london._ . * * * * * popular illustrated scientific books, published by swan sonnenschein & co. uniform with this volume. all fully illustrated. =british butterflies, moths, and beetles.= by w. f. kirby (brit. mus.). crown vo, cloth, _s._ =mosses, lichens, and fungi.= by peter gray and e. m. holmes. crown vo, cloth, _s._ =english coins and tokens.= by llewellynn jewitt, f.s.a.; with a chapter on =greek and roman coins=, by barclay v. head, m.r.a.s. crown vo, cloth, _s._ =flowers and flower lore.= by rev. hilderic friend, f.l.s. illustrated. third edition, demy vo, cloth gilt, _s._ _d._ =the dynamo: how made and how used.= by s. r. bottone. numerous cuts. crown vo, cloth, _s._ _d._ =a season among the wild flowers.= by rev. h. wood. illustrated. crown vo, cloth gilt, _s._ _d._ =history of british ferns.= by e. newman, f.l.s. fifth edition, illustrated. mo, cloth, _s._ =the insect hunter's companion.= by rev. j. greene. third edition. cuts. mo, boards, _s._ =tabular view of geological systems.= by dr. e. clement. crown vo, limp cloth, _s._ swan sonnenschein & co., paternoster square. * * * * * transcriber's notes: as there appear to be section and subsections in the second and third units (shells and fossils) of this book, tables of contents were created for the electronic edition. a number of the images were moved where they split paragraphs. there is a reference to a figure for ancylus; but no fig. was included. the reference to fig. for bullidæ was assumed to be a reference to fig. . bulla ampulla. with the exception of the following items, all page number references in the original text were retained. there are references to two tables on page . the first was listed a "vide table, p. " and the second as "vide table, p. " which appear to refer to the tables on page and respectively. the page references were corrected. species name are assumed to be correct for the time of publication (ca. ). for example, charychium is today listed as carychium. text emphasis _text_ - italics =text+ - bold typographic corrections page correction ---- ------------------------ fond => foot it => if pencil => brush beak => peak tis => its keilia => kellia inever => "i never" crustucean => crustacean transcriber's note: a few typographical errors have been corrected: they are listed at the end of the text. * * * * * [illustration] . _spondylus americanus. (young.)_ . _nautilus pompilius. (young.)_ _g. b. s. jun^r. fecit._ * * * * * a conchological manual. by g. b. sowerby, jun. illustrated by upwards of six hundred and sixty figures * * * * * second edition. considerably enlarged and improved. * * * * * london: henry g. bohn, york street, covent garden. mdcccxlii. * * * * * preface to the first edition. it may be necessary in introducing this little volume, to state, that it is strictly conchological, and that it is compiled for the use not only of those who wish to acquire an elementary acquaintance with the subject, but also of authors and others, who, desirous of extending their knowledge and pursuing their researches, require a book of reference, containing a general outline of what has been done by those who have trodden the same path before them. it has been thought advisable, for general convenience, to arrange the principal part of the information in alphabetical order: adding tables of the systems of lamarck and de blainville, to facilitate the systematic pursuit of the science. persons of the class first alluded to, will find great assistance in the explanation of technical words, their application being further illustrated, in most cases, by a reference to the figures; and, although they might have been multiplied, it is trusted that enough are given for every useful purpose. the definition of the classes, orders, families, and genera, in the system of de blainville, and a tabular view, are presented for the use of those who prefer it, or who wish to compare it with that of lamarck. in the explanation of the figures, will be found a systematic arrangement of shells, according to lamarck, including the names of genera established or proposed since the publication of his system. the descriptions of established genera have been rendered as concise and clear as possible. it is hoped that no essential characters are omitted, and that those living authors, whose proposed generic distinctions have been passed over in a few words, will not have to complain of want of justice in the attempt to interpret their meaning. in most cases the generic name will be found accompanied by its derivation. this has been done, in the hope of assisting the memory by associating the meaning of a term with some peculiarity in the thing described. at the end of each description of a genus, some general observations occur, pointing out the principal character which distinguishes it from others, to which it is nearly allied; and also stating the geographical or geological distribution and habits of the animal. the above descriptions and definitions are illustrated by a series of plates, containing above etchings of nearly as many proposed or established genera, arranged in lamarckian order, so as to show at a glance all the generic forms of each family. and, although from their number, they could not be very highly finished, it is hoped that they will be found characteristic. the compiler cannot replace his pen without acknowledging, with filial gratitude, the kind assistance of one who has sacrificed much of his time in bringing his knowledge and experience to bear upon the correctness and utility of this humble attempt to remove some of the difficulties to which the commencement of this, as well as of every other study, is exposed. preface to the second edition the favourable reception and rapid sale of the first edition of the conchological manual having rendered a second necessary, the author takes this opportunity of explaining the nature of the alterations which have been made. in doing this, he has to thank his friends for their suggestions, which, together with his own increased knowledge and experience, enable him to present a more complete and satisfactory work to the scientific public. for the further convenience of those who are studying the rudiments of the science, an entirely new introduction is given, in which, commencing with the structure and gradual developement of the shell, the author has endeavoured to explain the general principles of conchology in systematical order. this introduction is illustrated by wood-cuts, which will be found greatly to assist the student. the definitions have been rendered more full and complete than before, and the author has profited by some manuscript notes communicated by a scientific friend, to whom he desires to present his humble acknowledgments. upwards of four hundred explanations have been given of words which did not appear in the former edition, three-fourths of which are of generic and subgeneric names. a large number of notes, referring to the geographical distribution of the genera, have been added from the pen of mr. g. b. sowerby, senior. the plates have been carefully improved; and three, containing upwards of eighty figures, have been added. on the whole, it will be found that the amount of matter has been nearly doubled; all the defects, as far as they have been discovered, have been removed, and every means used of making the present edition as useful as possible. * * * * * names of authors abbreviated. _adans._ adanson. author of "voyages du senegal." _bl._ blainville. author of "manuel de malacologie et de conchyliologie," &c. _brod._ w. j. broderip, esq. author of various descriptions of shells in the zoological journal, &c. _brongn._ brongniart. author of "memoire sur les terrains du vicentin, d'italie, de france, et d'allemagne," &c. _brug._ brugière. author of "dictionaire des vers testacés, dans l'encyclopédie," &c. _cuv._ the late baron cuvier. author of "regne animal," &c. _defr._ defrance. contributor to the "annales des sciences naturelles," &c. _desh._ deshayes. author of "coquilles fossiles des environs de paris," &c. _d'orb._ d'alcide d'orbigny. _drap._ draparnaud. author of "histoire naturelle des mollusques terrestres et fluviatiles de la france," &c. _fer._ de ferussac. author of "histoire naturelle des mollusques terrestres et fluviatiles," &c. _flem._ fleming. _gmel._ gmelin. author of an edition of linnæus's "systema naturæ," &c. _guild._ rev. lansdown guilding. _hübn._ hübner. _humph._ the late george humphrey. _lam._ lamarck. author of "animaux sans vertebres," &c. _lin._ linnæus. author of "systema naturæ," &c. _mont._ montague. author of "testacea britannica," &c. _montf._ montfort. author of "histoire naturelle des mollusques," &c. _müll._ müller. author of "vermium terrestrium et fluviatilum," "zoologiæ danicæ," &c. _ranz._ ranzani. author of "considerations sur les balanes," &c. _schum._ schumacher. _sow._ sowerby. the late james. author of "mineral conchology," &c. george brettingham, senr., "genera of shells," "species conchyliorum," &c. g. b. jun. "conchological manual," "conchological illustrations," "thesaurus conchyliorum," descriptions of new shells in the zoological proceedings, &c. _sw._ swainson. author of "zoological illustrations," "exotic conchology," "lardner's cabinet cyclopedia," &c. _turt._ turton. author of "british shells." * * * * * introduction. the science of conchology affords a very delightful and instructive amusement for the leisure hours of those who, retiring occasionally from the gaieties of fashionable life, seek pleasure in the quiet contemplation of some of the smaller, but not less wonderful operations of creative wisdom. and, although the study of shells would be more complete, and rank higher in the scale of philosophical pursuits, were it always accompanied by that of the animal inhabiting them, it nevertheless presents means of intellectual gratification, to many who cannot follow it beyond the cabinet and the boudoir. these may examine with admiration and mental improvement, the beautiful colouring and architecture of these wonders of the deep, they may exercise their taste and judgment in the selection and arrangement of specimens, and their discrimination in detecting and appreciating the distinctions upon which the arrangement is founded. it is but little that can be known of the subject without forming a collection of greater or less extent; for, as it would be uninstructive merely to delight the eye with the bright colours and elegant form of shells, without possessing correct information respecting them, so it would be insipid and useless to learn technicalities without being acquainted by personal observation with the subjects to which they are applied. the first endeavour should, therefore, be to obtain a few shells as examples of the larger divisions, and, when these are understood, to proceed with the smaller groups, until a collection be formed to represent as many generic forms as possible. it may be as well here to advise those who are forming a collection to be very particular in every practicable instance to have the shells properly named at the time of purchasing; as it will save much trouble, and materially assist in the attainment of the desired object. to this end, recourse should be had to those naturalist tradesmen, who unite the attainment and diffusion of real scientific knowledge with their commercial pursuits. supposing, however, that the person who desires to learn the science, possesses a small parcel of unarranged and unnamed shells, without any previous acquaintance with the subject, the following introductory explanations, are drawn up with the view of enabling him, without further assistance, to obtain a general insight into its principles, equal to that of those who have studied it long and laboriously. to effect this, he must read them, carefully comparing the descriptions with the figures referred to, and with the specimens which he may have at command. after describing the nature of the science and defining its objects, we shall proceed to explain the structure of those objects, and the manner of their growth. we shall then enter somewhat minutely into the principles of classification, the distinctions upon which they are founded, and some of the technical terms used to express them. after which we shall pass through the arrangement of lamarck, defining the general divisions adopted under the terms of "_classes_, _orders_, and _families_," as far as they are capable of definition. the subdivision of the latter into _genera_ will only be entered into so far as to enumerate the principal of them, the more minute descriptions being reserved for the alphabetical part of the work. let none be discouraged by the number of generic distinctions proposed and adopted in modern times; for if well defined, they will be found to facilitate rather than encumber the science. the knowledge of species must be the foundation of every system, and the greater their number, the more necessary it becomes to subdivide them; if, for instance, all the species now known were to have been included in the genera of linnæus, a single genus would have contained many hundreds of incongruous species, in which case it would be much more difficult to remember them, than if they were to be divided into a far greater number of genera. every well marked division, however arbitrary its limits, tends to simplify the subject, and to facilitate the researches of the student. nature of the science. conchology is the study of shells, viewed and described as to what they are either in themselves, or in relation to the soft, inarticulate animals which produce them, and of which they form a part. these animals are called mollusca, and perhaps the best general description of them will be found in de blainville's "manuel de malacologie et de conchyliologie." the following is a translation, "animal in pairs, the body and its appendages soft, inarticulate (not jointed), enveloped in a muscular skin, commonly called the mantle, which is extremely variable in form, and has developed either within or upon it a calcareous portion, consisting of one or several pieces, commonly called a shell." the term mollusca was formerly restricted to those soft animals which were destitute of shells, although possessing in other particulars, the characters described above, and it was used in order to distinguish them from the testacea, which were covered or internally supported by calcareous parts. in the system of linnæus, the soft portions are first arranged under the general designation of "vermes mollusca," and described without regard to the presence, absence, or character of the shells; and then the shells are separately characterized under the appellation of "vermes testacea," without any further notice of the animal, than an indication of the genus to which it belongs; thus the animal of cypræa is said to be a limax, and that of tellina a tethys. the nearest approach to correctness, and the most philosophical method of study will be found in the modern system, adopted by lamarck and his followers, of observing these animals as a whole, and arranging them according to the assemblage of characters which they present; of course taking into consideration the existence or non-existence, form and structure of the shell, on the same principle, which, in arranging the vertebrated animals would lead us to study the hair, hoof, nails, claws, &c. as well as the other parts. at the same time, it must be admitted that there are many private collectors of shells who would find it a difficult, if not impossible task to study minutely and successfully the soft parts of the mollusca. ladies, for instance, could not be expected to handle with pleasure and perseverance, these fleshy substances, which in order to be preserved from putrefaction, must be kept in spirits; and yet such persons may, with improvement and advantage to their own minds, enjoy the interesting and scientific amusement of studying and arranging the clean and beautiful natural objects which are so easily preserved, and so exquisitely curious in their structure. let it also be remembered, that if shells had not been rendered commercially valuable, by the zeal and emulation manifested by _mere_ conchologists for the possession of rare specimens, few travelling merchants and sea captains would have thought them worthy of a corner in their cabins. in this case, few specimens being brought to the country, the more philosophical naturalist would have been left without the means of obtaining materials to work upon, or of attracting public attention to his favourite pursuit. on account of these and other considerations, it has been thought advisable that the present undertaking should bear a purely conchological character. the peculiarities of the shells alone being detailed for the assistance of those who collect and study them, while at the same time, in deciding upon their affinities and places, in the arrangement, it will be necessary to take advantage of the conclusion to which those have arrived, who have studied the animal in all its parts. and the conviction must be expressed, that if ever a complete natural system shall be formed it will result from the labours of the last mentioned class of naturalists. definition of a shell. before entering minutely into the description of shells, it will be necessary to distinguish from the true testaceous mollusca two kinds of animals which have formerly been associated with them. of these, the first is the class of crustacea, consisting of crabs, crayfish, &c. these differ from shell-fish, not only in structure and chemical composition, but also in the fact that the animal has jointed limbs, and that the substance of the flesh is inseparable from the hard external covering, which invests each particular joint as with a sheath; whereas the molluscous animal is but partially attached to its shell, from which it possesses the power of partly withdrawing and returning. the second class is that to which the sea-urchin, or echinus, belongs, of which there are many genera and species. the testaceous covering of echini is composed of a number of small pieces, placed edge to edge, forming a more or less globular external covering to the flesh, which is supported in the centre by a number of bones leaning upon each other in a pyramidal form. the _test_ is of a fibrous texture, guarded on the outside with moveable spines, which turn on ball and socket joints. a true shell is composed of one or more calcareous pieces, commonly called valves, each piece formed by a series of layers, applied obliquely upon each other, in such a manner that each new layer begins within, and terminates a little in advance of the one before it. structure and growth. we shall now endeavour to describe the manner in which the growth of each separate valve, or each regularly formed shell, proceeds from the nucleus. before the young animal has left the egg, if it be an _oviparous_ species, or the body of the parent if _viviparous_, the nucleus of the shell is generally formed, and specimens are sometimes preserved in which the young shell is seen within the egg, as in the cut, fig. , ; or adhering to the inner surface of the full-grown shell by the dried mucus of the animal, as seen in fig. . [illustration: . egg of a bulinus. . the same broken, shewing the young shell. . the young of a paludina, as seen in the aperture of the shell.] in both cases, the nucleus is generally of a more horny and transparent composition than the parts subsequently produced. as soon as the animal is hatched, or, in other words, leaves the egg or body of the parent, of course it begins to increase in size, and to require a corresponding enlargement in the shell. to effect this, a small quantity of mucus substance, secreted by the mantle of the animal, is deposited on the edge of the aperture. when this is dry and become sufficiently hard, it is lined by a more calcareous secretion; and these together form a new layer, which is followed by others in succession; each new layer being larger than the one that preceded it until the whole being complete, the full-grown animal is invested with a shell commensurate with its own proportions. thus from the apex or nucleus the formation proceeds, as it were, downwards, taking the shape of the part which secretes it, on which it is in a manner moulded. the nucleus, or first formed portion, may for technical purposes be considered, mathematically, as the apex of a spiral cone. and here it must be observed, that whether the shell consist of one or several pieces, each piece has a separate nucleus, and the process of formation is separately repeated with each. the word cone is used for convenience, and its meaning extended so as to include all those structures which commencing at a point enlarge downwards. [illustration: . imaginary cone. _a._ apex. _b._ base. _l._ lines of growth.] from the apex, the next layer is deposited on its edge, and advancing beyond it necessarily adds to its extent. thus, suppose for the sake of illustration, the part marked _a_ in the diagram, fig. , to represent a nucleus, the cross lines (_l_) will shew the consecutive layers, which enlarge their circle as they add to their numbers. this disposition of shelly matter into layers is marked externally by concentric striæ, or _lines of growth_, while on the inside the edges of the laminæ are consolidated into a kind of enamel. if a perpendicular section of a solid portion of a shell were magnified, it would present, in many instances, an appearance resembling the diagram, fig. ; _a_ may be taken to represent the horny part of the layers which form the outer coating, named "_periostaca_," or "_epidermis_;" the undulating line _b_, is formed by the edges of the calcareous layers, and causes the striæ, or lines of growth, which are often distinguishable on the surface of the shell; the space _c_ is the middle part of those layers, and at _d_ they are consolidated into the enamel which lines the interior. [illustration: . supposed section of a part of a solid shell.] in some species the layers are irregularly grouped together, and their edges overlap each other, so that they are easily separable, and advancing beyond each other, give a leafy appearance to the external surface. this structure is termed _foliaceous_. a very familiar instance of this may be observed in the common oyster. if a specimen of this shell be broken, the substance will be seen to exhibit a degree of looseness, and a magnifying glass will enable the student to trace distinctly the laminæ of which it is composed. the accompanying representation of a magnified section (fig. ) will shew at _a_, the external surface, with the foliations or leaves; at _b_, the parcels of layers which form them; and at _c_, the pearly structure produced by their consolidation, and by the subsequently deposited enamel which covers their external surface. [illustration: . section of an oyster shell enlarged.] classification. the classification of shells, that is, their systematic arrangement into _classes_, _orders_, _families_, _genera_ and _species_, cannot be made to depend entirely upon the characters observable in them, viewed by themselves; for this reason, that many similarly formed shells form the habitations of animals perfectly distinct, and that many molluscous animals are found to agree with each other in every respect but in the form of their testaceous support. there are, however, many important distinctions to be observed in the shells themselves, leading to the establishment of many of those very divisions, which would afterwards be confirmed by an examination of the soft parts. it is necessary to attend, as far as means and opportunity will allow, to _all_ the points of difference, both in the shell and in the animal, in order to form, and in some instances even to appreciate, a generic or larger distinction. it will therefore be our endeavour to explain the general principles upon which those distinctions are formed, and the manner in which they are applied and expressed in detail by scientific writers. number of pieces, or independently formed parts. the first, most simple and obvious division of shells, is that which results from the number of separate pieces composing them. hence the distinction implied by the terms univalve, or consisting of a single piece; bivalve, or composed of two pieces; and multivalve, or composed of more than two. for an example of _univalve_, take a common whelk; for a _bivalve_, take a muscle or a scallop; and for a _multivalve_, the barnacle, or balanus, found adhering to the common oyster. but although this arrangement may appear at first sight perfectly easy and plain, some explanation will be necessary in order to guard the student against understanding the above expressions in their strictest sense, without qualification. thus the univalves are said to consist of a single piece, or spiral cone; but it would be more correct to speak of this piece as forming either the whole or the principal part of the shell: for there is in many instances, a much smaller flattened piece attached to the foot of the animal, which being drawn in when it retires, closes the aperture as with a kind of door, to which in fact the word valve might be very properly applied; it is called however the operculum, and the little horny plate, frequently drawn out by means of a pin from the aperture of a periwinkle, will present a familiar example. [illustration: accessary valves of a pholas.] the same may be said respecting the bivalves; for besides the principal portions or valves of which the shell is composed, there are in many species, one or two smaller separate portions, named "_accessary plates_" by some authors. they are fixed by means of cartilages, on the back of the hinge.--the engraving, fig. , represents the accessary valves of a species of pholas, which was on this account arranged by linnæus with the multivalves. nearly allied to the pholades is a set of shells to which de blainville has given the name "_tubicolæ_," or inhabitants of tubes. in this case, the bivalve shell is connected with a testaceous tube or pipe, to which it is attached either by one or by both valves, or in which it lies attached only by the cartilages of the animal. in the genus aspergillum, the two small valves are soldered into the sides of the tube in such a manner as to constitute a part of it. one of these shells, called the water-spout, might be taken up by a person not aware of its real nature, and regarded as a pipe or tube prettily fringed, and nothing more; but upon a closer examination, he would find the two valves, the points of which are visible from the outside of the tube. habits--_land, fresh-water, or marine shells._ another distinction, leading to important results in classification, is that which is derived from the nature of the element breathed by the mollusc. and although this consideration belongs more especially to the study of the animal itself, yet the habits of the animal materially influence the structure of the shell. the terrestrial or land molluscs live on land, breathe air, and feed on plants and trees.--those who find pleasure in horticultural pursuits will at once call to mind a too familiar example of these molluscs in the common garden snail. the land-shells are all univalves, and constitute a family in the lamarckian system under the name "_colimacea_," or snails, corresponding with the linnean genus helix.--they are generally light in structure and simple in form. the aquatic, or fresh-water molluscs, such as the planorbis, commonly called the fresh-water snail; the unio--known by the name of fresh-water muscle, is found in ponds, ditches and rivers. the _epidermis_ of these is generally of a thick, close-grained character, and they are subject to corrosion near the umbones. there are but few genera of fresh-water shells besides the uniones, among bivalves, and the "melaniana" among univalves. concerning the former it may be observed, that they are all pearly within, and the colour of the thick horny coating embraces all the varieties of brownish and yellowish green. the marine, or _sea-shells_, belong to all the classes and orders, and include by far the greater number of species. they vary in the habits of the animal, and consequently in the situations in which they are found. some are found buried in sand and marine mud, and are named "_arenicolæ_" or inhabitants of sand; others in holes of rocks and other hard substances, then they are named "_petricolæ_,"--some of these latter form the holes in which they live by corroding or eating away the stone. a section of these form the family of "_lithophagidæ_," or stone-eaters, of lamarck. others, again, take up their parasitical abode in the bodies of animals, and feed upon their substance; as for instance, the stylifer, which is found in the vital part of star-fish, and coronula, and tubicinella, found buried in the skin of the whale. locomotion--_attached, unattached._ a much more subordinate source of distinction arises from the freedom or attachment of the shells. some of them float or walk freely in their natural element; others are fixed or attached to foreign bodies. among those which are attached, there is again a difference as to the mode of attachment. some are united to foreign bodies by means of a glutinating substance, secreted by the animal, and joining part of the surface of the shell to that of the stone, coral, or other substance. in this way shells are fixed to each other in groups; this is the case with the spondyli among bivalves, and the serpulæ among univalves. m. de blainville applies the term "_fixæ_" to these shells. others are kept in a particular place by means of a _byssus_ or tendinous fibrous line or bunch of silky hairs, acting as a cable, and allowing the mollusc to ride as it were at anchor. this tendon is connected with some part of the animal from which it passes through an opening or hiatus in the shell, as in the terebratula and the mytilus. [illustration] in the former, represented by the cut, fig. , the tendon passes through a perforation in the upper valve; and in the latter, mytilus, fig. , the byssus passes out between the valves. before proceeding to explain the characters of the different groups, according to the modern system of classification, it may be desirable to explain the terms by which the different parts and characters are described, and to shew the manner in which the shells are measured. for this purpose we shall treat of the general divisions separately. we begin with univalve shells. in considering univalves merely with reference to their mathematical construction, the first point demanding our attention is, whether they are symmetrical or non-symmetrical, or, in other words, whether a straight line drawn through the shell would divide it into two equal parts. the greater part of univalves are non-symmetrical, being rolled obliquely on the axis; but many are symmetrical, being rolled horizontally on the axis. the nautilus presents an illustration of the latter; the snail is a familiar example of the former. _symmetrical univalves._ [illustration] in describing these it will be well to commence with the most simple form, such as the patella,--taking a conical species as an example. in this it will be observed that there is no winding or curvature, but a simple depressed cone, and that the line _a_, _p_, divides it into two equal parts. the _anterior_, _a_, (_cut_, fig. ) is known by the interruption of the muscular impression which surrounds the central disc (_d._) this interruption of the muscular impression is in the place where the head of the animal lies in the shell. the impression itself is caused by the fibrous muscle which attaches the animal to the shell. the apex (_a_) in patella, generally leans towards the anterior (_a_) part of the shell, and away from the posterior (_p_); and this circumstance has caused some mistakes, because in emarginula the apex leans towards the posterior; and students, instead of examining the muscular impression, which is the only criterion, have only noticed the direction in which the apex turned, and concluded that to be the anterior, towards which it inclined. the lines or ribs running from the base to the apex of the shell, in the direction _r_, are called _radiating_ lines; and those which encircle the cone in the direction _c c_, from front to back, are very properly described as _concentric_. the _length_ is measured from front to back in the line _e_; the breadth, from side to side, in the line _b_; and the depth from the apex to the base. let it be observed that patelliform, or limpet-shaped shells are not all symmetrical; umbrella, siphonaria, ancylus, &c. will form exceptions, of which we have yet to speak. and the learner may also be reminded that the limpets themselves are not _all_ regular in their form: for as they adhere to rocks and other rough surfaces, and are so little locomotive, in many instances they partake of the inequalities of the surface, and conform to its irregularities. this adherence is not effected by any agglutinating power in the animal, nor by any tendinous process like that described above; but simply by means of the foot of the animal acting as a sucker. the next variation in symmetrical univalves is to be observed in the tubular, curved form, the example of which will be the dentalium, fig. . [illustration: dentalium elephantinum.] this has an opening at the anterior termination _a_, called the aperture. the opening at the posterior end (_p_) is named a fissure, or perforation. the ribs running along the sides of the shell are _longitudinal_, or radiating. and the lines round the circumference are _lines of growth_, or _concentric_--each one having in succession, at earlier stages of growth, formed the aperture. they are described as concentric, or transverse. _symmetrical convolute univalves._ the nautilus, the spirula, the scaphite, and the ammonite are the leading types of this form; but when we use the term symmetrical, in reference to these, the word must not be understood in its strictest sense, for no shell is _perfectly_ symmetrical: but it means that there is no perceptible difference in the proportion of the two sides; as in the human body, the right side is larger and more powerful than the left, yet to a degree so small that it gives no apparent bias to the figure. chambered shells. many of the shells now under consideration are chambered, that is, the internal cavity is divided into separate compartments by plates reaching across it, named _septa_; and the only connection between the chambers is formed by the small pipes passing through them, to which the name of siphon is attached. _septa._ the septa are _simple_ in some species, as in the nautilus, fig. . in others they are _undulated_, having waved edges, as in some species of ammonites; in others they are _angulated_, as in goniatites, fig. in the plates; and in the greater number of instances, among the ammonites, they are _arborescent_, or branched. [illustration: . section of nautilus.-- . undulating septa.-- . arborescent septa.] in the above section of a nautilus, fig. , diminished in size, showing the whorls and chambers (_c_), it will be seen that the edges of the septa (_s_) are formed in one simple curve. in fig. , the upper part of an ammonite, the undulating line will be seen; and in fig. a specimen is given of the arborescent septa. _siphon._ the siphon is _dorsal_ when placed near the outside of the whorls; _central_ when near the middle; and _ventral_ when near the inside of the whorl, or that part which leans against the last volution. when it passes uninterruptedly from one chamber to another, it is described as _continuous_, as in the case of spirula; when, on the other hand, it only passes through the septum a little distance, and opens into the chamber, as in nautilus, it is _discontinuous_. _whorls of symmetrical univalves._ they are _disunited_ when they do not touch each other, as in the case of spirula (fig. in the plates); but in the contrary case they are said to be _contiguous_. in some species of nautilus the whorls overwrap each other in such a manner that the early whorls are entirely covered by the last, the edges of which reach to the centre of the disk: the spire is then said to be _hidden_; as in the nautilus pompilius. in nautilus umbilicatus the spire is nearly hidden, the whorls not quite covering each other; but in the greater number of the ammonites, the largest part of the preceding whorls is seen. to express the degree in which the whorls overwrap each other, has caused much difficulty in concise descriptions. perhaps it would be well to apply the term _spiral disc_ to so much of the shell as is seen besides the last whorl, and to describe it as large or small in diameter, compared with the whole: or to say that the whorls of the spire are half, or one-third, or one-fourth covered, as the case may be. _aperture of symmetrical univalves._ in ammonites blagdeni and some others the aperture is of an oblong square; it is then said to be _sub-quadrated_; in nautilus triangularis it is _angulated_; in ammonites greenoughi it is of an interrupted oval shape, described as _elliptical_. in the greater number of orthocerata, it is rounded or _circular_. the entrance of the last whorl into the aperture of some rounded species of nautilus causes it to take a _semi-lunar_ form; if rounded at the sides it is said to be reniform or kidney-shaped; if pointed at the sides it is _semi-lunar_; and in some species of ammonites, it is five-sided or _quinque-lateral_. _measurement of symmetrical conical univalves._ [illustration] the _width_ is measured across the aperture, which is the widest part of the shell. the _length_ (_l_) from the dorsal part (_d_) of the aperture to the dorsal part of the _whorl_ (_d_) on the opposite part of the shell. the _ventral_ part of the whorls is that nearest to the axis, and the _dorsal_ that which forms the outline of the figure. non-symmetrical univalves. these are _conical_, _irregular_, _spiral_, or _convolute_. the _conical_ form is when there is no enrolment of the apex. although the patellæ were described as symmetrical, there are several species of patelliform shells which are not symmetrical. in umbrella, for instance, the apex is oblique, the shells being placed obliquely on the animal. in the genus _siphonaria_, there is a groove on one side, where the brachia or gills of the animal rest. in the genus ancylus, it will be observed that the apex bends on one side, and the animal is like the limnæa, which has a spiral shell. the cup and saucer limpets, or calyptrædæ, present a group which requires to be described, differently from the symmetrical or true limpets. their structure is very curious, and they vary considerably among themselves, some of them being simply conical, others nearly flat, or discoidal, and others more or less spiral. but their principal peculiarity consists in their having a small internal process or plate variously shaped, commonly named their _septum_. _septa of limpets._ the septa of limpets assume a variety of forms, the principal of which will be seen in the accompanying engravings. [illustration] the form from which the group derives its generic appellation is that of the cup-shaped or _cyathiform_ species (fig. ). in the crepidulæ, or slipper-limpets, the septum is flat, reaching across the opening, like the deck of a vessel; it is then described as _transverse_ (fig. ). in calyptræa equestris, it has two prominent points, and is described as _bi-furcated_ (fig. ). in another species, it is a three-sided plate rather spiral at the apex (fig. ). _measurement of cup and saucer limpets._ [illustration] the line marked _a_, _p_, _ll_ indicates the direction in which the shell is to be measured for _length_. _a_ indicates the _anterior_, _p_ the _posterior_. the line _d_ (fig. ), from the apex to the base, is the _depth_. the line _b_ (fig. ), is in the direction of the breadth. _irregular non-symmetrical univalves._ serpuliform shells are irregularly twisted (_tortuous_) hollow tubes, which were formerly considered to have been secreted by a kind of worm, but now known to be the shells of true molluscs, of a kind not very widely differing from those which have regularly spiral shells. the greater part of these are attached to foreign bodies, or to each other in groups. some are attached by the whole length of the shell, they are then said to be _decumbent_. some of these are coiled round like the spirorbis, the little white shell seen on the carapace of the lobster or on leaves of sea-weeds; they are then said to be discoidal; others again, such as the _vermetus_, approach more nearly to the spiral form. the deviation from the regular spire only taking place after the few first volutions. spiral non-symmetrical univalves. as these constitute the largest class, it will be necessary to dwell upon them in detail. first as to _measurement_. [illustration] the length is measured from the apex, to that part of the aperture _a_ (fig. ), at the greatest distance from it. the _breadth_ is in the opposite direction. the _anterior_, or front part of the aperture, is marked _a_, where the head of the animal protrudes. _spire of non-symmetrical univalves._ [illustration: fig. , _obtuse_; , _acute_; , , _decollated_; , _concave_; , _papillary_; , _mammellated_; , _discoidal_.] in counting the whorls of which the spire consists, we commence at the apex, and reckon downwards to the last, or body whorl. the spire is described as being long or short in relation to the aperture: in which case, all that is above the aperture is measured with the spire. its apex requires particular notice, as the character of the whole shell frequently depends upon the particulars observable in this part. it is sometimes _obtuse_, or blunt; sometimes _acute_, or sharp. in the cones it is frequently flat, and in planorbis it is concave. it is sometimes of a different structure from the rest of the shell, retaining the horny and transparent appearance which characterized it when the animal was first hatched. the tritons present an instance of this, although it is not always observable, owing to the tenderness of the substances which causes it to break or fall away in many specimens. a very remarkable instance also occurs in bulinus decollatus (cut, fig. , ), so named, because the apex, to the depth of several whorls, falls off, and the shell is _decollated_. in this, and many more instances, among pupæform land shells, the occurrence of this circumstance seems to be by no means rare or accidental, a provision having been made for filling up the opening by a septum. a _papillary apex_ is one which is swelled at the extremity into a little rounded nob, or nipple; and a _mammellated_ apex is one which is rounded out more fully into the shape of a teat. _whorls._ the spire is described as consisting of _numerous_ or _few_ whorls, and sometimes the number of them is particularly stated. a whorl consists of one turn of the spiral cone. the whorls are described as _flattened_, when the sides are not bulged out so as to cause the outline of the spire to deviate considerably from straightness: when the contrary is the case, the whorls are said to be _ventricose_, and either _rounded_ or _angulated_. the degree of rapidity with which the whorls become enlarged presents an important source of distinction. the _suture_, or seam, which separates one whorl from another is also noticed as being _distinct_ or otherwise; _canaliculated_, or grooved; or covered by an enamel, which in some instances is swelled into a ridge or _tumid_. [illustration: fig. , _few_; , _numerous_; , _rounded_, _ventricose_; , _angular_, _ventricose_; , _flattened_.] _suture._ [illustration: fig. , _canaliculated_; , _enamelled_.] _varices._ varices are caused by periodical rests or stoppages in the growth of the shell, when the edge of the aperture thickens, and renders the shell as complete as when full grown. again, after an interval, another check takes place, and another thickened edge is formed, and so on in succession, until the animal arrives at maturity, and the shell is full-grown. the thickened edges successively forming the aperture, remain visible on the outside, through all the subsequent stages. when these rests take place at frequent periods, the varices will of course be numerous as in harpa and scalaria. they occur at regular or irregular distances, varying in shape and other characters. when the varices occur at regular intervals, and form a connected ridge from whorl to whorl up the spire, they are said to be _continuous_, as in ranella; when on the contrary, the varix on one whorl does not come in contact with that on the other, they are described as _discontinuous_. in order to distinguish a regular varix from a mere external ridge, it will be sufficient to notice whether its edge overlaps the external surface, and whether it resembles the open edge of the aperture, which true varices do. [illustration: fig. , _numerous_; , _few, continuous_; , _few, discontinuous_.] _aperture._ the aperture or opening of the spiral tube, was formerly described as the mouth; a term calculated to convey an erroneous impression, when applied to a part of the shell which has no correspondence with the mouth of the animal. the word _aperture_ is used by modern writers in a general sense, including the cavity, its edge, and the canals. the cavity itself is distinguished in various shells as to its shape, which depends much upon the degree of modification produced by the last whorl. in some cases, as in cyclostoma, where the aperture stands apart from the last whorl, the shape is round, or nearly so. the scalaria presents a good example of this. in others, where the inner edge or lip, wrapping over the body whorl is nearly straight, the aperture is _semi-lunar_, or half-moon shaped: this is remarkable in the "_neritacea_" of lamarck, named, on that account, "_hemi-cyclostomata_" by de blainville. in a great number of instances, the lower part of the body whorl enters obliquely into the upper part of the aperture, the result being a _pyriform_, or pear-shaped opening. the aperture is described as _long_ when it is largest in the direction of the axis, and _wide_, in the contrary case. the _anterior_ is the part at the greatest distance from the apex, and the body whorl; the _posterior_, the part nearest to the apex. thus some apertures are described as _posteriorly contracted_ and _anteriorly widened_, or the reverse. a _linear_ aperture is one contracted in its whole length, as in cypræa. when the whorls are angulated, a _trigonal_ aperture is the result, as in many species of trochus. some are _transversely oval_, that is in an opposite direction to the axis, and others _longitudinally oval_. when the whorls are formed with two outer angles, a somewhat quadrated aperture is formed. there are other variations too numerous to mention. _apertures._ [illustration: fig. , helicina, _semilunar_; , pirena, _pyriform_; , cypræa, _linear_; , trochus, _trigonal_; , cyclostoma, _rounded_; , chilina, _posteriorly contracted_; , stomatia, _transversely oval_; , murex, _longitudinally oval_.] the entire edge of the aperture described generally, is named the peritrême, but this term can only be conveniently applied in cases where, in some at least of its characters, it is the same all round, so that one descriptive term is applicable to the whole. as, however, this is of rare occurrence, it is found convenient in descriptions to separate the rim from the outer lip. in a great number of instances, this is done naturally, by a canal, or notch at the anterior or lower extremity, and by the posterior union of that part which overlays the body whorl with the other portion. at these two points the outer and inner lips separate from each other: we therefore describe the _canals of the aperture._ when there is neither notch nor canal, anteriorly or posteriorly, interrupting the edge of the aperture, it is described as entire. when there is a notch or sinus at the anterior extremity, it is said to be _emarginated_. when the edge of this notch is expanded, and drawn out in the form of a beak, it is said to be _canaliferous_, or to have a _canal_. when, in addition to this, the lips are thickened and contracted posteriorly near their junction, and drawn out so as to form a groove, it is said to be _bi-canaliculated_, or to have two canals. the _anterior canal_ is said to be long or short, according to the proportion which it may bear to the rest of the shell. thus the canal of ranella ranina (fig. in the plates), may be described as _short_; while that of murex haustellum, (fig. , pl.) is _long_. when it is wide near the aperture, and becomes gradually contracted towards its termination, it is said to be _tapering_, as in pyrula (fig. , pl.); when the termination is sudden, it is described as _truncated_. if, on placing the shell upon a plane, with the aperture downwards, the canal is seen to rise upwards, it is _recurved_. in buccinum and nassa it is turned suddenly over the back, and forms a short, curved elevation; it is then described as _recurved_ and _varicose_. if the edges meet, so as to form a tube, it is said to be closed, as in some species of murex and typhis. the posterior canal is, in some cases, _free_, or standing out from the spire, as in some species of ranellæ; while in others it is _decumbent_, running up the sides of the spire, as in rostellaria (fig. , pl.). _canals._ [illustration: fig. , fasciolaria, _truncated_; , nassa, _recurved_, _varicose_; , cerithium, _recurved_; , typhis, _closed_.] _lips, or edges of the aperture._ the part of the edge of the aperture next to the body whorl is named the _inner_, or _columellar_ lip. posteriorly it commences at the point of union with the outer lip, where that touches the body whorl, the junction being generally marked by an angle, and sometimes by a canal. anteriorly it terminates where there is generally seen a notch or canal, or sudden angle, from which the outer lip proceeds. the part which setting out from the body whorl, and proceeds outwards at a distance from the axis, till it reaches the anterior canal or notch (or its place in case of absence) is named the _outer lip_. in many cases the edges are united in such a manner, that it is difficult to distinguish where the inner lip terminates, and the outer lip commences: when this is the case, it is usual to describe the margin or peritrême, as a whole, without distinguishing the parts. the _outer_ lip, sometimes called the right lip, or _labrum_ of continental writers, is sometimes acute, not being of thicker substance than the remainder of the shell. in other cases it is _obtuse_, or thickened and rounded at the edge. when thickened and turned backwards it is described as _reflected_; when, on the other hand, it is turned inwards towards the axis, as in the cyprædæ, it is _inflected_, or involute. when it is _toothed_, a distinction must be observed as to whether the dentations are external or internal. if the teeth are small and numerous, it is _denticulated_; if larger, it is _dentated_; when expanded into a kind of wing, as in some species of strombus and rostellaria, it is described as _alated_; and a family in lamarck's system is named "alatæ," from this very circumstance. in some of those which are expanded, the expansion is divided into separate, attenuated portions, they are then said to be digitated. _outer lips._ [illustration: fig. , helix, _reflected_; , cypræa, _involute_, _denticulated_; , sera, _alated_; , murex, _digitated_; , rostellaria, _dentated_.] the _inner_ lip, sometimes named the _columellar_ lip, or "_labium_," is subject to similar variations as to thickness, dentition, &c. that portion of it which lies upon the body-whorl is frequently distinguished from that which intervenes between it and the notch or canal. de blainville, restricting the term _lip_ "bord gauche" to the former portion, applies the term "columella" to the latter; and in some instances this may be the more convenient method of describing the part in question. the columellar lip is sometimes _detached_ entirely from the body of the shell, as in murex haustellum; in others it is _decumbent_, or lying over the last whorl, although quite distinct, and in some cases, _thickened_, _callous_, or _tumid_. at the lower or anterior part, sometimes called the _columella_, there are in many instances flattened, laminated folds; these are particularly conspicuous in the genera cymba and melo, where, being obliquely spiral and laminar, they are extremely elegant, presenting to the eye graduated repetitions of the line of beauty. in other cases, as in the turbinellæ, they are more horizontal and thickened. in some cases the columella is swelled into a varicose mass; as in oliva, ancillaria, &c.; it is then described as _tumid_ or varicose. it is sometimes _tortuous_, and sometimes straight, and is susceptible of many variations, too minute and particular to be described in this part of the work. columellar lips. [illustration: fig. , melo, _obliquely plaited_; , turbinellus, _horizontally plaited_; , ancillaria, _varicose_, _tortuous_; , natica, _straight_.] operculum. the aperture of many species of shells remains constantly open; but in a great number of species it is occasionally closed, whenever the animal is retracted within the shell, by a calcareous or horny piece called the operculum. this must be distinguished in the first instance from another kind of calcareous covering, which in some univalve shells serves to close the aperture during a certain portion of the year. this piece, named the _epiphragm_, although hardened and shelly in appearance, is no real part of the animal or of the shell; being only a secretion temporarily hardened, for the purpose of defending the animal from external influences during the _hibernating_ or _torpid_ season, to be dissolved when that season is at an end. on examining this piece, it will be observed that it is not formed in regular layers like the rest of the shell; while the true operculum is of a regularly laminated structure, having a nucleus and receiving obliquely deposited additions, either in a lateral spiral or concentric direction. it is attached to the posterior part of the foot on the upper surface; and when the animal retires within its shell, that part of the foot enters last, drawing the operculum after it, and thus closing the aperture. the opercula of various shells differ in the first place as to their chemical composition. they are _calcareous_ when formed principally of calcareous matter, like the rest of the shell, as in neritina, nerita, and some others. they are _corneo-calcareous_, when upon an internal lamina of horny consistency there is a thickened layer of shelly matter. this is the case with shells of the genus turbo and phasianella, which are on this account distinguished from those of the genus trochus; the opercula of the latter being horny or _corneus_. the size of the operculum is distinguished by comparison with the rest of the shell; thus, those of strombus, cassis, &c. are small; while those of cyclostoma and others are large, filling up the cavity at its outer edge. the direction in which the successive layers are deposited, forms another ground of distinction. the disc is formed in some instances of a series of whorls, the apex or nucleus being more or less central; if these whorls are numerous, the operculum is described as _multispiral_, as in shells of the genus trochus; if few, as in cyclostoma, it is _paucispiral_. in some instances the flattened spire consists of but one whorl, it is then _unispiral_; and when scarcely one turn is completed, it is described as _subspiral_. when the layers are applied upon each other in such a manner that the nucleus is central, and the edges of the subsequent layers are extended beyond each other all around, so as to form rims, the operculum is described as _concentric_; if the nucleus is lateral, or at one side without being spiral, it is _lammellated_; and when it forms a terminal point, enlarging in the form of a finger-nail or claw, it is _unguiculated_. in the operculum of a neritina, there is a lateral process, by means of which it is locked into the columella, the term _articulated_ is then applied. in that of navicella, there is also a process which appears to radiate from the nucleus, it has therefore been described as a _radiated_ operculum. _opercula of spiral univalves._ [illustration: fig. , _multispiral_; , _paucispiral_; , _concentric_; , _articulated_; , _radiated_; , _lammellated_; , _unguiculated_.] bivalve shells. bivalve shells, named conchacea by lamarck, are those which consist of two principal portions united to and folded upon each other by means of a hinge. the pieces united compose the shell, while each piece separately is called a valve. considering the bivalve shell as a whole, it will be necessary, in the first instance, to describe the position in which it is to be observed, in order to give the student a clearly defined notion of what is intended, when terms expressive of height, depth, length, breadth, &c. are used, as well as when the anterior and posterior extremities are spoken of. for this purpose, we must suppose the animal to be living and creeping along the bed of the sea by means of its foot; where this foot protrudes, will be the _ventral margin_, and the opposite part the _dorsal margin_ of the shell. there will then be a valve on each side; and if we further suppose the animal to be walking forward with its back to the observer, the _right_ and _left_ valves will correspond with his right and left sides. _measurements._ [illustration] the _length_ will be measured from _anterior_ (_a_) to _posterior_ (_p_), and the lines of growth running in the same direction will consequently be _longitudinal_ or _concentric_; _transverse_ of some authors. the height will be from the umbones (_u_), to the _ventral margin_, and lines or bands in that direction are termed _radiating_; longitudinal, according to some authors. the points from which the growth of the shell commences, are called the _umbones_; these usually turn towards the anterior part of the shell: if this circumstance fails to point out the anterior, it may in many cases be distinguished by the muscular impressions of the mantle. if this has a sinus or winding, it is always near the posterior muscular impression; and in all cases where there is an external ligament, it is on the posterior side. there is sometimes an impression near the front of the umbones, which forms a semicircle on each valve; the space within this semicircle is called the _lunule_ (wood-cut, fig. and , _l. l. l._); a corresponding depression, when it exists on the posterior margin near the umbones, is named the escutcheon. _hinge._ [illustration: fig. , _l t_, lateral teeth; _c t_, cardinal teeth; _c_, cartilage under the ligament; _l_, ligament; _f_, fulcrum of the ligament.] the _hinge_ of the shell is on the _dorsal_ margin, and is composed of the various apparatus by which the two valves act upon each other in opening and shutting. it consists of a _ligament_, which is placed on the dorsal margin, just at the back of the umbones, and unites the two valves together; the _cartilage_ or thick gristly elastic substance, sometimes found close to the _ligament_, to which it then forms an inner coating, and sometimes received into a pit within the shell. it serves the purpose of keeping the shell open when not forcibly closed by the adductor muscles. an inner layer of shelly matter upon which are placed teeth, and pits to receive them on the two valves reciprocally. each of these it will be necessary to treat of more at large; observing, at the same time, that in some species of bivalves these parts may be wholly or partially wanting. thus we meet with some shells, such as the muscle, without teeth; and there is the group containing pholas, &c. the hinge of which is destitute of teeth and ligament, the two valves being kept together by loose cartilages, and by the contracted space in which they are confined. _ligament and ligamentary cartilage of the hinge._ these two distinct substances have been described by many writers as though, composing the same mass, they were of one substance; but the difference may very easily be explained. the _true ligament_ is external, being fixed on the edge of one valve behind the umbones, and passing over in an arch to the corresponding edge of the other, very correctly retaining the name of _ligament_, because it serves the purpose of binding the two together. the thick, elastic substance, which mr. gray names the _cartilage_, is sometimes found in connexion with the ligament, so as to form one mass with it, although it is always separable and placed within it: it is sometimes placed quite within the shell, and separated from the ligament, in a pit or hollow formed for its reception in the hinge lamina, near the centre. it is found in both valves, and being elastic, the portion in one valve presses against that in the other, so as to keep the valves apart, unless voluntarily closed by the adductor muscles of the animal. the ligament is sometimes spread over an external area, as in arca, while the cartilage is placed in several grooves of the same area, beneath the outer covering. _hinge lamina, teeth and fulcrum of the ligament._ in a great variety of cases, there is a thickening of the substance of the shell within, under the dorsal margin; this is named the hinge lamina. it is sometimes merely callous; but in many cases it has raised _teeth_ in both valves, those in one valve entering into corresponding cavities in the other. those which are placed immediately below the umbones, and seem to take their rise from beneath them, are called _cardinal teeth_; those at a distance from the umbones, which are seen to lie along the upper margin of the shell are named _lateral teeth_. when the cardinal teeth terminate in a double point, which is not unfrequently the case, they are said to be _bifid_. the lateral teeth, in various species, are distinguished as terminating _near_ to, or at a _distance_ from the umbones. in the nuculæ and arcæ there is a row of teeth placed across the hinge lamina. in which case, the lateral cannot be distinguished from the cardinal teeth. _muscular impression._ [illustration: fig. . _a, anterior; p, posterior; m i, muscular impressions._] lamarck divides the bivalve shells into two general orders; the first is named "dimyaria," having two adductor muscles; and the second, "monomyaria," having but one. these adductor muscles are used for the purpose of drawing the valves together, being composed of contractile fibrous gristle, fastened firmly to the inner surface of each valve. the place where they are thus fixed may be seen when the animal is removed, by depressed areas, which are generally pretty well defined, and are named _muscular impressions_. where there is but one adductor muscle, there will be but one of these impressions near the centre of each valve, but in the dimyaria, where there are two, the impressions are seen, one on the anterior, and one on the posterior of each valve, just below the _hinge_ lamina. they are sometimes _complex_, that is composed of several portions in a group; but in general, they are simple and well defined. they are also described as large or small, in proportion to the size of the shell; regular or irregular in form. the animal is attached to the inner surface by the fibrous portions of the mantle, which creates a linear impression or _cicatrix_, commonly described as the _palleal impression_, or muscular impression of the mantle. it runs near the ventral margin from one muscular impression to the other, sometimes in a smooth _continuous_ line or band, and sometimes in an interrupted series of small impressions. near the point of union with the posterior muscular impression, there is sometimes a more or less considerable winding inwards towards the centre of the shell, and back again towards the point of union. this is named the _sinus_, and is distinguished as being _angular_ or _rounded_, large or small, according to the species. when it enters towards the centre of the shell in a tongue-shaped outline it is said to be _ligulate_. where it exists it affords a certain index to the posterior side of the shell; as it is the region through which the excretory tubes pass. _umbones._ these are the prominent points of the dorsal edge, where the growth of the shell commenced, and are called beaks, by some english writers. in some instances they are close to each other; in others they are rendered distant from each other by the intervention of areas in the hinge, as in spondyli, &c. in pectunculus they are _straight_; in venus _curved_ towards the anterior margin; in isocardia, _spiral_; in chama, _decumbent_; in diceras, _free_. in shells subject to external corrosion, the process commences at the umbones. [illustration: fig. , _distant_; , _straight_; , _curved_; , _spiral_; , _decumbent_; , _free_; , _close_.] general character of bivalves. when the _breadth_ is spoken of, the distance between the most convex parts of both valves, when closed, is intended; but when an expression implying _thickness_ is used, it refers to the substance of each valve: it is important to bear this in mind, as many persons have been misled by descriptions in which the distinction has not been attended to. glycimeris (fig. in the plates) is a _thick_ shell, but anatina (fig. in the plates) is a _broad_ one. _regularity._ a great number of bivalves are extremely regular in their form. these are generally locomotive, and consequently free from those obstructions in growth occurring to stationary shells, which being confined in a particular position, or to a particular spot, modify their shape according to the substance with which they come in contact, and thus become irregular. this is generally the case with shells which are attached to submarine substances, such as spondyli, oysters, &c.; and the degree of irregularity will depend upon the extent of surface involved in the attachment. in the case of fixed shells, the attached valve is usually termed the under valve, and the other which moves freely upon the hinge, is termed the upper valve. _form and proportions._ bivalves are said to be _equivalve_ when the two valves correspond in extent, breadth, and thickness; and of course _inequivalve_ in the contrary case. they are _equilateral_ when a line drawn from the umbones to the ventral margin would divide the shell into two nearly equal parts; and of course _inequilateral_ in the opposite case, which occurs in the great majority of instances. a bivalve is said to be _compressed_, when the distance is small from the most prominent part of one valve to that of the other. it is _cylindrical_ when lengthened, and more or less rounded in its breadth, as in lithodomus (fig. in the plates). it is _cordiform_ when the shape presents a resemblance to an imaginary heart, as in cardium cardissa (fig. in the plates), and in the isocardia (fig. in the plates). it is _linguiform_ when it resembles a tongue in shape, as in vulsella (fig. in the plates); _rostrated_ when it protrudes at either extremity, and terminates in a kind of point, as in sanguinolaria diphos (fig. in the plates); _truncated_ when it ends in a square or angle, as if cut off; an example of which may be seen in solen (fig. in the plates). other bivalves are distinguished as being _auriculated_, having processes flattened and expanded on either side of the umbones, as in pecten (cut, fig. ). when there is one of these on each side of the umbones, it is _bi-auriculated_; when only on one side, it is _uni-auriculated_. when the expansion is very broad, as in unio alatus (fig. in the plates), and in the hammer oyster (cut, fig. ), the term _alated_ is used. [illustration: fig. , _auriculated_; , _auriculated_, _alated_.] with regard to these alated species of _uniones_, it is necessary to observe that they are also "_adnate_," as it is termed; the two valves being joined to each other by the dorsal edge of the expanded parts, and united so completely in substance with each other, that they cannot be separated without being broken. many other terms are used to express difference in bivalves, but being generally applicable to univalves and multivalves, as well as to them, they will be found explained at large in the alphabetical part of the work. multivalve shells. these are of three different kinds; first, the "_dorsal_," as they are termed by linnæus, because they form a ridge in the back of the animal. they are composed of eight pieces, or separate valves, placed in a longitudinal series, being joined to each other by inserted lamina, and named _articulata_ by de blainville, on that account. the genus chiton is the only example of this kind of multivalves. [illustration: fig. , , chiton. _a_, anterior; _p_, posterior; _d_, dorsal ridge; _l l_, lateral areas of the valves; _c c_, central areas; _i i_, inserted lamina; _m_, margin.] the second kind, m. de blainville terms the _lateral_ bivalves, the pieces being placed in pairs on each side of the animal; these compose the "pedunculated cirripedes." [illustration: fig. , anatina.] they differ considerably in the number and arrangement of the valves; the small ones, which are found near the peduncle in some species, are sometimes termed accessary valves; those which form the edge through which the bunch of cilia protrude, are termed _ventral_, and those on the opposite side _dorsal_. the extremity joining the peduncle is the basal, or anterior; and the upper extremity is the apsiral, or posterior. the peduncle is the medium of attachment to submarine substances, to which this well known tribe of shells adhere. the third kind are termed _coronular_ by de blainville, and compose the order sessile cirripedes of lamarck; they consist of a number of valves placed against each other side by side in a circle, supported on a plate, or tube, or cup, and closed by an operculum composed of two or more valves. the _basal support_ is sometimes thick and flat, sometimes forming an elongated tube, and sometimes hollowed out into a cup. in other species it is altogether wanting. the operculum always consists of more than one piece, generally of two pairs: they are either articulated to each other by serrated edges, and placed against each other conically, as in balanus, or they lie flat in two pairs against each other. through the ventral pair the _cirrhi_ protrude. the _parietal_ valves, composing the principal part of the shell, vary in number, form and position. the _anterior_ valves are placed on the same side with the cirrhi; the _posterior_, those on the opposite side; and those which remain between on each side are the lateral valves. in many cases, particularly in balanus, each valve is separated into the _prominent_ and _depressed_ areas, and the inserted lamina. in some instances, the parietal portion is formed by a single rounded piece. [illustration] in the accompanying cut ( ), the prominent areas are distinguished by the letters _pr_, and the depressed areas by _r_; the posterior valves of the operculum are marked _p. o._, and the anterior _a. o._ the basal valve (fig. ) belongs to a balanus. fig. is an acasta, the cup-shaped base of which is represented at fig. . in the foregoing explanations we have omitted many of those general terms which, relating to external characters, are applicable to shells in almost every division of the system. it may be as well, however, to enumerate a few of them in this place, although they are explained under their respective letters in the alphabetical part of the work. when bars or ribs, or large striæ are crossed by others radiating from the umbones, shells are said to be _cancellated_, as represented in cut, fig. . when there is a series of nodules or spines on the upper part of the whorls, they are _coronated_, as shewn in cut, fig. . when a series of projecting parts overlay each other, in the manner of tiles, as in the cut, fig. , the word _imbricated_ is applied. when marked by a regular series of ridges, radiating from the apex, they are _pectinated_; the species of chiton, a single valve of which is represented in cut, fig. , has received the specific name of _pectinatus_, in consequence of this character. shells are said to be _plicated_ when characterized by angular bendings or foldings in their surface, as shewn in cut, fig. . a strong instance of this is seen in the ostræa crista-galli. when the margin of any shell has a series of minute notches, resembling the teeth of a saw, it is said to be _serrated_; when covered with raised points or spines it is _aculeated_; and when striated in both directions, it is _decussated_; when covered with a number of raised rounded points, it is _granulated_; and having a series of these points placed in a row, near or upon the edge, it is _denticulated_, as already explained in reference to the outer lips of spiral univalves. when the external surface is rendered uneven by raised knobs, it is said to be _tuberculated_; and if rendered rough and prickly by sharp points it is _muricated_, as in the cut, fig. . the term _reticulated_ is applied to fine raised lines, crossing each other, and resembling fine net-work. [illustration: external surface. fig. , _cancellated_; , _coronated_; , _imbricated_; , _pectinated_; , _plicated_; , _decussated_; , _muricated_; , _foliated_.] by the foregoing general observations and explanations, it is trusted that the reader will be prepared for the following exposition of the general arrangement of lamarck, and the principles upon which it is founded. * * * * * general arrangement according to lamarck. in lamarck's "histoire naturelle des animaux sans vertebres," he divides the invertebrata into classes, the th, th, and th of which include animals possessed of shells properly so called. these are the annelides, the cirripedes, the conchifera, and the mollusca. the class annelides constitutes the th, and is divided into three orders, namely, the "apodes," "antennees," and "sedentaires"; the last of which, _sedentaria_, alone contains testaceous animals. this order includes tubular shells, which, with the exception of dentalium, are irregularly twisted, and attached to each other, or to extraneous substances. the first family _dorsalia_, contains the genus siliquaria (plates, fig. ), known from the serpulæ, by the slit which passes through the whole length of the shell on the upper surface of the tube. the second family, _maldania_, has the genus dentalium (plates, fig. ), a species of which are commonly known by the name of "tooth shells"; these are regularly formed, curved conical tubes, open at both extremities. the third family, _serpulacea_, includes the genera serpula, spirorbis, galeolaria, vermilia, spiroglyphus, and magilus. the only shell that a learner would be likely to place among these incorrectly, according to the system, is the vermetus (plates, fig. ), which being regularly spiral at the apicial extremity, has been placed among the mollusca; to which situation the whole of the shells under consideration have a better title than is generally supposed. it should be mentioned that the serpulacea are provided with opercula. class cirripedes. this class constitutes the tenth of invertebrated animals, and receives its name from the jointed and ciliated branchia which protrude between the opercular valves. they are multivalve shells, and were all included in the single genus lepas in the system of linnæus, and are commonly known by the name "barnacles." lamarck has, however, divided them into two distinct orders. first, the _sessile_ cirripedes or those which being composed of several valves, joined to each other, side by side in a circle, are attached to each other, or to submarine bodies by the basal portion of their own substance, and form a hollow, irregular cone, with the aperture above closed by an operculum consisting of two or more valves. secondly, the _pedunculated cirripedes_, which are composed of valves placed in pairs against each other, so as to form a flattened disc attached by means of a tendinous tube called a peduncle. the first of these orders includes the genera tubicinella, coronula, platylepas, clitia, conia, elmineus, catophragmus, octomeris, balanus, creusia, nobia, savignium, pyrgoma, adna, megatréma. the second contains the genera pentelasmis, scalpellum, smilium, pollicipes, bisnæus, lithotrya, ibla, octolasmis, cineras, otion. conchological writers are not agreed as to the propriety of allowing the above to enter into the present science. class conchifera. the shell of a conchiferous animal is always bivalve, composed of two pieces placed opposite to each other, joined at the dorsal margins by an elastic hinge. all true bivalve shells belong to animals of this class; and the correspondence between the shell and the animal is so true that on examining an empty bivalve shell we can not only determine that its inhabitant belonged to this class, but also decide on the particular order and family in which it should be placed, without seeing the soft parts. the first general division of conchifera is that which results from observing the muscular impressions, or marks made on the inner surface of the valve by the insertion of the adductor muscles. all conchifera are divided into two orders, as follows: first order, _conchifera dimyaria_. having two adductor muscles, and consequently two impressions in each valve. they are separated into the following families: . _tubicolæ_ (plates, fig. to ), having shelly tubes besides the valves. this family contains the genera aspergillum, clavagella, teredina, teredo, xylophaga, fistulana, and gastrochæna. . _pholadaria_ (plates, fig. to ), cylindrical, living in holes in rocks pierced by the animals. lamarck places in this family the genera pholas and gastrochæna, the last of which belongs more properly to the family tubicolæ, as placed above. . _solenacea_ (plates, fig. to ), longitudinally (transversely, lam.) elongated, open at the anterior and posterior extremities. this family contains the genera solen, pholadomya, panopæa, glycimeris (solecurtus) and solenimya. . _myaria_ (plates, fig. to ), ligament internal. a spoon-shaped ligamentary pit in one or both valves. shell generally gaping at one or both extremities. this family includes the genera anatina, mya, anatinella, lyonsia, myochama, cleidotherus. . _mactracea_ (plates, fig. to ), the cartilage placed in a trigonal pit, with a small external ligament. the genera lutraria, mactra, crassatella, erycina, ungulina, amphidesma, and solenimya belong to this family, the last of which ought to have been placed among the solenacea, as above. . _corbulacea_ (plates, fig. , ), inequivalve, with an internal ligament resembling the mactracea, but differing in having one valve deeper than the other, although regular shells. this small family contains only the genera corbula and pandora. . _lithophagidæ_ (plates, fig. to ), irregular, terebrating, living in holes of rocks. the genera are saxicava, petricola, and venerirupis. . _nymphacea_ (plates, fig. to ), ligament external, generally placed upon a prominent fulcrum, which passes from the inside to the outside of the hinge; valves generally gaping at the extremities. this family contains the genera sanguinolaria, psammobia, psammotæa, tellinides, corbis, lucina, donax, capsa, and crassina. . _conchacea_ (plates, fig. to ), regular, having several cardinal teeth and sometimes lateral teeth. the conchacea constitute one of the most beautiful and numerous families of the class; they present equivalve shells, which are always regular, unattached, and in general closed, especially at the sides; they are always more or less inequilateral. they are divided into the _fluviatile_ and _marine conchacea_, the first containing the genera cyclas, cyrena, and galathæa, found in rivers; and the second, cyprina, cytherea, venus, and venericardia. . _cardiacea_ (plates, fig. to ). this family, which resembles the last in some general characters, are also regular and equivalve, and are generally provided with radiating ribs, which are seldom seen in the conchacea. the genera enumerated in this family are cardium, cardita, cypricardia, hiatella, and isocardia. . _arcacea_ (plates, fig. to ). these are known by having a row of numerous small teeth on the cardinal hinge in each valve. the genera included are, cucullæa, arca, pectunculus, nucula. . _trigonacea_ (plates, fig. and ). it is doubtful whether this family should remain distinct. as of the two genera placed in it, the first, trigonia, is thought by some naturalists to have strong affinities with nucula, in the family of arcacea; and the latter, castalia, certainly belongs to the nayades. . _nayades_ (plates, fig. to ). these are fresh-water shells, covered on the outside by a thick horny epidermis, and pearly within. they include the genera unio, hyria, anodon, iridina. . _chamacea_ (plates, fig. to ), inequivalve, irregular, foliaceous, attached; containing the genera diceras, chama, and etheria. second order, _conchifera monomyaria_. having one adductor muscle, and therefore only one impression in each valve. they are separated into the following families:-- . _tridacnacea_ (plates, fig. & ), transverse, equivalve, with an elongated muscular impression, near the centre of the ventral margin; margin undulated at the termination of the radiated large ribs. the genera tridacna and hippopus are included. . _mytilacea_ (plates, fig. to ), generally regular, with the hinge linear, without teeth, occupying the greater part of the dorsal margin. this family includes the genera modiola, mytilus, pinna. . _malleacea_ (plates, fig. to ), shell generally thin, inequivalve, irregular, foliaceous, with the hinge linear. this family contains the genera crenatula, perna, malleus, avicula, meleagrina. . _pectinides_ (plates, fig. to ). the pectinides are generally regular or nearly so, with the shell solid; the greater part of them are auriculated at the dorsal margin, and generally characterized by ribs radiating from the umbones. the genera are pedum, lima, plagiostoma, pecten, plicatula, spondylus, podopsis. . _ostracea_ (plates, fig. to ). the shells of this family are irregular, generally attached and foliaceous. they compose the genera gryphæa, ostræa, vulsella, placuna, anomia. . _rudistes_ (plates to ). this family is composed of a particular association of shells, which appear on one side to be connected with the ostracea; and on the other to approach the brachiopoda. they differ from ostracea in having no hinge or ligament, and only resemble them in their irregularity and foliaceous structure. the following six genera are placed by lamarck in this family:--sphærulites, radiolites, calceola, birostrites, discina, crania. of these, calceola, discina, and crania are shewn to belong to the brachiopoda. . _brachiopoda_ (plates, fig. to ). the shells of this family are inequivalve, equilateral, and attached to marine bodies by a tendon passing through one of the valves. the animals have, near their mouth, two elongated, ciliated arms, which are spirally rolled when at rest. the following genera are enumerated by lamarck, orbicula, terebratula, lingula. mollusca. lamarck applies, or rather restricts, this name to those invertebrated animals, which while they are inarticulate in all their parts, have the head sufficiently advanced at the anterior part of the body to be distinguished; which is not the case with the conchifera. all the shells are univalve, and are divided into six orders, namely, the pteropoda, which have wing-shaped natatory organs or fins, and have _light_, _thin transparent_, _nearly symmetrical_ shells; the gasteropoda, with the foot not distinguishable from the rest of the body, have _patelliform_, _open_, and _scarcely spiral_ shells; the trachelipoda with the foot distinct and attached to the neck of the animal, have _spiral_, _non-symmetrical_ shells. the cephalopoda, with arms covered by suckers surrounding the head of the animal, have generally _symmetrical convolute_ shells. the cephalopoda are divided into _c. polythalamia_, which have the internal cavity divided into chambers by septa, as in the nautilus; and the _c. monothalamia_, which are not so divided, as the argonauta. the order _heteropoda_ contains the genus carinaria alone. order _pteropoda_. this order, containing hyaline, symmetrical, non-spiral shells, as above described, is not divided into families, but contains the following genera, hyalæa, cleodora, limacina, cymbulia; the first of which, although composed of a single piece, resembles a bivalve so nearly, that linnæus actually placed it in his genus anomia. order _gasteropoda_. with the exception of the genus bulla and vitrina, the last of which forms a passage into the next order, the shells contained in this order are _patelliform_, _open_, _and scarcely spiral_. they are divided into the following families:-- . _phyllidiana_ (plates, fig. to ), containing the genera chiton, chitonellus, and patella, the two former of which present the only exception to the statement above made, that all the shells of mollusca were univalve. . _semiphyllidiana_ (plates, fig. and ). of the two genera contained in this family, pleurobranchus is broad, thin, and slightly spiral at the apex, and umbrella is flat, circular, with a central apex. . _calyptracea_ (plates, fig. to ). the patelliform shells of this family, although united by no other general characters, are brought together by the characters of the animals which produce them. the genera are parmophorus, emarginula, siphonaria, fissurella, pileopsis, calyptræa, crepidula, ancylus. . _bulleana_ (plates, fig. to ), contains the genera bulla and bullæa. . _aplysiacea_ (plates, fig. and ). the genera aplysia and dolabella are both expanded, somewhat flattened shells, with the apex placed at one extremity, and slightly spiral. . _limacinea_ (fig. to ). many of the animals (slugs) are without shells; some, as the limax, or common garden slug, have a slightly developed calcareous piece, hidden beneath the mantle, and of others the shells are scarcely spiral. the genera included in this family are, parmacella, limax, testacella, vitrina. order _trachelipoda_. all the remaining spiral non-symmetrical shells are arranged in this order, which is divided into the following families:-- . _colimacea_ (plates, fig. to ). with the exception of the few contained in the family of limacina, which ought not to be separated from this order, the whole of the land-shells are contained in this family, and although it is difficult to notice any one character by which terrestrial shells may be distinguished from others, few at all conversant with the subject are liable to mistake them. there is a general lightness and simplicity of form, which, though not clearly definable, is generally understood. the following distribution of genera by lamarck, is generally acknowledged to require numerous modifications; the genera are helix, carocolla, anostoma, helicina, pupa, clausilia, bulinus, achatina, succinea, auricula, cyclostoma. . _lymneana_ (plates, fig. to ). the shells of this family are found in fresh water, wells, ditches, and ponds. they are of a light horny structure, and simple form. the genera planorbis, physa, and lymnea are placed in this family by lamarck. . _melaniana_ (plates, fig. to ). these are also found in fresh water, principally in rivers; they are thicker than those of the last family; and the greater part of them have elevated spires composed of numerous whorls. this family contains the genera melania, melanopsis, pirena. . _peristomata_ (plates, fig. to ). these are also fresh-water shells, having opercula, and covered by a smooth green, or greenish-brown epidermis. they differ from the last family in having the peritreme entire. the genera are valvata, paludina, and ampullaria. . _neritacea_ (plates, fig. to ). the peculiarity of the shells of this family consists in the inner lip being flattened and rather straight at the inner edge. the genera are navicella, neritina, nerita, natica, and janthina, the last of which forms an exception to the general character, and is placed by de blainville in a family by itself. . _macrostomata_ (plates, fig. to ), so named, on account of the large open aperture which they present in comparison to the spire. the shells of this family, which contains the genera stomatia, stomatella, and haliotis, are pearly within. . _plicacea_ (plates, fig. to ), contains the genera tornatella and pyramidella. . _scalariana_ (plates, fig. to ). the genera vermetus, scalaria and delphinula, seem to have been placed in this family by lamarck, on account of the whorls being distinct from each other. . _turbinacea_ (plates, to ). the shells contained in this family are all more or less globose, or angular, thickened and pearly within. the following genera are included in this division by lamarck, solarium, rotella, trochus, monodonta, turbo, planaxis, phasianella, and turritella. . _canalifera_ (plates, fig. to ). the numerous genera of which this family is formed, namely, cerithium, pleurotoma, turbinella, cancellaria, fasciolaria, fusus, pyrula, ranella, murex, triton, are distinguished by having at the anterior termination of the aperture, a more or less elongated canal. . _alatæ_ (plates, fig. to ). these are known by having the outer lip more or less expanded and generally a posterior canal leaning towards the spire. the genera are rostellaria, strombus, and pteroceras. . _purpurifera_ (plates, fig. to ). in these, the canal, if such it may be called, is extremely short, and turning abruptly backwards, produces a kind of varix at the lower part of the whorl. the genera enumerated in this family are cassidaria, cassis, ricinula, purpura, monoceras, concholepas, harpa, dolium, buccinum, eburna, terebra. . _columellata_ (plates, fig. to ). the shells of this family are emarginated at the anterior extremity of the aperture, and the inner lip is characterized by plates or folds, which, with the exception of those on columbella, are distinct. the genera are mitra, voluta, marginella, volvaria, columbella, the latter of which would be better placed among the purpurifera. . convolutæ (plates, fig. to ). the well-known shells contained in this family are distinguished for the small proportion of the spire, if any, which remains uncovered by the last whorl. they might be well divided into two groups, the first containing the genera ovulum and cypræa, under the name of cypræadæ, which are truly convolute, having the spire entirely hidden; and the second containing the genera oliva. ancillaria, and conus. order _polythalamous, or chambered cephalopoda._ the greater part of the shells belonging to this order are symmetrical, and the internal cavity is divided into separate compartments, by plates called _septa_. it is divided into the following families:-- . _orthocerata_ (plates, fig. to ), containing the genera belemnites, orthoceras, nodosaria, hippurites, and conilites. hippurites certainly has no affinity with the cephalopoda, but is ascertained to be a bivalve shell, properly belonging to the family rudistes; the other genera are straight, elongated, and conical. . _lituacea_ (plates, fig. ), containing the genera spirula, spirulina, and lituola, the two latter of which are microscopic. . _cristacea_, containing the microscopic genera renulina, orbiculina, and cristellaria. . _spherulacea_, containing the microscopic genera miliola, gyrogona, and melonia. . _radiolacea_, containing the microscopic genera rotalites, lenticulina, placentula. . _nautilacea_ (plates, fig. to ). this family contains the following genera--discorbites, siderolites, polystomella, vorticialis, nummulites, and nautilus; the two latter of which alone are now received in cabinets of shells, the four former belonging to that class of microscopic fossils, now termed foraminifera; the genus nummulites, although large, may probably belong to the same class, and perhaps it would have been better to have included the remaining genus, nautilus, in the next family, from which it differs in having the septa which divides the chambers simple at their edges. . _ammonacea_ (plates, fig. to ). the edges of the septa of these are all more or less sinuous and complicated. this family contains the following genera, ammonites, ammonoceras, baculites, and turrilites, the latter of which presents a singular anomaly in having an oblique spire, like that of the order trachelipoda, while it is divided into chambers by sinuous septa. order _monothalamous cephalopoda_. the only shells included in this order belong to the genera argonauta (plates, fig. ), placed here by lamarck, and bellerophon (plates, fig. and ), a fossil genus subsequently added. order _heteropoda_. the singular and beautiful transparent shell contained in this order, under the generic name carinaria, forms a covering to a small portion of an animal, equally remarkable and equally distinct from those of all other orders. the above arrangement, although far from perfect, and requiring numerous modifications, is perhaps liable to as few objections as any other yet proposed, and will certainly be more easily understood by those who have not the opportunity of studying the soft parts of the animal. * * * * * conchological manual. abida. leach. a genus founded on a species of pupa, which has the peristome slightly reflected, and numerous plaits in the aperture. pupa juniperi, pupa secale, draparnaud. great britain; also central and southern europe. abra. leach. a genus composed of amphidesma tenue, prismaticum, and other small thin species. british channel and mediterranean. _fam._ mactracea. absia. leach. lithotrya, sowerby. _fam._ pedunculated cirripedes. acamas. montfort. belemnites multiforatus, blainville. a species described as being perforated at the apex, by a stellated perforation. no species of belemnite at present known agreeing with the description; it is supposed to have been taken from a broken specimen. acanthochetes. a name given to a species of chiton having bunches of bristles at the sides of the valves. acardo. commerçon. described from a pair of bony plates, taken from the vertebræ of the whale, and mistaken for a bivalve shell, destitute of a hinge. acardo. swainson. a generic term applied by swainson to the nearly toothless species of cardium, named c. edentulum by some authors; c. greenlandicum by others: fig. *. acasta. leach. _order_, sessile cirripedes, _lamarck_. balanus _montagui_, sowerby. a small genus separated from balanus, on account of the cup-shaped base, but re-united by sowerby, who shews, in his genera of shells, that this is a merely accidental circumstance, resulting from the situations in which the shells acquire their growth. if, for instance, the balanus be attached to a flat surface, in an open situation, the base will be short and flat; if it be placed in a hollow among other growing substances, it will be lengthened out in order that the aperture of the shell may be even with the outer surface of the surrounding mass; and if, as in the acastæ, it be imbedded in a soft and loose substance, the base, being left to itself, will take a regular form. the acastæ are found imbedded in sponges. _ex._ balanus montagui, of great britain, fig. . also found in the pacific ocean and philippines. acavus. montfort. _fam._ limacinea, blainville; colimacea, lamarck. a division of the genus helix, which may be considered synonymous with de ferrusac's sub-genus helicogena. de montfort has given h. hæmastoma, as an example. fig. . accessary valves, are the smaller or less important testaceous plates, found on the hinge or dorsal margins of the true valves of some shells. example, the small plates on the hinge of pholas, fig. , a. the pholades were placed by linnæus and bruguière among multivalve shells. acephalophora. blainville. (_a_, without; [greek: kephale], head.) the third class of the type malacozoaria, bl. including all bivalve shells, the animals of which have no distinct head. this class corresponds with the conchifera of lamarck, and is divided into the orders palliobranchiata, rudistes, lamellibranchiata, and heterobranchiata, the last of which contains no genera of testaceous mollusca. achatina, auctorum. _fam._ colimacea, lam. (from achates, an agate.) _fam._ limacineæ, bl. _gen._ polyphemus, montf.--_descr._ shell oval or oblong, sub-turrited, light, thin; aperture oval, or pyriform; outer lip sharp; columella smooth, tortuous, truncated, so as to form a notch at its union with the outer lip.--_obs._ it is from this notch that we are enabled to distinguish achatinæ from bulini, which, moreover, generally have a reflected outer lip. the polyphemi of montfort have an undulation in the centre of the outer lip. achatina virginea, fig. . polyphemus glans, fig. . these land shells are found in various parts of the globe, but attain the greatest size and richness of colouring in tropical climates; particularly in the west india islands. achatinella. sow. a small group of shells, differing from achatina in having the inner edge of the outer lip thickened, and a slight groove near the suture of the spire. fig. . sandwich islands. achelois. montf. conilites achelois. knorr. supp. t. , fig. . acicula. nilson. achatina acicula, auct. cionella, jeffreys. aciona. leach. a genus described by de blainville as consisting of those species of scalaria, the whorls of which do not touch each other. if this account be correct, the genus proposed by leach will include the typical species of scalaria, such as s. pretiosa. acme. hartmann. a genus formed of turbo fuscus, walker. auricula lineata, drap. thus described--"shell sub-cylindrical, with a blunt tip; mouth ovate, simple, thin, slightly reflected over the pillar, forming a slight perforation." the animal is said to resemble a cyclostoma, but has no operculum. auricula lineata, drap. hist. , t. , fig. , . southern europe. acteon. montf. tornatella, lam. actinocamax. stokes. a genus of belemnitiform fossils. aculeated. beset with sharp spines, as the margin of chiton aculeatus, fig. . acuminated. terminating in a point, as the apex of melania subulata, fig. . acus. humphrey. terebra of lamarck. acute. sharp, pointed, or sharp-edged. adductor muscle. that which draws the two valves of a shell together, and leaves a mark on the inner surface of each, called the muscular impression. adelosina. d'orb. a genus of microscopic foraminifera. adesmacea. bl. (_a_, without; [greek: desma], _desma_, ligament.) the th family of the order _lamellibranchiata_, bl. composed of mollusca which either bore tubular dwellings in rocks, wood, &c. or live in testaceous tubes, their shells being consequently destitute of the hinge ligament. the action of opening and shutting the valves being limited to the narrow space to which they are confined, or else the valves themselves being soldered into the tube, renders it unnecessary for them to have a ligament to keep them in their places. the genera pholas, teredina, fistulana, and septaria, belong to this family, which corresponds in part with the families tubicolaria and pholadaria, of lamarck. adna. leach. one of the genera separated by leach from _pyrgoma_, and characterized as consisting of an upper valve, supported on a funnel-shaped base, which is not buried in the coral to which it is attached, like pyrgoma, but is seen externally. the operculum consists of four valves. adna, fig. . british channel and mediterranean. adnate. a term applied by some authors to those shells belonging to the family of unionidæ, which have the valves joined together at the dorsal margin, not like other bivalves, by a distinct ligament, but by the substance of the shell itself, the valves appearing to grow together in such a manner that they cannot be separated without one of them being broken as will be seen in our figure of dipsas plicatus, fig. . this circumstance has been made the foundation of specific and even generic distinctions, for which however it is insufficient, because many species which when young are "_adnate_," when fully grown have their valves joined together only by a ligament. Æglia. say. a division of "unionidæ," described as having the "shell cuneate; bosses prominent; cardinal teeth much compressed, placed on one side of the bosses. Æglia ovata, _say_. occidens _lea_. am. tr. iii. pl. ." lardner's encyclopedia of malacology. aganides. montf. orbulites, lam. agathirses. montf. siliquaria, auct. agina ----? belongs to saxicava, auct. akera. bl. the fourth family of the order monopleurobranchiata, bl. containing the genera bulla, bullæa and bellerophon, which, excepting the last, constitutes the family bullæana, lam. akera. a genus of extremely light, horny shells, resembling bulla, from which it differs, in the outer lip being separated from the body whorl, which is elastic. _ex._ bulla fragilis, fig. . alÆa. jeffrey's. a genus of minute land shells, resembling _vertigo_, but separated because they are dextral, while vertigo is sinistral. _ex._ fig. . a. marginata, pupa marginata, drap. found in marshy ground, roots of trees, moss, &c. britain and southern and central europe. alasmodon. say. a division of the genus unio, auct. consisting of those species which have cardinal, but no lateral teeth. _ex._ a. complanatus, fig. . north america and europe. alatÆ. lam. a family of the order trachelipoda, lam. containing the following genera which may be thus distinguished. . rostellaria. sinus close to the canal; including _hippochrenes_, and _aporrhais_, fig. to . . strombus. sinus not close to the canal. fig. . . pteroceras. same, digitated. fig. . alated. (from ala, a wing.) winged, a term applied to shells, when any portion of them is spread out in any direction, as in fig. . hippochrenes, montf. and fig. , unio alatus. alcadia. gray? (b. m. syn. p. ) helicinæ which have a notch in the aperture. a distinction which it is impossible to maintain. see helicina. alatus. humphrey. strombus, auct. alectrion. montf. buccinum papillosum, auct. fig. . alepas. rang. a genus of pedunculated cirripedes without a shell. alveolina. d'orbigny. a genus of microscopic foraminifera. amalthus. montf. a. margaritaceus, montf. is a species of ammonites described as very flat, keeled, with an angular aperture. it belongs to the family ammonacea, lam. amarula ----? a genus composed of melania amarula, auct. and similar species. ambiguÆ. lam. the fourth section of the order conchifera dimyaria, containing the family chamacea, fig. to . amicula. a genus formed for the reception of chiton amiculatus, auct. the valves of which are covered by an integument; so as to be completely hidden externally. amimonus. montf. conilites ungulatus, knorr. a species distinguished only by being slightly curved; _fam._ orthocerata, lam. ammonacea. bl. the fourth family of the order polythalamia, bl. or chambered shells, described as thin, chambered, discoidal, convolute, symmetrical, generally compressed, with visible whorls. this last character is used in de blainville's system to distinguish the ammonacea from the nautilacea. this family contains the genera discorbites, scaphites, ammonites, and simplegas. ammonacea. lam. the seventh family of polythalamous cephalopoda, lam. containing the genera ammonites, orbulites, ammonoceras, turrilites and baculites, to which may be added amalthus, simplegas, ellipsolites, nautellipsites, hamites, icthyosarcolites, and other genera mentioned in the list of figures to . ammonites. auct. (from jupiter ammon.) _fam._ ammonacea, lam. and bl.--_descr._ symmetrical, convolute, discoidal, orbicular; chambers numerous, divided by lobated, branched or sinuous septa, perforated by a siphon; aperture generally more or less modified by the last whorl. the fossils of the secondary strata which compose this genus are numerous and well known; they are vulgarly termed "snake-stones," and some of them are extremely beautiful, particularly when the internal structure is exhibited by a section. there is some difficulty in distinguishing them from the fossil nautili, for although the whorls, being visible and the septa _sinuous_, may be taken as the characteristics of the ammonites, yet there are several species which partake the characters of both. the orbulites of lamarck (fig. ) for instance, have sinuous septa like ammonites, but the last whorl covers those which precede it as in nautilus. simplegas montf. and bl. (fig. ) has the whorls visible externally and the septa simple. ammonites is figured in the plates ( ). ammonoceras, or ammonoceratites. lam. (from _ammon_ & [greek: keras], ceras, horn.) the shells described under this lamarckian genus present an anomaly which is considered by mr. g. b. sowerby, sen., as merely accidental. they resemble the ammonites in internal structure, but instead of being spirally convolute they are merely curved like a horn. _ex._ fig. , copied from de blainville. amnicola. the name of a genus mentioned in the family of melaniana in the conchological part of the synopsis of the british museum, but unexplained. amphibola ----? the same as ampullaria, auct. amphibulima. lam. succinea patula, auct. (fig. .) was first published in the ann. du. mus. d'hist. nat. under the name amphibulima cucullata. the generic name was afterwards abandoned by its author, and the species stands in his system as succinea cucullata. west indies. amphidesma. lam. (from [greek: amphô], _ampho_, _ambo_, [greek: desmos], _desmos_, _ligamentum_). _fam._ mactracea, lam.--_descr._ equivalve, oval or rounded, sub-equilateral, sometimes rather gaping at the sides, with slight posterior fold; hinge with one or two cardinal teeth in each valve, and two elongated lateral teeth, distinct in one valve, nearly obsolete in the other; ligament short, separated from the cartilage, which is elongated and couched obliquely in an excavation of the hinge.--_obs._ in most bivalve shells, the cartilage and ligament are united in one mass, or placed close to each other; the contrary in this case gives rise to the name, which signifies _double ligament_. this circumstance distinguishes the genus amphidesma from tellina, which in other respects it greatly resembles. from lutraria it may be known by its distinct lateral teeth, and also by its valves being nearly close all round, while the lutrariæ gape anteriorly. the species do not appear to be numerous, no fossil species are known. a. _reticulatum_, fig. . west india islands, brazil, coast of pacific, &c. amphipeplea. nilson. the type of this proposed genus is limnea glutinosa, auct. gray's edition of turton, page , plate . fig. . the shell is polished and the inner lip expanded. amphistegina. d'orb. a genus of microscopic foraminifera. amplexus. j. sowerby. a. _corralloides_, fig. . a singularly formed fossil, described as nearly cylindrical, divided into chambers by numerous transverse septa, which embrace each other with reflected margins. it occurs in the dublin limestone, and resembles a coral or madrepore. amplexus. a generic name proposed by captain brown for helix pulchella, drap. , tab. - . zurama, leach. ampullaria. auct. (_ampulla_, a rounded vessel). _fam._ "peristomiens," lam. ellipsostomata, bl.--_descr._ spiral, globular, sometimes discoidal, frequently umbilicated, covered with a rounded, horny epidermis; spire short; whorls rapidly enlarging; aperture elliptical, rounded anteriorly; peristome nearly or quite entire, thickened and slightly reflected; operculum, testaceous, annular, with a subcentral nucleus.--_obs._ this genus of fresh-water shells of which a few fossil species occur, is easily distinguished from other genera, by obvious characters, particularly by a thick, horny, greenish-brown epidermis, and the rotundity in form. one species, the a. cornu-arietis which forms the type of lamarck's genus planorbis, requires notice on account of its flatness, but may be known by the aperture which in the ampullaria is longer than wide, and in planorbis the contrary. lanistes, montf. is described from a _reversed_ species of ampullaria. the ampullaria is vulgarly called the idol shell, and is said to be held in great veneration by the south american savages. the animal has a large bag, opening beneath, placed on the side of the respiratory cavity. it is supposed that the animal has the power of filling this bag with water, and that it is thus enabled to live a long time out of water. they have been brought as far as from egypt to paris alive, packed in saw-dust. _ex._ fig. . east and west indies, north africa, south america, &c. ampullarina ----? a genus formed for the reception of ampullaria avellana. fig. . from australia. ampullina ----? part of the genus helicina, auct. analogous. a term applied to certain species of fossil shells, which present a certain degree of resemblance to recent species; but which are not sufficiently similar to warrant the use of the term 'identical,' or any other implying that they are of the same species. anastoma or anostoma. fischer. (from [greek: ana], _ana_, backwards; [greek: stoma], _stoma_, mouth) _fam._ colimacea, lamark. a genus of land shells so named from the singular circumstance of the last whorl taking a sudden turn and reflecting the aperture upwards, so as to present it on the same plane with the spire; so that the animal walks with the spire of the shell downwards resting on the foot. in other respects, the two species of which this genus is composed, resemble other helices; and belong to de ferrusac's division "helicodonta." _tomogerus_ is de montfort's name for this genus. _a. depressum_ is represented in the plates figs. , . the nearest approach to this genus will be found in the fossil shell named strophostoma, by deshayes, which, however, has no teeth in the aperture and is provided with an operculum like cyclostoma. south america. anatifer. brug. anatifa, lam. this name, which signifies duckbearing, has been given to the shells commonly called barnacles, on account of an absurd notion entertained among the ancients, that they inclose the young of the barnacle duck, in an embryo state. the beautiful bunch of jointed arms, the ciliæ of which serve the purpose of agitating the water, so as to draw in food by the current, were supposed to be the feathers of the future bird. for a description of these shells, see pentelasmis; and fig. . anatina. lam. (_that which belongs to a duck._) _fam._ myaria, lam. pyloridea, bl.--_descr._ thin, transparent, generally equivalve, inequilateral, transverse, marine; hinge with a spoon-shaped process in each valve, containing the cartilage.--_obs._ some species included in the genus anatina of authors, a. striata, for instance, have not the spoon-shaped prominence, but in its place a small, testaceous, moving appendage, connected with the interior of the hinge. these are now separated, and form the genus lyonsia. the genus næara, gray, is composed of anatina longirostrum, and similar species, which have neither the bony appendage nor the spoon-shaped prominence. mya is distinguished from anatina, by the thickness of the shell, and also by having the prominence only in the hinge of one valve. fig. . a. rostrata. the anatinæ are found in the east indies and south sea islands. anatinella. g. b. sowerby. (dimunition of _anatina_). a genus so named from its resemblance to anatina, from which it differs in being destitute of the internal appendage, and having no sinus in the palleal impression. one species having been brought from ceylon, received the name of anatinella sibbaldii. another has lately been found in the philippine islands. fig. . anatomus. montf. tom. , plate . a microscopic shell, appearing from the figure to resemble scissurella. anaulax. brogn. ancillaria, auct. ancilla. lam. ancillaria, auct. ancillaria. auct. ancilla, lam. (_a handmaid._) _fam._ convolutæ, lam. angyostomata, bl.--_descr._ smooth, oblong, subcylindrical. spire short, sutures hidden by enamel. aperture long, anteriorly emarginated and somewhat effuse. columella tortuous, oblique, tumid, truncated.--_obs._ the ancillariæ are pretty shining shells, enveloped almost entirely by the soft parts of the animal. they resemble oliva, from which they are distinguished by the suture of the spire being filled up with shelly enamel, nearly covering the surface. the whorls in oliva being separated by a distinct canal. ancillaria may be known from terebellum by the tumid varix at the base of the columella. the well known ivory shell, eburna glabrata, _lam._ belongs to this genus, of which a few fossil species are found in the london clay, calcaire grossièr and green sand, turin. the recent species are found in the islands of the indian ocean and australian seas. a. glabrata is represented in the plates fig. ; a. cinnamonea, fig. . anculosa. say. _fam._ melaniana, lam. ellipsostomata, bl. a genus proposed to include some fresh-water shells resembling those of the genus melania, the difference between them being that the spire of anculosa is more depressed, and the anterior of the outer lip more angulated than in melania. on an examination of the different species, however, it will be found that this is quite unsatisfactory, as a generic distinction; because some of the species with short flattened spires, have rounded, and others angulated apertures. north america. an example of each is represented, fig. . ancylus. geoffroy. _fam._ calyptracea, lam. otides, bl.--_descr._ thin, obliquely conical, patelliform; apex acute, turned sidewise and backwards; aperture oval; margin simple.--_obs._ although the little fresh-water shells described under this name, resemble those of the genus patella, the animals which produce them are nearly allied to the lymneanæ. and, it may also be observed, that the shells themselves differ from patella in not being quite symmetrical, having the apex turned on one side. a. fluviatilis, fig. . found in great britain, and in southern and central europe, west indies, &c. andromedes. montf. vorticialis, lam. _fam._ nautilacea, lam. a genus of microscopic foraminifera. angulated. (angulatus.) having an angle, or corner, as the anterior of the aperture of eulima, fig. ; the posterior side of castalia, fig. ; the whorls of carocolla, fig. . angulites. montf. a genus composed of species of fossil nautili, described by de blainville as not umbilicated, with a dorsal keel and angular aperture. nautilus triangularis buffon. angiostomata. bl. the third family of siphonobranchiata, bl. described as differing little from the family of entomostomata, but having long, narrow, straight apertures, and the columellar lips straight or nearly so. were it not for the admission of the genus strombus into this family, it would correspond with columellaria and convolutÆ of lamarck. annelides. the ninth class of invertebrated animals, divided into three orders, namely, a. apodes, a. antennés, and a. sedentaires. the last only contains families of testaceous mollusca. the animals are vermicular, some naked, others inhabiting shelly tubes. see sedentary annelides. annular operculum is one which has the nucleus central, or nearly so, the other layers surrounding it in flattened rings. the term concentric is also applied. see introduction. annulated. (annus, a ring.) composed of, or surrounded by rings, as in the case of tubicinella, fig. . anodon. brug. _fam._ submytilacea, bl. nayades, lam. a genus composed of such species of nayades as are destitute of teeth on the hinge. europe, north america, &c. an example is given in a. cataractus, fig. . anomalina. d'orb. a genus of microscopic foraminifera. anomia. _fam._ ostracea, lam. and bl.--_descr._ irregular, inequivalve, sub-equilateral, foliaceous, pearly within; adhering to marine substances by means of a bony appendage, which passes through a large circular opening in the lower valve; muscular impression divided into three irregular portions; hinge destitute of teeth with a short cartilage.--_obs._ the linnæan genus included not only the shells to which the description above given would apply, but also many other genera, such as crania, orbicula, terebratula, &c. which belong to the brachiopoda, and are perfectly distinct. the anomiæ are found in europe, n. america, moluccas, philippine islands, &c. fig. , in the plates, is a somewhat reduced representation of a full grown specimen of a. ephippium. fig. , the hinge of the under valve, with the bony process. fig. , the hinge showing the opening through which it passes. anostoma. see anastoma. ansates. klein. a genus formed of those species of patella which have a produced, recurved beak. helcion, montf. _ex._ patella pellucida, fig. . ansulus or ansylus. mr. gray conjectures that the name of the genus ancylus, should be so written. antenor. montf. a genus of microscopic foraminifera. anterior. in bivalves is the side on which the head, or part analogous to the head of the animal lies; it is known in the shell by the umbones, which if turned at all, are turned towards that part. if there be a sinus in the impression of the mantle, it is always on the posterior part of the shell. if the ligament be placed only on one side of the umbones, it is only on the posterior side. the anterior of a _spiral univalve_ is that part of the outer lip which is at the greatest distance from the apex. of a _symmetrical_ conical univalve such as patella, it is that part where the head of the animal lies, indicated by the interruption of the muscular impression. of _cirripedes_, that part where the ciliæ protrude are anterior; of _brachiopoda_, that part which is farthest from the umbones and which corresponds with the ventral margin in other bivalves. the anterior of _symmetrical, convolute univalves_, is the outer or dorsal part of the aperture, or that part which is farthest from the spire. lamarck and other conchological writers have occasioned much confusion by their errors on this subject; describing the same part of a shell at one time anterior, at another posterior; but generally the reverse of the above arrangement, which is founded upon the natural position of the animal, and generally adopted. the anterior will be indicated by the letter _a_, in figs. , , , , . antigona. schum. a genus composed of venus cancellata, lam. (fig. .) and similar species. antiquated. this word, signifying _out of date_, is occasionally used to express that species of composition which constantly occurs in shells, by each fresh deposit or layer of calcareous matter, forming a new margin, which being replaced by its successor, is no longer used as the margin, and is consequently said to be out of date. apex. this term does not apply to the natural position of a shell, but is used in a mathematical sense, to indicate the nucleus or first formed part; which may be considered as the point of the spiral cone. from this point, the shell enlarging rapidly or slowly as it descends, takes a spiral, arched, straight, oblique, convolute, or irregularly spiral course. the apex will be indicated by the letter _a_, in fig. and . aperture or mouth. the entrance to the spiral cavity of univalve shells. the parts of the aperture are separately described, as follows: the inner lip or labium is that part which lies over the preceding whorl of the shell. it terminates anteriorly, or towards the lower part in what is termed the columella, so called because it forms a kind of axis on which the volutions turn. the outer lip, sometimes called the labrum, is on the opposite side, or the farthest from the axis. if the edges of the inner and outer lips unite all round, they are described as composing the peritrême. in fig. , the aperture is marked by the letter a. aphrodita. lea. (from [greek: aphroditê], greek name of venus.) a genus composed of cardium groenlandicum, auct. fig. *, and other similar species of cardium, the teeth of which are either wholly wanting, or very indistinct. northern ocean. apicial. belonging to the apex. the apicial extremity of the aperture of a univalve shell, is that which is nearest to the apex of the spire. apiculum. humph. trochus, lam. apleurotis. rafinesque. a genus unfigured and imperfectly described as differing in some respects from terebratula and other brachiopodæ. aplexus. fleming. a genus composed of physa hypnorum, drap. &c. and described as having the inner lip simple, and not spread over the body whorl. aplodon. rafinesque. a genus proposed to be established at the expense of the genus helix, but upon what grounds does not appear from the imperfect description which is unaccompanied by a figure. aplustre. schum. a genus formed for the reception of those species of bulla which have the spire uncovered. _ex._ bulla aplustre, (_aplustre_, a flag.) auct. fig. . aplysia. linn. (_a_, without; [greek: pluô], to wash.) _fam._ laplysiens, lam. aplysiana, bl.--_descr._ horny, transparent, clypeiform, or shield-shaped, placed horizontally on the back of the animal, with its convex side uppermost; apex slightly incurved.--_obs._ the animal producing this shell has derived its name from the purplish liquor which it exudes, when disturbed. in contour, it has been fancied to present a certain likeness to a hare crouching, and on this account was called _lepus marinus_, or sea hare, by the ancients. the shell bears a strong resemblance to dolabella, which, however, is much thicker, and more testaceous. the species are found in the mediterranean, european, and west indian seas. a. petersoni, fig. . aplysiacea. bl. the second family of the order monopleurobranchiata, bl. the animals composing this family are either destitute of shells, or are provided with internal ones, which are flat, open, oblique, with the apex or nucleus slightly incurved, not distinctly spiral. this family contains the genera, aplysia and dolabella. the first sub-spiral, with the apex terminal; shell thin, horny. fig. . the second the same, but thick and shelly. fig. . apollon. montf. ranella ranina, auct. placed by de blainville in that division of ranella, which is characterized as being umbilicated. fig. . aporobranchiata. bl. the first order of the second section of paracephalophora monoica, bl. the thecosmata is the only family of this order containing any approach to shells, these are hyalæa and cymbulia. aporrhais. petiver. a genus formed of rostellaria pes-pelicani, _auct._ (fig. ) and similar species. although the shell presents no characters to distinguish it generically from rostellaria, those who have examined the soft parts are convinced that it is distinct. of the three species now known and figured in part i. of thesaurus conchyliorum, by the author, one is common on our own coast, and in the mediterranean; also north america. see rostellaria. aquatic. a term applied by some authors to those species of molluscous animals, which inhabit fresh water, either in rivers, or salt water standing pools, as distinguished from the marine or mollusca. see fresh-water. aquillus. montf. triton lampas, cutaceus, &c. auct. placed by de blainville in the division of the genus triton, which is described as having a short spire, being covered with tubercles and umbilicated. triton cutaceus, fig. . arca. auct. (anglicè, a boat.) _fam._ arcacea, lam.--_descr._ obliquely transverse, subquadrate, equivalve, or nearly so, inequilateral, thick, ventricose, longitudinally ribbed, dentated near the inner margins; hinge rectilinear, forming a flat, external area, upon which the ligament is spread in cross rows, and having a series of small, regular teeth, extending on both sides of the umbones in each valve; muscular impressions distant.--_obs._ the shells composing this genus are easily distinguished from those of all other bivalve shells, by the straight, linear row of small, notched teeth, and by the area between the umbones. the genus _cucullæa_ makes the nearest approach to it in this respect, but it may easily be known from it by the outermost teeth on each side of the row being oblique, and lengthened out; and also by the prominent edge of the muscular impression. these shells are found recent, in various marine localities; fossil, in the tertiary deposits. the arca noæ, formerly regarded as the type of this genus, has, with several other species, been separated from it under the name of bysso-arca, by swainson, on account of an hiatus in the ventral margin, to admit the passage of a byssus; this is not found in the true arcæ. the true arcæ are mostly tropical. arca antiquata, fig. . bysso-arca noæ, . arcacea. lam. a family of the order conchifera dimyaria, characterized by a series of teeth placed on the hinge in a line. the genera may be distinguished as follows, . arca. hinge straight; valves close. fig. . . bysso-arca. valves gaping. fig. . . cucullÆa. distant teeth oblique; posterior muscular impression prominent. fig. . . pectunculus. hinge curved. fig. . . nucula. the same, with a pit in the centre of the hinge, including myopara and crenella. figs. to . . solenella. fresh water, oval; a series of teeth on one side of the hinge, only two or three on the other. fig. . archaias. montf. a genus of microscopic foraminifera. archonte. montf. hyalÆa, auct. arcinella. schum. chama arcinella, auct. arctica. schum. cyprina icelandica, auct. arcuated. (arcus, an arch.) bent in the form of an arch, as dentalium, fig. . area. a flat space or disc, on any part of a shell. as for instance, the triangular space on the hinge of arca, fig. , and spondylus. arenaceous. (arena, sand.) of a sandy texture, as the sand tubes surrounding the bodies of some of the annellides, named arenaria on this account. but the word is more commonly used to intimate the habits of the animal, burrowing with its shell in the sand. arethusa. montf. a genus of microscopic foraminifera. argonauta. auct. commonly called the "paper sailor." _fam._ pteropoda, bl. _order_ cephalopoda monothalamia, lam.--_descr._ light, thin, transparent or nearly so, symmetrically convolute, carinated by a double row of tubercles, terminating smooth or tuberculated ribs radiating towards the centre; aperture large, elongated; peritrême acute, interrupted by the body whorl.--_obs._ the exquisitely beautiful, light and delicate fabrics included under the above name are inhabited by a molluscous animal named the _ocythöe_, which is provided with tuberculated arms. these, hanging over the sides of the aperture, give to the whole the appearance of a vessel propelled by oars: a poetical illusion further heightened by the broad, flat membranes of the two arms, which, when vertically expanded, present an idea of sails. pliny has described the nautilus (the name has been changed by the moderns) as sailing gracefully on the mediterranean waters; and pope has versified the idea in the well known lines "learn of the little nautilus to sail, spread the thin oar and catch the driving gale." scientific men have long been engaged in the interesting discussion, whether the animal really belongs to the shell in which it is found, or whether, having destroyed the rightful owner, it has possessed itself of the "frail bark." it is now, however, proved beyond the shadow of a doubt that the argonaut is the testaceous part of the ocythöe, and that the broad membranes which in some representations have been artificially placed as sails, are naturally bent backwards over the shell like the mantle of some other molluscs. the interesting experiments of madame power, in the mediterranean, have contributed very materially to lead the investigations of naturalists to a satisfactory conclusion. this lady kept a cage under water, in which argonautæ were bred in great numbers, giving her an opportunity of tracing the gradual development of the shell in all its stages, from the elastic and transparent nucleus to the full grown "paper sailor." fig. . arianta. leach. a sub-genus of land shells, containing helix arbustorum, auct. (gray, turton, p. .) arion. a genus of slugs which have no shells. arrow-heads. one of the names by which fossils of the genus belemnites were formerly known. artemis. a genus of bivalve shells, distinguished from those of the genus venus, by having a rounded, denticular form, and a deep, angular sinus in the palleal impression. this does not appear to me to be a sufficient ground of generic distinction, the palleal impressions of the veneres being subject to great variations. british, also from west indies, south america, australia, &c. a. lincta, fig. . articulated. (jointed.) applied to distinct parts of shells, which are fitted or jointed into each other, as the valves of chitones and those of balani. the operculum of nerita is said to be _articulated_ to the columella, having a small process by which it is as it were locked under the edge. see _introduction_. the word is also applied to the cirri, which protrude from the oral openings of cirripedes. articulina. d'orb. a genus of microscopic foraminifera. asiphonibranchiata. bl. the second order of paracephalophora dioica, bl. consisting of spiral univalves, which have no notch or canal at the anterior part of the aperture. this order is divided into the families goniosomata, cricosomata, ellipsostomata, hemicyclostomata, and oxystomata. aspergillum. lam. (from _aspergo_, to sprinkle.) _fam._ tubicolæ, lam. pyloridea, bl.--_descr._ the small, equal, equilateral valves are cemented into, so as to form part of, a large tube; the umbones are slightly prominent outside. the tube is elongated, rather irregular, granulated with sandy particles, and terminated at the base by a convex disc, which is perforated by small pores, elongated into tubes round the edge, presenting a resemblance to the spout of a watering pot, whence the name is derived. _loc._ new holland, java, new zealand, red sea. fig. . aspergillum vaginiferum. assiminea. leach. _fam._ turbinacea, lam.--_descr._ inclining to oval, light, thin, covered with a horny epidermis, spire produced into an acute pyramid; whorls slightly angulated in the centre, rounded beneath; aperture elliptical, slightly modified by the last whorl; inner lip planed; outer lip thin; operculum horny, subspiral. found in brackish water; one species may be procured abundantly on the muddy shores of the thames, in kent. there are also species from calcutta, china, tahiti, and australia. without comparing the animals, it is difficult to distinguish this genus from some species of littorina. fig. . a. grayana. astacolus. montf. a genus of microscopic foraminifera. cristellaria crepidula, lam. astarte j. sowerby. (name of a sidonian goddess, _ashtaroth_ in scripture.) _fam._ nymphacea, lam. genus crassina, lam.--_descr._ suborbicular, equivalve, inequilateral, thick, compressed; hinge with two solid diverging teeth in the right valve, one tooth and a slight posterior elevation in the left; muscular impressions, two in each valve, uniform, united by a simple palleal impression; ligament external.--_obs._ this genus differs from venus, cytheræa, &c. in not having a posterior sinus in the impression of the mantle. the hinge also differs in having but two cardinal teeth. astarte differs from crassatella in having no internal cartilage in the hinge. some of the species are british, others are from america, and one from sicily. the fossils occur in crag, lower oolite, &c. fig. . a. danmoniensis. astrolepas. klein. coronula testudinaria, auct. chelonobia, leach. fig. . atlanta. lesueur. _fam._ pteropoda, lam. and bl.--_descr._ spiral, convolute, transparent, fragile, compressed, with a broad, fimbriated, dorsal keel, and a narrow aperture. this shell, which is called "_corne d'ammon vivant_," is found in the atlantic. the small pteropod, figured in sowerby's genera as limacina, belongs to this genus. atlanta helicialis, fig. . atractodon. charlesworth. (mag. nat. hist. nd series, vol. . p. . ) a genus proposed for the admission of a singular fossil shell, found on the beach at felix-stone, of which the following are the characters;--fusiform, aperture equalling the spire in length, terminating anteriorly in a slightly recurved canal; columellar lip smooth, curved, thickened posteriorly into a blunt tooth; spire obtuse.--_obs._ this shell would be a fusus were it not for the tooth on the posterior extremity of the columellar lip. the only species known is regularly striated in a spiral direction, and named a. elegans. atrypa, dalman. a genus of brachiopodous bivalves, distinguished by the valves being nearly equal, and the umbones not separated by an intermediate area. a. reticulata, fig . attached. shells are attached to marine substances by various means; in some cases by a _byssus_, or a bunch of tendinous fibres passing through an opening between the valves, which gape at their margins to admit a free passage, as in the genera byssoarca and mytilus. in other cases the byssus is of a more compact substance, and passes through a perforation in the shell itself. this is the case with many of the brachiopodous shells, in some species of which the perforation is in the point of the umbones, a specimen of which is represented in the introduction. this species of attachment does not keep the animal motionless, although it is confined to a particular spot. other shells are attached by a portion of their own substance, as in chama, spondylus, serpula, &c. in which instances, the attached valve is motionless, and is termed the under valve. the pedunculated cirripedes are attached by a tubular tendinous process, called a peduncle. attenuated. drawn out, long, thin, tapering, as the extremities of ovulum volva, fig. . atys. montf. a generic name including those species of bulla, which are described as "convolute, with the last whorl covering the rest and hiding the spire, the apex rounded at both ends." bulla naucum, auct. fig. . auricle. (a little ear.) see auriculated. auricula. lam. (dim. from _auris_ an ear.) _fam._ auriculacea. bl. colimacea, lam.--_descr._ oval or oblong, cylindrical or conical; aperture long, narrow, generally narrowest in the centre; rounded anteriorly, with two or three strong folds on the inner lip, and the outer lip thickened, reflected or denticulated; spire short, obtuse, epidermis horny, brown.--_obs._ the above description includes the a. coniformis, f. . and several other conical species with narrow apertures which formed the genus _melampus_, montf. and _conovulus_, lam. the latter author suppressed his genus on ascertaining the conovuli to be land shells. we exclude, however, the a. dombeyana, lam. f. . and several similar species, which being more rounded, having thin outer lips and but one fold on the columella, are described under the generic name _chilina_, gray. it appears rather doubtful whether the auriculæ are marine or fluviatile, but the animals appear to be amphibious. the auriculæ are principally found in salt marshes of tropical climates, some small species are found on the southern european coasts, as far north as britain and south as tierra del fuego. the auriculæ formed a part of the genus voluta of linnæus, f. . a. judæ, f. . a. coniformis. auriculated. some bivalve shells, such as _pecten_, fig. , , have a flat, broad, somewhat triangular appendage on one or both sides of the umbones, called an _auricle_, or little _ear_. if on one side only, they are said to be _uni-auriculated_; if on both, they are said to be _bi-auriculated_. auriculacea. bl. the second family of the order pulmobranchiata, thus described; "shell thick, solid; aperture more or less oval, always large, rounded anteriorly, and contracted by teeth or folds on the columella." this family is included in the genus voluta of linnæus, on account of the plaited columellar lip, a character by which that heterogeneous assemblage of shells is distinguished. it forms part of the family of _colimacea_, lam. from which they differ not only in general form, but also in the fact of the animals being partly amphibious, always living (according to de blainville) on the sea shore, and being occasionally covered with water for a short time. it contains the genera pedipes, auricula, pyramidella. aurifera. bl. otion, auct. auriform. (from _auris_, an ear; _forma_, shape.) ex. _haliotis_, fig. . auriscalpium. megerle. anatina, lam. avicula. lam. (from _avis_, a bird). _fam._ malleacea, lam. margaritacea, bl.--_descr._ inequivalve, inequilateral, foliaceous, subquadrate, oblique, pearly; hinge rectilinear, lengthened into auricular appendages, with a small indistinct tooth in each valve, an elongated, marginal, ligamentiferous area, and an hiatus in the left valve, for the passage of a byssus; one circular muscular impression, near the centre of each valve, with a series of smaller ones arranged in a line towards the umbones.--_obs._ the meleagrinæ of lamarck, margaritiferæ, schum. included in this description, consist of the more rounded species, and do not present the elegant obliquity of form, nor the wing-like auricles from which the genus avicula receives its name. the aviculæ are pearly within. from a. margaritifera, a young specimen of which is figured in the plates, fig. , is obtained oriental pearls. this is an example of meleagrina. a. hirundo, fig. , belongs to the genus avicula of lamarck. it is, however, needless to continue the separation. aviculæ are from e. and w. indies, mexico, coasts of the pacific, mediterranean, british islands, &c. fossil species occur in the london clay, &c. axinus. j. sowerby.--_descr._ equivalve, transverse; posterior side very short, rounded, with a long ligament, placed in a furrow, extending along the whole edge; anterior side produced, angulated, truncated, with a flattish _lunule_ near the beaks. the late mr. james sowerby, who described this shell in the mineral conchology, did not consider his genus as established, not having seen the hinge. axis. the imaginary line, round which the whorls of a spiral shell revolve. the extremities of the axis are pointed out in fig. , by the letters, _a. a._ see "columella." azeca. leach. _fam._ colimacea, lam.--_descr._ "animal like bulinus, with subcylindrical, rather obtuse shell, covered with a polished periostraca (epidermis); aperture pear-shaped, curved and pointed at the top; the margin thick, obtuse, united all round and toothed; the axis imperforated." gray's edition of turton's british shells, page .--_obs._ the turbo tridens of montagu, upon which this genus is founded, resembles bulinus lubricus in general form and character. both these shells differ from the true bulini in having the peritreme entire, and in being pellucid and glossy. azeca differs from bulinus lubricus in having three teeth in the aperture, two on the inner lip and one on the outer. not seeing the necessity for creating a genus on grounds so slight, i have simply transcribed the description given above, leaving others to form their own conclusions as to the propriety of separating this shell from the genus bulinus. britain, central and southern europe. azeca tridens, fig. . azemus. ranzani. conia, leach. baculites. lam. _fam._ orthocerata, bl. ammonacea, lam.--_descr._ straight, conical, tubular, laterally compressed; chambers divided by very sinuous lobed septa, the last elongated; aperture elliptical; siphon dorsal.--_obs._ this genus differs from orthoceras in the same manner in which ammonites differs from nautilus, having its septa sinuated and branched. a baculite might be described as a straight ammonite. this genus is known only in a fossil state. it is found in the cretaceous limestone of maëstricht and valognes. fig. . b. faujasii. balanus. brug. (an acorn; "gland de mer." fr.) _order_ sessile cirripedes, lam. _fam._ balanidea, bl.--_descr._ shell composed of six valves articulated to each other side by side in a circle, by the insertion of lamina; closed at the base by a flat, cylindrical or cup-shaped valve, by which it is generally attached; and at the apex by a conical operculum, consisting of four valves in anterior and posterior pairs. each valve of the shell is divided into a rough triangular portion pointed towards the apex, and a flat area on each side.--_obs._ this description includes the _acasta_ of leach, which growing in sponges, has the base cup-shaped; _conoplæa_ of say, which being attached to the stems of gorgonia and sea-weeds has the base elongated and lanceolate, and _chirona_, gray. balanus is the only genus of sessile cirripedes the shells of which consist of six parietal valves, except _coronula_, which has no shelly base, is flatter, and has the valves of the operculum placed horizontally. the balani are common in all seas, adhering to rocks, corals, floating timber, and to each other. the fossil species are found in the newest strata, at bordeaux, paris, &c. fig. . b. tintinnabulum; . _acasta_ montagui; . balanus galeatus, _conoplæa_, say. balanidea. bl. the second family of the class nematopoda, bl. corresponding with sessile cirripedes, lam., and consisting of coronular multivalves, which are fixed, and in a manner soldered to submarine substances, by the base of the shell; as distinguished from the lepadicea, bl., pedunculated cirripedes, lam., which are attached by a fleshy stalk. the balanidea are composed of two sets of valves, besides the shelly plate or base on which they rest. the first, called the parietal valves, are arranged so as to surround the body of the animal; the second, called the opercular valves, are placed horizontally, so as to cover the aperture. balea. gray. _fam._ colimacea, lam.--_descr._ spiral, turrited, concentrically striated, sinistral, and covered with a thin brown epidermis; spire composed of numerous whorls, gradually increasing in size; aperture small, sub-quadrate; peritrême entire, slightly thickened, with a very slight fold on the columella; axis perforated.--_obs._ a genus of small land shells, found in moss at the roots of trees in britain, not very nearly resembling any other land shells, except clausilia, from which they differ in not having the clausium. they have been placed in helix by de ferrusac, and in pupa by draparnaud. b. fragilis, fig. . _helix perversa_, fer. _pupa perversa_, drap. barbata. humphrey. unio, lam. barnacles. pentelasmis, auct. (fig. .) called anatifa, by linnæus and lamarck, from the ancient notion that they were the eggs or embryo of the barnacle duck. see anatifer. base. in all shells which are attached to sub-marine substances, the base is that part of the shell which forms the point of attachment,--as for instance, the attached valve of spondylus, the basal plate of balanus, the lower part of the peduncle of pentelasmis; in unattached bivalves, the margin opposite to the umbones, where the foot of the animal, or the part analogous to it, protrudes; in spiral univalves, the aperture, which rests on the back of the animal when walking. lamarck and some other authors have used the term _base_ as simply opposed to apex, and apply it to the anterior of the aperture. batolites. montf. hippurites, auct. beak. the apices, or points of the valves of a bivalve shell, generally termed umbones, in descriptions. also any part which is rostrated or drawn out like a beak. beaked. see beak and rostrated. bear's-paw-clam. the common name for hippopus maculatus, a representation of which is given in the plates, fig. . belemnites. auct. ([greek: belemnon], _belemnon_, a dart, or arrow.) _fam._ orthocerata, bl. and lam.--_descr._ straight, conical, consisting of two parts; the _external_ portion forming a thick solid sheath, with a cavity at the base to admit the internal portion or nucleus, which is mathematically conical, and is divided into chambers by smooth simple septa perforated by a lateral siphon.--_obs._ these singular fossils, which are found in most secondary beds, have long attracted the attention of philosophers as well as of the ignorant, from whom they have received the various appellations of thunder-stones, petrified arrows, petrified fingers, devil's fingers, spectre candles, &c. the above description is framed to include the genera hibolithes, porodragus, cetocis, acamas, and paclites of de montfort, and actinocamax, stokes. fig. to . bellerophon. montf. (or bellerophus).--_descr._ convolute, symmetrical, umbilicated, with a double dorsal ridge; aperture wide, semilunar.--_obs._ the fossils composing this genus resemble nautilus in general appearance, but not being chambered shells they approach very near to argonauta, from which they differ only in the thickness of their shell and in roundness of their external form. this genus is erroneously placed by de montfort among chambered shells, and by de blainville next to bulla. it belongs to the monothalamous cephalopoda of lamarck. this fossil is found principally in the carboniferous limestone. fig. , , represent b. tenuifasciata. beloptera. the bony support of a species of cuttlefish, partly resembling sepia. biapholius. leach. a genus believed to be identical with hiatella. bi-auriculated. having two auricles placed at the sides of the umbones, as in pecten, fig. . see auriculated. bicatillus. sw. a sub-genus of "calyptrædæ," including those species, which have cup-shaped internal septa, as for example, calyptræa extinctorium, fig. . biconia. sw. a sub-genus of "calyptrædæ," including those species in which the septum is partly spiral. bifid. divided, double. bifrontia. deshayes. also omalaxis, desh. _fam._ turbinacea, lam.--_descr._ discoidal, planorbicular, with whorls sometimes not contiguous; umbilicus deep, keeled at the margin; aperture subtriangular, somewhat dilated; outer lip acute, separated by a deep notch at both extremities.--_obs._ we do not see any reason for separating this genus from solarium, except the last mentioned character. the few fossil species which this genus contains (solarium disjunctum, bifrons, &c.) are found principally in the paris basin. fig. . solarium bifrons. bi-furcate. double pronged, or having two points. _ex._ the internal appendage of calyptræa equestris, fig. . bigenerina. d'orb. a genus of microscopic foraminifera. bilabiated. having the edge of the outer lip as it were doubled, by one part of the lip being more thickened and reflected than the other, so as to form a ledge, or second lip. bilobate. having two prominent parts, as the outer lip of rostellaria pes-peleeani, fig. . bipartite. composed of or divided into two parts; double; as the valves of platylepas, fig. , each of which has a septiform division in the centre; also the area on the hinge of spondylus. see frontispiece. birostra. sw. a genus composed of species of ovulum, which have elongated extremities, as, for instance, ovulum volva, fig. . birostrites. lam. (double beak.) a fossil formerly considered as a distinct bivalve shell, with conical umbones, and placed in the family of rudistes by lamarck, but now known to be an internal cast of sphærulites, fig. . bisiphytes. described by de montfort as resembling a nautilus, but having two distinct siphons. as no such fossil species is now known to naturalists, it appears probable that de montfort having a specimen of some nautilus, with an accidental depression, took it for a second siphon. bithinia. gray. a genus described as differing from paludina, in having the operculum shelly, and the mouth of the shell thickened internally. paludina impura, auct. fig. . bitomus. montf. a microscopic shell, deriving this general appellation, from the appearance of a double aperture. bivalve. a shell composed of two equal, or nearly equal principal parts, each part having a separate nucleus, turning upon each other by means of a hinge. the class conchifera of lamarck, acephalophora of de blainville severally include the whole of the bivalve shells; the latter name being derived from the fact that the animals have not distinct heads, and neither eyes nor tentacula. all bivalve shells are marine or fresh-water. they form the class dithyra of aristotle. it may be observed that some of the acephalophora, the pholades, for example, have small testaceous pieces fixed on the hinge, which are called accessary valves. these are still fairly bivalve shells, although the genus pholas has been placed by some writers among the multivalves. boar's tusk. a common name given to shells of the genus dentalium. one particular species has received a specific name in accordance with a supposed resemblance, namely, dentalium aprinum, (of a boar.) bonellia. desh. a genus formed, in the first instance, for the reception of bulinus terebellatus, lam. which mr. g. b. sowerby, in his genera of shells, united with the genus pyramidella. m. deshayes, however, in his new edition of lamarck, makes the genus bonellia include several species which i have arranged in the genus eulima. from the remarks of m. deshayes, tom. , p. , , we are led to suppose that the estimated difference between eulima and bonellia consists in the latter having the axis perforated; or in other words, umbilicated. after remarking "que mr. sowerby, junr. confond deux choses bien distinctes, sous le nomme d'eulima," m. deshayes gives the following description of his genus, (translated) "shell turriculated, smooth, polished, with the apex acute and laterally inclined; axis perforated throughout its length; aperture small, entire, angular at the extremities; columella simple and without folds; outer lip thin, simple, nearly parallel with the longitudinal axis." that author further remarks, "mr. sowerby, junr. à signalé cinque espèces vivant, que nous rapportons à notre genre." (sowerby, junr. conchological illustrations, parts and ; , great russell street, bloomsbury.) the species thus selected are e. splendidula, e. marmorata, e. interrupta, e. imbricata, e. brunnea; the two last of which have the umbilicus so inconsiderable, as to be scarcely distinguishable from other species, which m. deshayes has left in the genus eulima, and which have a slight hollow, almost approaching to a perforation, behind the columella. eulima marmorata, (bonellia, desh.) is figured in the plates, fig. . body whorl. the last whorl, constituting the bulk of the shell. borelis. montf. melonia, bl. a genus of microscopic foraminifera. borer or piercer. a term applied to those species of acephalopodous mollusca, which bore holes as dwellings in the rocks, as the pholades, and some others. brachiopoda. lam. a family of symmetrical bivalves belonging to the third section of lamarck's _order_ "conchifera monomyaria," described as bivalve (generally symmetrical) adhering to marine bodies, by a tendon passing through the shell, having no true ligament. what most distinguishes this family and renders it remarkable is the structure of the animal. it has two elongated, tendril-shaped arms. when the animal is in a state of repose these arms are coiled up spirally and enclosed in the shell, but when required for use, are unfolded and extended. this family contains the genera orbicula, terebratula and lingula, in the system of lamarck, to which may be added thecidium, productus, spirifer, magas, pentamerus, crania, strigocephalus, strophomena, and some others enumerated in the explanation of figures to . the above genera may be thus distinguished. . orbicula. umbones central; byssus passing through a hole in the flat valve. fig. . . atrypa. without foramen or space between the valves. fig. . . producta. the same, valves produced, overwrapping; including leptæna. fig. , *. . terebratula. hinge of the upper valve produced beyond that of the other, with a pit or foramen; including _delthyris_, _orthis_, _trigonosemus_, _magas_, _strophomena_. fig. , , , , . . spirifer. the same, with deep triangular area; spiral folds in the interior; including _trigonotreta_ and _cyrtia_. fig. , , . . thecidium. large valve attached; curved ridges in the inner surface; two jutting points or teeth on the hinge. fig. . . crania. attached by the surface of the valve; muscular impressions four, forming a face. fig. , _a_, b. . pycnodonta. irregular; hinge with raised pointed teeth. fig. , . . pentamerus. valves divided by septa; including _gypidia_. fig. to . . lingula. valves equal, gaping, with a peduncle. fig. . brachitoma. swainson. a genus composed of pleurotoma strombiformis and similar species, described as "sub-fusiform; resembling a small strombus or fusus; spire and aperture of equal length; canal short; outer lip slightly ascending, and forming a short canal; sinus very small and nearly semicircular; inner lip thickened above. b. strombiformis, sow. man. fig. ." europe, east and west indies, china, &c. branchifera. bl. the second family of the order cervicobranchiata, containing the following genera of symmetrical univalves:--fissurella, emarginula, and parmophorus. brismÆus. leach. _order._ pedunculated cirripedes. lam.--_descr._ seven plates, three pairs lateral, one dorsal; form cylindrically conical; pedicle not described. _hab._ holes in corals. b. rhophodius, fig. .--_obs._ this minute shell most nearly resembles pollicipes mitellus, fig. *, but the difference may be seen at once by comparing the figures. brontes. montf. this generic name is given to such species of murex as have a very long, closed canal; with a short spire, circular aperture, and are destitute of spires and ramifications. brontes (murex) haustellum, fig. . bucardia. schum. isocardia, auct. buccinum. linn. _fam._ purpurifera, lam. entomostomata, bl.--_descr._ subovate or oblong, covered with an epidermis; spire turrited, consisting of few whorls; aperture wide, subovate, terminating anteriorly in a very short canal, reflected over the back; outer lip simple, slightly reflected; inner lip spread over a portion of the body whorl, terminating in a thick, smooth columella; operculum horny. _hab._ british seas, northern ocean, and coast of africa. most of the fossil species occur in crag, some in upper marine formation and london clay.--_obs._ there are considerable difficulties in keeping this genus distinct from others nearly related to it, into which many of the species run by imperceptible gradations. the genus _nassa_ has been separated on account of the little notch, which terminates the columella. some species of terebra come so close upon the buccina, that it is difficult to say where one genus ends and the other begins. t. buccinoides, fig. . buccinum undatum, the common whelk, fig. . bufo. montf. a generic division of the species composing ranella, characterized as having the shell not umbilicated. _ex._ r. ranina, fig. . the above character is scarcely sufficient in some cases, even as a specific distinction. bulbus. humph. rapella, swainson. a genus formed for the reception of pyrula papyracea, auct. (fig. ), and similar species. rapanus, montf. bulimima. montf. a genus of microscopic foraminifera. bulimulus. leach. _fam._ colimacea, lam. the author is unacquainted with the characters by which the two or three species included in this genus are to be distinguished from bulinus. we have represented, fig. , bulimulus trifasciatus, leach, (bulinus guadaloupensis, auct.) this occurs in the same limestone which encloses the half fossilized human remains from the grand terre of guadaloup. several species are described by the rev. l. guilding in the zoological journal, namely, the b. undulatus, antiguensis, and proteus; but neither from the shells themselves, nor from the figures of the animal, can we draw any information as to the generic character; the difference alleged by mr. swainson and mr. gray being a comparative thinness in the outer lip. bulinus. brug. (bulinus, lam.) _fam._ colimacea, lam. limacinea, bl.--_descr._ oval or oblong, light, covered with a thin epidermis; spire obtuse, variable in length and in the number of whorls, which are generally few; aperture wide, oval, rounded anteriorly; outer lip simple, usually reflected, joining the columella without a sinus; inner lip reflected over part of the body-whorl. the bulini are land shells, found in many parts of the world.--_obs._ the genus bulinus can only be distinguished from helix by its oval form; it forms part of the genus helix of de ferrusac, under the sub-generic designation of cochlostyla. it is known from achatina by the absence of the notch at the point of union between the inner and the outer lips. the young are produced from eggs, which are as firm and opaque as those of birds. (see introduction.) bulinus rosaceus, fig. . b. guadaloupensis, fig. . b. lionetianus, fig. . b. lubricus, fig. . many new species were brought to this country by mr. cuming, and are represented in the conchological illustrations, published by the author at , great russell street, bloomsbury, (in parts , , , , , , , , , to , , .) species occur in europe, west indies, brazil, and south america generally. some small species are british. bulla. auct. _fam._ "bulléens," lam. akera, bl.--_descr._ generally thin, smooth, oval, oblong or cylindrical, more or less convolute; spire short, depressed, or hidden by the last whorl; aperture long, wide in front, gradually narrowing towards the spire; outer lip thin; inner lip spread over a part of the last whorl.--_obs._ the shells composing this genus are very variable in form. the light horny species with an elastic lip is called akera, fig. . the more decidedly convolute species with hidden spires are the atys, montf. b. naucum, fig. . b. lignaria, fig. , is scaphander of leach. the light, thin species, with extremely wide aperture, fig. , is bullæa aperta, lam. the genus bullinula of dr. beck, consists of those species which have more produced spines, fig. . the bullæ are marine, and inhabit all climates. the fossil species occur in tertiary beds. bullÆa. lam. bulla aperta, auct. fig. . bullÆana. ("bulléens, lam.") a family belonging to the first section of lamarck's order, gasteropoda, containing the genus bulla. the genera bullæa, akera, aplustra, atys, scaphander, bullinula, into which it has been divided, may all be fairly included under the name bulla. bullia. gray. a genus of shells partly resembling buccinum, and terebra in general form, being more elongated than the former and more ventricose than the latter. mr. gray remarks in the synopsis of the british museum, page , that the bulliæ resemble the nassæ in most characters, "but they have a very large, broad foot, and the hinder part of the inner lip of the shell being extended beyond the mouth, forms a raised enamelled band round the suture of the whorls, as is also the case with the ancillariæ and some volutes." bullia vittata, fig. , is an example of the genus. the name subula is given by de blainville to the other species of terebra, so that if both these genera were admitted, the old genus terebra must be expunged. bullinula. beck. species of bulla, with produced conical spires, fig. . byssoarca. sw. (_byssus_ and _arca_.) _fam._ arcacea, lam. a genus of bivalve shells, composed of the arca _noæ_, and several other species, separated from the genus arca on account of their shells being attached by means of a byssus passing through an hiatus in the ventral margins. b. _noæ_, fig. . the species occur in southern europe, east and west indies, china; also, on the coasts of great britain. byssomya. cuvier. (_byssus_ and _mya_.) de blainville states that although the shell of this proposed genus resembles saxicava, the animal is sufficiently different to justify the separation. byssus. ([greek: bussos], _byssus_, ancient name for linen.) the tendinous fibres by which some bivalves are as it were anchored or moored to sub-marine substances. a fine example of this is to be seen in the pinnæ which bear some resemblance to large muscle shells and have an hiatus in the margins of the valves through which a bunch of silken fibres passes. in the british museum there is preserved a pair of gloves which have been woven of these fibres. the byssus is peculiar to some bivalve shells such as muscles, hammer oysters, arca noæ, &c. calcar. montf. (a spur.) a genus composed of trochus stellaris, lam. and other depressed species of trochus which are characterized by a stellated keel round the angle of the last whorl; but not including t. imperialis, which is the genus imperator, montf. the difference consists in the latter being umbilicated and the former not. t. stellaris, fig. . calcareous, (_calx_, lime.) a term applied to a shell or to its operculum which is composed principally of lime or shelly matter, as is usually the case, in distinction from one which is of an horny, membranaceous texture. the greater number of shells are calcareous, but it forms an important point of distinction with regard to the operculum. the only difference between the genera trochus and turbo, as at present established, depends upon the calcareous or shelly, and the corneus or horny texture of the operculum. calceola. _fam._ rudistes, lam. and bl.--_descr._ equilateral, inequivalve, triangular; umbones separated by a large triangular disc in the lower valve; cardinal margin straight, linear, dentated; lower valve large, deep; upper valve flat, semi-orbicular, forming a kind of operculum to the lower.--_obs._ this singular shell, known only in a fossil state, in the palæozöic beds, is placed by linnæus in the genus anomia. lamarck places it among his rudistes, but mr. sowerby in his genera of shells, states that it should be added to the family of brachiopoda. fig. , . c. sandalina. callantica. gray. pollicipes hispidus, leach. callia. gray? a genus described as having a peculiarly polished shell like pupina, but wanting the notch. callisostoma. sw. a genus of shells separated from trochus, and thus described, "imperforate; spire elevated, acute; aperture broader than high, transversely ovate, hardly sinuated at the base, and slightly oblique; shells always smooth, and often polished." c. zizyphina is mentioned as an example. callirhoe. montf. p. , vol. . appears to be figured from the nut or inner portion of a large belemnite. calliscapha. gray? iridina nilotica, sow. zool. journ. . pl. . separated from iridina on account of the hinge margin being smooth. callithea. sw. a sub-genus of mitræ, consisting of those species, which like m. sanguisuga, have the "spire and aperture of nearly equal length; internal channel nearly obsolete; shell with longitudinal linear ribs, crossed by transverse striæ and bands; base contracted." swainson mallac. lard. cyclop. callosity. a term used in general zoology to express those hard horny tumidities formed in the skin of some animals, (such as the dromedary, for instance) in those parts which are most frequently used. it is not used in this sense by conchologists, who apply it to those undefined tumidities or bumps which appear on the inner surface and hinge of some bivalve shells, and to the thickening over the umbilicus of naticæ. glycimeris, fig. . natica, fig. , . calpurnus. montf. ovulum _verrucosum_, auct. distinguished by the small circular tubercle at the back of each extremity of the shell. fig. . calyptracea. lam. a family belonging to the first section of the order gasteropoda, lam., the shells of which are described as always external, covering the animal, and having no operculum. the genera contained in this family may be thus distinguished. . calyptrÆa. conical; apex central, septum spiral, cup-shaped, or forked; including _infundibulum_. fig. to . . crepidula. apex terminal; septum flat, reaching half across the aperture. fig. . . capulus. conical; apex obliquely curved, no septum. fig. . . emarginula. apex curved backwards; a notch in the anterior margin; including _parmophorus_. fig. , . . cemoria. a slit _near_ the apex. fig. . . fissurella. a slit _upon_ the apex. fig. . . rimula. a slit near the margin. fig. . . ancylus. apex curved sidewise. fig. . calyptracea. bl. the second family of the order scutibranchiata. bl. thus described: "shell more or less conical, not spiral, or very slightly so; aperture large and entire." the genera included in this family are crepidula, calyptræa, capulus, hipponyx, and notrêma. calyptrÆa. lam. _fam._ calyptracea, lam. and bl.--_descr._ conical, patelliform, irregular, with an internal, lateral, salient plate or septum, varying in form.--_obs._ the internal appendage is in some species cup-shaped, in some it juts out of the centre in a double point; in others it is only a small flap; and in others a spiral disc. these last, which are shaped like trochus, are separated by de montfort under the appellation infundibulum; trochatella, sw. the calyptræa may be known from crepidula by the septum, which in the latter is a flat plate reaching half way across the cavity. fig. , , . camerina. brug. nummulites, auct. camillus. montf. a genus founded upon a minute spiral shell, with a triangular aperture, turned over the back of the last whorl. it is figured in soldani's testacea microscopica. campulotus. guettard. magilus, auct. canal. a groove which characterizes some spiral univalves, where the inner and outer lips unite at the front part of the aperture. this canal is drawn out in some shells to a considerable length, in others it is turned abruptly over the back. the family canaliferæ, lam. (fig. to ), are all provided with this canal. canaliculated. applied generally to any distinct groove or canal. canalifera. (_canalifères_, lam.) a family belonging to the order trachelipoda, lam. nearly corresponding with the family entomostomata in de blainville's system, and described as having a canal of greater or less extent at the anterior part of the aperture. this canal is sometimes straight, sometimes tortuous, and in some genera it is recurved over the back of the shell. all the shells have an operculum, and the thickness of the perfectly formed outer lip does not increase with age. the canalifera are characterized by having a canal, in distinction from the purpurifera, which have only a notch. this family contains the following genera, . cerithium. club-shaped. fig. . . potamis. the same, fresh water. fig. . . nerinea. the same, with internal folds. fig. . . triphora. anterior and posterior canals closed so as to present three openings. fig. , . . telescopium. pyramidal, trochiform. fig. . . pleurotoma. a slit on the upper part of the outer lip; including _clavatula_. fig. , . . turbinella. three horizontal folds on the columella. fig. , . . spirillus. spire papillary; one fold on the columella. fig. . . cancellaria. three folds, and internal costæ. fig. . . fasciolaria. oblique folds, the lowest the largest. fig. . . fusus. fusiform; no folds on the columella. fig. . . pyrula. pear-shaped. fig. to . . struthiolaria. outer lip thickened; sinuated. fig. . . ranella. two rows of varices; a canal at each extremity of the aperture. fig. , . . murex. three or more rows of varices; only one distinct canal. fig. , . . typhis. a tubular perforation between each varix. fig. . . triton. varices not in rows. fig. to . cancellaria. auct. (from _cancellatus_, cross-barred, like window frames or net work.) _fam._ canalifera, lam. entomostomata, bl.--descr. oval, thick, cancellated; spire generally short, pointed; aperture sub-ovate, emarginated anteriorly, pointed at the posterior extremity; outer lip marked within by transverse ridges; inner lip spread over part of the body whorl, terminating in a straight, thick, obtuse columella, with several strong oblique folds. _hab._ indian ocean, coast of africa, america, and west indies. fossils found in london clay and calc-grossier of paris. differing from turbinellus in form and in the transversely ribbed inside of the outer lip. fig. . c. reticulata.--_obs._ the latest enumeration of the species of this genus is contained in a catalogue published by mr. g. b. sowerby, senior, accompanying the author's figures of the new species, amounting to , in parts to of the conchological illustrations. the greater part of these new species were brought to this country by mr. cuming. cancellated. (from _cancellatus_, cross-barred.) applied generally to any shells which are marked by ridges crossing each other as cancellaria, fig. . cancilla. sw. a sub-genus of mitræ, described as having "the whorls crossed by transverse linear ribs; inner canal wanting, plates very oblique; form slender; outer lip thin." _ex._ m. isabella, m. sulcata. cancris. montf. crepidulina, bl. a genus of microscopic foraminifera. canopus. montf. a genus of microscopic foraminifera. canthapleura. guild. a genus composed of those species of chiton, which have the mantle rough, with moveable spines, prickles, or hairs. _ex._ c. spinosus, fig. . cantharidus. montf. trochus iris, auct. and analogous species. elenchus, humph. cantharus. montf. a genus of microscopic foraminifera. canthidomus. sw. a sub-genus of melanopsis, thus described: "spire generally short; whorls coronated with spines, or marked with longitudinal ribs; base obtuse. c. costata, sow. gen. f. ." melanopsis costata, plates, fig. . canthorbis. sw. a sub-genus of the sub-family trochinæ, sw. described as being "nearly disc-shaped: spire but slightly raised; the margin of the body-whorl flattened, and serrated with flat spines; inner lip united to the outer; pillar and aperture as in the last. (tubicanthus.) c. imperialis. mart. . f. ." this sub-genus appears to include those species of which de montfort's genera imperator and calcar are formed. canthropes. montf. described as resembling a nautilus, with the whorls increasing so gradually, that the dorsal edge of the aperture advances but little beyond the last whorl. this genus is not mentioned by blainville or lamarck. capitulum. klein. pollicipes mitellus, lam. fig. *. caprella. ----? plekocheilus, guild. auricula caprella, lam. caprina. d'orb. diceras. auct.? caprinus. montf. (conch. syst. t. . p. .) the figure appears to be intended to represent helix nux-denticulata. capsa. brug. _fam._ nymphacea, lam.--_descr._ equivalve transverse, subequilateral, subtrigonal; cardinal teeth, two in one valve, one notched in the other; lateral teeth remote, obsolete; an external ligament; two muscular impressions in each valve; a large sinus in the muscular impression of the mantle.--_obs._ this genus is so nearly related to donax, that it is difficult to distinguish it at first sight. the capsæ, however, have not the short, plain, straight, posterior side, the distinct lateral teeth, nor the crenulated margins which characterize nearly all the donaces. they are found in the british channel, brazil, and coast of pacific ocean. they are known from erycina by not having the pit in the hinge for the ligament. fig. . c. braziliensis. capulus. montf. _fam._ calyptracea, lam.--_descr._ obliquely conical, posteriorly recurved; apex pointed, sub-spiral; aperture large, rounded, oval; with two muscular impressions, lateral, meeting behind; epidermis horny, rather velvetty. britain, mediterranean, west indies, california, australia. cardiacea. (cardiacées, lam.) a family of the order conchifera dimyaria, lam. most of the genera of shells contained in this family are included in the very extensive family of conchacea, in the system of de blainville. they are described as having irregularly formed cardinal teeth, generally accompanied by one or two elongated lateral teeth. most of the species are ventricose, and have regular radiating ribs. this family contains the genera cardium, cardita, cypricardia, hiatella, isocardia, and others enumerated in the explanation of figures to . their characters may be thus explained. . cardium. two cardinal and two lateral teeth in each valve, including _hemicardium_, _papyridea_ and _aphrodita_, in the last of which the teeth are nearly obsolete. fig. , , *, **. . venericardia. two oblique cardinal teeth, one elongated; including _cardita_, which has the umbones nearly terminal. _pachymya_ may probably be included, but the hinge is not known. fig. , , and . . hippopodium. one elongated cardinal tooth. fig. . . megalodon. hinge broad, septiform, with a large tooth in the centre of one valve. fig. . . isocardia. teeth laminar; umbones spiral. fig. . . cardilia. the same, with a septiform posterior laminar tooth. . hippagus. shaped like isocardia, without teeth. fig. . cardilia. desh. _fam._ cardiacea, lam. a genus formed for the reception of isocardia semi-sulcata, lam. and a small fossil shell, which deshayes had formerly named hemi-cyclonosta michelini; thus described, (translation) "shell oval, oblong, longitudinal, white, heart-shaped, ventricose, with large prominent umbones; hinge with a small cardinal tooth and a pit at the side; a spoon-shaped projection for the reception of the internal ligament; anterior muscular impression rounded, not deep; the posterior being upon a thin, horizontal lamina, projecting in the anterior." deshayes further remarks that although the animal is unknown, the relations of the genus may be established by means of the shell alone. two families contain all the shells which have the internal ligament inserted in a spoon-shaped projection; in the one, that of the anatinæ, the ligament is supported upon a little bone, which is not soldered to the hinge; in the other, that of the mactraceæ, this little bone has no existence. in the former, all the shells are inequivalve; in the latter equivalve. and m. deshayes, considering that the valves are equal, and that there is no separate bone to the hinge, is of opinion that the genus ought to be placed near the lutrariæ, and not far from the anatinæ. c. semisulcata, fig. , . cardinal margin. the edge of a bivalve shell on which the teeth is placed. cardinal teeth. the teeth upon the hinge directly beneath the umbones of a bivalve shell, as distinguished from the lateral teeth, which are placed at a distance on each side. in venus, fig. , the cardinal teeth, are marked by the letter c. cardiocardites. bl. a genus separated from cardita, auct. thus described (translation) "oval species, with the inferior margin nearly straight, or a very little inflated, crenulated and completely closed. _ex._ la c. ajar, adans seneg. pl. . fig. ." cardissa. _sw._ a genus composed of those species of cardium _auct._ which are heart-shaped. _ex._ c. dionæum, fig. . and c. cardissa. cardita. brug. _fam._ cardiacea, _lam._ submytilacea, bl.--_descr._ equivalve, inequilateral, ovate, subquadrate or oblong, marked externally by ribs radiating from the umbones and terminating in a crenulated margin on the inner surface; cardinal teeth in one valve, one long, thick, oblique; another short, more straight; in the other valve one long, oblique, thick. muscular impressions two in each valve, rather oval; palleal impression not sinuated.--_obs._ this description includes lamarck's genus venericardia, which, although consisting of the more oblong species, is not considered sufficiently distinct to justify the separation. cypricardia is distinguished from this genus by a remote lateral tooth. mediterranean, africa, east indies, &c. cardita calyculata, fig. . cardium. auct. _fam._ cardiacea, lam. conchacea, bl.--_descr._ equivalve, sub-equilateral, sometimes gaping posteriorly, ornamented on the outside by ribs radiating from the umbones; cardinal teeth, two in each valve, locked into each other crosswise, lateral teeth, two in each valve, remote; muscular impressions, two in each valve; palleal impression entire. ligament external, inflated.--_obs._ although this genus includes many remarkable forms, the characters are so easily defined that there is no difficulty in distinguishing it from any other genus. c. angulatum, fig. . c. groenlandicum, fig. *. aphrodita, lea. c. hemicardium, fig. **. fig. . c. dionæum. it is somewhat surprising that this genus, which contains some of the most beautiful forms of bivalve testacea, should have been left till quite lately without any attempt to revise the species and settle the synonyms. the author of this manual has endeavoured to remedy this defect by publishing a catalogue of all the species hitherto known, which amount to , including many new species described by him in the "proceedings of the zoological society," in . parts to , and , and to of his conchological illustrations contain figures of species. cardia are frequent in all climates. carinaria. auct. _class_, cephalopoda. _division_, monothalamia, lam. _fam._ nectopoda, bl.--_descr._ symmetrical or nearly so, conical, thin, glassy, fragile, patelliform; with a fimbriated dorsal keel; apex convolute, bent forwards; aperture oval, pointed at the dorsal extremity. _hab._ amboyna, indian ocean, and mediterranean sea.--_obs._ a most singular and beautiful shell, remarkable for its transparency, its fragile structure, and the dorsal keel, whence it derives its name. it was once so rare that a single specimen was known to realize one hundred guineas. fig. . c. mediterranea. carinated. (from _carina_, a keel.) applied to any shell having a raised, thin ledge, passing round a whorl or any other part of a shell, as in carinaria, fig. . carinea. sw. a genus formed for the reception of ovulum gibbosum, auct. and similar species, fig. . carinella. adanson. lutraria papyracea, lam. ligula, leach. _fam._ mactracea, lam. fig. . carinidea. sw. a sub-genus of the genus canthorbis, sw. (turbo.) thus described, "imperforate; spire pyramidal, acute; basal whorl concave beneath, and carinated round its circumference; aperture oval, entire, slightly angulated at the base of the pillar, which turns inwards. c. concavus, martini, , fig. , brevispinosus? sow. gen. (turbo,) fig. ." carocolla. auct. _fam._ colimacea, lam.--_descr._ orbicular, depressed, with the outer sides of the whorls angulated or keeled, whorls few; peritreme reflected; columella contiguous to the axis; epidermis thin.--_obs._ this genus differing from helix only in the whorls being angulated, is hardly distinct enough from the latter to justify the separation. in de ferrusac's system these species constitute the division helicigona, of the genus helix. c. lamarckii, fig. . east and west indies, philippines, south america and europe. cartilage. see ligament. carychium. müll. _fam._ auriculacea, bl. colimacea, lam.--_descr._ oblong or cylindrical, with gradually increasing whorls, few in number; aperture straight, short, with a fold on the columella.--_obs._ this genus of minute land shells differs from auricula chiefly in the soft parts. de furrusac enumerates three species, c. lineatum, c. corticaria, (_odostomia_, flem.) and c. minimum, fig. . de blainville places it in his genus auricula, as "species with two folds and a posterior tooth on the columella," giving a figure of a. mysotis as his example, and quoting the name phitia, gray. europe. cassidaria. lam. (from cassis) _fam._ purpurifera, lam. entomostomata, bl.--_descr._ oval, ventricose, spirally grooved and tuberculated, with a short turrited spire and a large aperture, terminating anteriorly in a recurved canal; outer lip thickened, reflected, undulated or denticulated; inner lip expanded over a part of the body whorl and the columella, with part of its lower edge free.--_obs._ the recent species of this genus are not numerous; the few fossil species occur in the tertiary strata. c. carinata is found in calc-grossier and london clay. in general form this resembles cassis, but is at once distinguished by the canal, which does not turn abruptly back, but is slightly curved upwards. oniscia (c. oniscus, &c. lam.) is distinguished by the shortness of the canal, and the granulated surface of the inner lip. fig. . c. echinophora. mediterranean. cassidea. sw. (from cassis.) a genus composed of those species of the genus cassis, auct. which have the "aperture wide; outer lip never broad or flattened, but sometimes slightly inflected; inner lip spreading, but never dilated or detached beyond the base into a prominent rim." east indies. ex. c. glauca, fig. . cassidula. humph. pyrula, auct. cassidulina. d'orbigny. a genus of microscopic foraminifera. cassis. (a helmet.) _fam._ purpurifera, lam. entomostomata, bl.--_descr._ oval or triangular, ventricose, thick, generally tuberculated, with a short varicose spire; aperture long, sometimes narrow, with the outer lip thickened and reflected, generally denticulated; the inner lip spread over the surface of the body whorl, indented and incrassated at its inner edge; canal turned suddenly over the back of the shell. _hab._ seas of tropical climates. the fossil species are rare, occurring in the tertiary strata.--_obs._ the large, common species of this well known genus are used for shell cameos and as ornaments on chimney pieces, grottos, &c. and are remarkable for the triangular disc, presented by the inner lip, which, in many species, is thickened and spread over the front of the body whorl and the angulated outer lip. the smaller, more rounded species, which have widened apertures, have been separated by swainson, under the generic name cassidea. the c. rufa, coarctata, &c. are formed by mr. stutchbury into a new genus under the name cyprÆcassis, for reasons which will be stated under the word. cassidaria is distinguished by the gradual curve of the canal. fig. is cassis tuberosa, diminished. castalia. lam. _fam._ trigonées, lam.--_descr._ fluviatile, equivalve, inequilateral, trigonal, with corroded umbones; hinge with two laminar, transversely striated teeth, one of which is posterior, remote from the umbones, short, divided, the other anterior, elongated; epidermis thick; internal surface pearly. lamarck, in describing this shell, states, that he regards it as intermediate between trigonia and unio. it should, however, certainly have been placed in the family of "nayades," and perhaps should form a part of the genus unio itself. c. ambigua, lam. fig. . south america. catillus. brong. (a little dish.) inoceramus, sow. catophragmus. sow. (from [greek: katô], _beneath_; [greek: phragmos] _a place_ _paled in_.) _order_, sessile cirripedes, lam.--_descr._ light principal valves, cemented side by side in a circle; eight small pointed valves beneath, covering the joints of the upper circle, and numerous still smaller valves forming the base of the shell; operculum, four valves.--_obs._ this is the only genus of sessile cirripedes, consisting of eight principal valves, excepting octomeris, which is destitute of the accessary pieces from which the genus derives its name. fig. . c. imbricatus. south africa. caudal canal. the elongated hollow process which terminates the aperture anteriorly of some univalve shells. for instance, murex haustellum, fig. , has an elongated caudal canal. cellanthus. montf. vorticialis, bl. a genus of microscopic foraminifera. cellulacea. bl. the second order of cephalophora, bl. consisting of doubtful microscopic bodies, with a number of variously arranged shells, as distinguished from the true polythalamia, bl. or chambered shells. see foraminifera. cemoria. flemingii. leach. a small patelliform shell, differing from fissurella, in having the fissure placed behind the apex, which is produced, pointed and incurved. it is the patella fissurella, müll. patella noachina, chemn. f. noachina, sow. puncturella, lowe. fig. . cemoria flemingii. scotland and tierra del fuego. central. a term used to indicate the position of the muscular impression of a bivalve shell when it is near the centre of the inner surface. it is also applied to the siphon perforating the septum of a chambered shell when it is placed near the centre of the plate. _sub_-central is also used as a comparative term, to indicate the position of the siphon, or of the muscular impression, is _near_ the centre. thus in placuna (fig. ), the muscular impression is central: in exogyra (fig. ), it is _sub_-central. cepa. humph. anomia, linn. cephalophora. bl. the first class of malacozoæ, bl. divided into: _order_ . cryptodibranchiata; . cellulacea; . polythalamacea. the first consisting of cuttle-fish, &c. which are destitute of shells; the second composed of those microscopic cellular bodies, which are regarded as shells by some authors; and the third containing the true chambered shells. cephalopoda. lam. (cephalopodes.) ([greek: kephalê], _kephale_, head; [greek: pous], [greek: podos], _podos_, foot.) the fourth order of the _class_ mollusca, lam. containing molluscs, which are characterized by having a series of arms surrounding the head, which is placed above a sack-shaped body. this order is divided into polythalamia, or many-chambered shells; monothalamia, or single-chambered cephalopods; and sepiaria, or cuttle-fish. fig. to . cepolis. montf. belonging to the genus helix, auct. ceratodes. guild. ([greek: keratôdês], like a horn.) a genus composed of the flat, orbicular species of ampullaria, auct. which present so near a resemblance to the planorbes, as to have been considered as belonging to them. planorbis has, however, a horny texture, and no operculum, and it is always reversed, which may be observed by placing the spire upwards. fig. , represents ampullaria (ceratodes) cornu-arietis. ceriphasia. sw. a sub-genus of melanianæ, thus described, "cerithiform; outer lip thin, dilated at the base; aperture small, slightly emarginate, without any internal groove; inner lip thin. c. sulcata, sw. fig. . p. ." (sw. lard. cyclop. malac. p. .) cerithium. brug. _fam._ canalifera, lam. entomostomata, bl.--_desc._ elongated, ribbed, tuberculated, or rarely smooth, with a lengthened, turrited, pointed, pyramidal spire, consisting of numerous whorls; aperture sub-quadrate, terminated anteriorly by a tortuous canal; outer lip thickened, sometimes reflected, expanded; inner lip thickened posteriorly; operculum horny, spiral, with numerous whorls.--_obs._ the fresh-water shells described as cerithia by lamarck, are separated under the name potamis, and may be known by the thick, horny epidermis. triphora, desh. has the canal closed, except at the extremities. cerithium telescopium, does not appear to present the same characters as the other cerithia, and has been separated by some writers under the generic name telescopium. cerithium aluco, fig. . mediterranean, east and west indies, coasts of the pacific, gallapagos, australia, &c. some small species are british. fossils are numerous in the tertiary beds. cervicobranchiata. bl. the second order of paracephalophora hermaphrodita, bl. containing symmetrical patelliform shells, divided into the families retifera and branchifera. cetocis. montf. _fam._ orthocerata, lam. and bl. placed by de blainville in his section of belemnites, characterized as having small folds at the apex. _ex._ b. penicillatus. cetopirus. ranz. coronula balÆnaris, auct. fig. . chama. auct. _fam._ chamacea, lam. and bl.--_descr._ inequivalve, irregular, thick, foliaceous, attached by the umbo of the lower and larger valve. external ligament placed in a groove, following the curve of the umbones. umbones spiral, coiled round on the back of the valves; hinge with a thick, crenated, lengthened tooth, in one valve, entering a corresponding cavity in the hinge margin of the other; muscular impressions, two in each valve, distinct, lateral.--_obs._ the linnæan genus chama, included the beautiful shells now called tridacna. these are exceedingly different from the true chama, being regular and unattached. the chama (tridacna) gigas, when at its full age and development, is the largest shell known. specimens have occurred weighing upwards of lbs., and measuring two feet across. diceras may be known from chama by the spiral horns into which the umbones are produced; isocardia, by the regularity of the shells, and it is hardly necessary to mention spondylus, which may be known by the triangular disc between the umbones; cleidothærus, stutch. which resembles chama in general form, has a separate bony appendage attached to the hinge, and may, moreover, be distinguished by its elongated muscular impression. fig. , c. lazarus. e. and w. indies. chamacea. bl. the seventh family of the order lamellibranchiata, bl. containing the genera chama, diceras, etheria, tridacna, isocardia and trigonia. chamacea. lam. a family belonging to the order conchifera dimyaria, lam. described as inequivalve, attached, irregular; with or without a single rough tooth on the hinge; with two lateral muscular impressions in each valve. this family contains the genera-- . chama. leafy; umbones spiral. fig. . . etheria. very irregular, pearly, without teeth. fig. . . diceras. like chama, but the umbones free, produced. fig. . chambered. when the cavity of a shell is not continuous, but is divided by shelly diaphragms or septa, it is said to be chambered. this is the case with the shells of the polythalamous cephalopoda, as in the nautilus (see introduction). the character is not confined to these, as it occurs in some species of spondyli, and in several turrited univalves. chamostrÆa. de roissy. cleidothÆrus. stutch. charybs. montf. a genus of microscopic foraminifera. chelibs. montf. a genus of microscopic foraminifera. chelinotus. sw. a genus of "haliotidÆ," sw. including velutina, lam. a species of sigaretus from tonga, and coriocella, bl. thus described, "animal cheloniform, broad; depressed; the mantle larger than the shell, lobed in front; tentacula two, short, obtuse; eyes basal; mouth circular; shell ear-shaped, thin, fragile, imperforate; pillar none." chelonobia. leach. coronula testudinaria, auct. fig. . chersina. humph. achatina, lam. chicoreus. montf. a generic division of the genus murex, consisting of such species as have three ramified varices. _ex._ m. inflatus, fig. . chilina. gray. _fam._ auriculacea, bl. colimacea, lam.--_descr._ oval, thin, covered with an olive green epidermis; spire rather short, consisting of few whorls; aperture large, oval, rounded anteriorly; outer lip thin, joining the inner lip without a sinus; inner lip spread over part of the body whorl, terminating in a thick columella with one or two folds.--_obs._ these shells differ from the true auriculæ in the thinness of the outer lip. c. dombeyana (auricula dombeyana, auct.) fig. . the illustrated catalogue published by the author (sow. conch. illustr. parts , ) contains species. rivers of south america. chilotrema. leach. a sub-genus of helix, containing helix lapicida, auct. gray, turton, p. . chimotrema. ----? belongs to helix. chione. megerle. cytherÆa maculosa, (fig. , c.) sulcata, circinata, &c. auct. and other similar species. chirona. gray. a genus of balanidæ, the shells consisting of six parietal valves and two opercular valves; the upper edges of the parietal valves are sloped and the structure is not tubular. chismobranchiata. bl. the second order of the first section of paracephalophora monoica, bl. those mollusca belonging to this order which have shells, have them either internal or external, but always scutiform, with depressed spires and wide, haliotoid, oblique apertures, without a columellar lip properly so called. this order partly answers to the family macrostomata, in the system of lamarck. it contains the genera coriocella, sigaretus, cryptostoma, oxinoe, stomatella and velutina. chiton. auct. ([greek: chiton], an integument.) _fam._ phyllidiana, lam. _class_, polyplaniphora, bl.--_descr._ oval, consisting of eight arched valves arranged in a series across the body of the animal and fixed in the skin which forms a rim around them, sometimes scaly, spinose, or rugose, sometimes smooth.--_obs._ the genus chiton, commonly called "coat of mail," from its resemblance to jointed armour, remains to the present day in exactly the same state with regard to its boundaries as that in which linnæus found it, and in which he left it. that illustrious naturalist placed it among the multivalves in his purely conchological system, although the animal is totally different from the cirripedes. the shells are prettily marked, and are found attached to the rocks in all seas of tropical and southern climates, but fossil species are almost unknown. fig. , c. spinosus. the genus is divided by guilding into chiton, canthopleura, phakellopleura, chitonellus and cryptoconchus. zool. journ. xvii. p. . the author of this manual has lately attempted a revision of this interesting but neglected genus, and has given a catalogue of all the species hitherto known, as far as they could be identified among the confused mass of synonyms and descriptions to be found in the works of various conchological writers. this catalogue is to be found in his conchological illustrations, and refers to figures of species, of which are contained in parts to , and to . chitonellus. lam. (from _chiton_) separated by lamarck from chiton, on account of the valves being placed at a greater distance from each other, the soft integument of the animal intervening. fig. , c. striatus. philippines. chlorostoma. sw. a sub-genus of "trochinæ." sw. (trochus) of which c. argyrostoma is given as an example. sw. lard. cyclop. p. . chondrus. hartmann. abida, leach. a genus formed for the reception of pupa secale, drap. pupa juniperi, montague, which have plaits in the aperture. chrysoar. montf. probably a species of orthoceras. chrysodomus. swains. "distinguished from fusus, by the comparative shortness of the basal channel, and the ventricose or enlarged shape of the body whorl. the beautiful orange-mouthed whelk of england is a typical example; and the few others now known are all of a very large size, and chiefly found in northern seas, where they represent the more elegant fusi of tropical latitudes; the outer lip is always thin and smooth." sw. page , paragraph , described at page . chrysolus. montf. polystomella, bl. a genus of microscopic foraminifera. chrysostoma. sw. a genus of the family "rotellinæ," sw. thus described "shell turbinate; the whorls few and convex; aperture effuse, round; inner lip thickened just over, and almost concealing the umbilicus. nicobaricus, martini, fig. - ." sw. lard. cyclop. malac. p. . chthalamus. ranz. _fam._ balanidea, bl. order, sessile cirripedes, lam.--_descr._ "shell much depressed, valves thick, thickened at the base, with prominent areas; operculum nearly horizontal, composed of four valves."--_obs._ this description would apply generically to the shell called platylepas in the british museum, only nothing is said about the prominent plates jutting from the internal surface of the valves. the difference between this genus and balanus consists principally in the horizontal position of the operculum, and general flatness of the shell. c. stellatus, fig. . cibicides. montf. a genus of microscopic foraminifera. cidaris. swains. a genus composed of turbo smaragdus, petholatus, and other similar species. the word cidaris is, however, already in use for a genus of echinæ. cidarollus. montf. a genus of microscopic foraminifera. ciliated. (ciliæ, hairs.) having minute hairs as in orbicula, lingula, &c. and the jointed feelers of the cirripedes. cimber. montf. navicella, auct. cineras. leach. (_cinereus_, ash-coloured.) _order_, pedunculated cirripedes, lam.--_descr._ animal with a quadrilateral body, supported on a fleshy peduncle, with an opening in front of the upper part for the passage of a bunch of ciliated tentacula. immediately above this aperture is a pair of small elongated valves, placed in a nearly horizontal position; at the lower part is another tripartite pair placed perpendicularly, one on each side, and a narrow, angulated, keel-shaped piece placed at the back.--_obs._ the nearest approach to this genus is otion. (c. vittatus, fig. .) found upon substances floating in the sea. cinereous. (_cinereus_) ash-coloured. cingula. fleming. rissoa, leach. cionella. jeffreys. _fam._ colimacea, lam.--_descr._ oblong or elongated; last whorl large; apex rather acute; columella, sub-interrupted; aperture canaliculated, sub-effuse at the base; margins very unequal; no umbilicus. bulinus octonus, lubricus, acicula, &c. auct. c. lubrica, fig. . circe. schum. venus castrensis, fig. d. v. sulcatina, arabica, pectinata, auct. and other similar species. cirripedes. lam. the tenth class of invertebrated animals, so named from the curled and ciliated branchia which protrude from the oval aperture of the shells. the class cirripedes of lamarck constitutes the entire genus _lepas_ of linnæus. they are divided into two sections; first, sessile cirr. attached by the basal portion of the shell; second, pedunculated cirr. supported upon a peduncle. figs. to . cirrobranchiata. bl. the first order of paracephalophora hermaphrodita, bl. this order has been formed for the purpose of giving a place in the system to the genus dentalium. the animal of which has lungs, consisting of numerous filaments, having their basal origin in two radical lobes under the neck. cirrus. j. sowerby (cirrus, a tendril.) _fam._ turbinacea, bl. and lam.--_descr._ spiral, conical, with a hollow axis; whorls contiguous, numerous, rounded, or slightly angulated.--_obs._ this fossil genus resembles trochus, from which it is known by the deep funnel-shaped umbilicus. fig. , c. nodosus. cistula. humph. cyclostoma, lam. clanculus. montf. trochus _pharaonis_, lam.--_obs._ this, with several other species, belong more properly to monodonta, lam. odontis, sow. fig. . clathodon. conrad. gnathodon, gray. clausilia. drap. (_clausium_, a valve or folding door.) _fam._ colimacea, lam. limacinea, bl.--_descr._ spire elongated, consisting of many volutions; aperture small, sub quadrate, having several tooth-shaped folds on the columella. a small, elastic, shelly plate, attached to the columella within, called the clausium, its office being to enclose the aperture when the animal has retired within the shell.--_obs._ this last character distinguishes it from the pupæ, to some of which it bears a very near resemblance. _hab._ land, in the central and southern parts of europe, several british species. fig. , c. macascarensis. clausium. a name applied to the beautiful contrivance whence the genus clausilia derives its name, consisting of a little bony tortuous plate, placed in a groove on the columella. here it serves the purpose of a door, which, when not prevented by counteracting pressure, springs forward on its elastic ligament, and encloses the animal in his retirement. the aperture is opened by pushing back the clausium into the groove. clausulus. montf. conch. syst. , . a genus of microscopic foraminifera. clava. humph. cerithium, lam. clavagella. lam. (_clava_, a club.) _fam._ tubicolæ, lam. pyloridea, bl.--_descr._ two irregular flattish valves, one fixed or soldered, so as to form part of the side of an irregular shelly tube; the other free within the tube near the base.--_obs._ the shells composing this genus are found in stones, madrepores, &c. and appear to form the connecting link between aspergillum, which has both valves cemented into the tube; and fistulana, in which both are free. fig. , a fossil clavagella. found recent on the coast of malta and new south wales. clavalithes. sw. a genus composed of some fossil shells, separated from the genus fusus, which, having the general form of turbinella rapa, &c. are considered by swainson, as holding an intermediate station between fusus and the turbinellidæ.--_descr._ "unequally sub-fusiform; the body whorl, and spire, being conic; and the canal suddenly contracted and attenuated; terminal whorls papillary; inner lip thick; pillar smooth, c. longævus, clavellatus, noæ, ponderosus, sw."--_obs._ the papillary spire may form a sufficient reason for separating this genus from fusus, while the absence of plates on the columella places them at a still greater distance from turbinella. clavate. when one extremity of the shell is attenuated, and the other becomes suddenly ventricose or globular, it is said to be clavate. _ex._ murex haustellum, fig. . clavatula. lam. the generic name by which lamarck originally distinguished those species of pleurotoma which were remarkable for the shortness of their canals. in his system, however, they are re-united to pleurotoma. fig. , p. strombiformis. clavicantha. sw. a genus separated from pleurotoma, lam. consisting of species, which are described as "thick, sub-fusiform; the surface rugose, and the whorls sub-coronated; channel short; slit assuming the form of a short, broad sinus. c. imperialis, e. m. , spirata, e. m. , fig. , conica, e. m. , fig. , echinata, e. m. , fig. , auriculifera, e. m. , fig. ." clavicle. (_clavis_, a key.) a little key. this term is applied to the bony appendage in the hinge of some species of anatina, (those included in the generic term lyonsia) cleidothærus, myochama, &c. clavulina. d'orb. a genus of microscopic foraminifera. clavus. montf. a genus of microscopic foraminifera. cleidothÆrus. hutch. ([greek: thairos], hinge, [greek: kleis], clavicle.) _fam._ chamaceæ or myariæ, lam.--_descr._ inequivalve, irregular, solid, attached; with one cardinal, conical tooth in the free valve, entering a corresponding indenture in the other; and an oblong shelly appendage, fixed by an internal cartilage in a groove under the umbones; muscular impressions, two in each valve, one elongated, the other uniform.--_obs._ this shell is like chama in general form, but is distinguished by the clavicle or shelly appendage from which its name is derived. fig. . new south wales. cleodora. _per. et les. fam._ pteropoda, lam. thecosomata, bl.--_descr._ thin, transparent, pyramidal, with flat alate sides, and oval aperture. fig. , c. cuspidata. clisiphonites. montf. microscopic. lenticulina, bl. clithon. montf. neritina corona, spinosa, &c. auct. fig. . clitia. leach. _fam._ balanidea, bl. _order_, sessile cirripedes, lam.--_descr._ sub-conical, compressed, consisting of four unequal valves, two larger and two smaller, joined together side by side, by the interlocking of their dentated edges, a process somewhat like that which joiners call dove-tailing. operculum, consisting of two unequal pointed valves.--_obs._ clitia is known from creusia, by the articulations of the valves, and by the operculum, which in creusia consists of four valves. fig. . c. verruca, (lepas verruca, gmelin.) britain and peru. close. the margins of a bivalve shell are described as being close, when there is no hiatus between them in any part, otherwise they are described as _gaping_. clotho. faujas. _fam._ conchacea, bl. more properly belonging to the pyloridea, bl.; and the lithophagidæ, lam.--_descr._ "oval, nearly regular, longitudinally striated, equivalve, sub-equilateral; hinge consisting of a bifid tooth, curved like a crochet, larger in one valve than in the other." this description is translated from blainville, who states that he has never seen the shell. annales du museum d'histoire naturelle, tom. , pl. , fig. - . clypeiform. (_clypeus_, a shield.) open, flat, shaped like a shield or buckler, as umbrella, fig. , and parmophorus, fig. . clypidella. sw. a sub-genus of fissurella, described as having one extremity of the shell slightly raised. c. pustula. sow. gen. fig. . coat of mail. a common name given to shells of the genus chiton, on account of their resemblance to jointed armour. cobresia. hübner. vitrina, auct. cochliate. (_cochleare_, a spoon). applied to any shell or part which is hollow and oval, as patellæ, &c. the cavity containing the cartilage in mya, fig. , is cochleate. cochlicella. one of the sub-genera into which de ferrusac has divided the genus helix, consisting of bulinus decollatus, fig. , and similar species. see helix. cochlicopa. fer. a sub-genus of helix, partly corresponding with polyphemus of de montfort, and consisting of species of achatina, which have the outer lip undulated. cochlitoma. fer. a sub-genus of helix, corresponding with the genus achatina, auct. not including those with undulated outer lips. cochlodina. fer. a sub-genus of helix, including the genus clausilia, auct. cochlodonta. fer. a sub-genus of helix, containing pupa uva, auct. &c. cochlogena. fer. a sub-genus of helix, containing pupiform shells, such as azeca tridens, fig. . cochlohydra. fer. a sub-genus of helix, composed of the genus succinea, auct. cochlostyla. fer. a sub-genus of helix, composed of the genus bulinus, auct. colimacea. lam. this family, of the order trachelipoda, lam. includes all land shells, which might with propriety be divided into three sections, the first of which contain the following well-known genera:-- . succinea. oval, transparent, oblique; animal amphibious. fig. , . . helix. the type of which is the common snail shell. the separation of _carocolla_, on account of the angulated whorls, or that of _geotrochus_, on account of the turbinated shape, cannot be well maintained. fig. , , , to , to , . . anostoma. the aperture turned up towards the spire. fig. , . . streptaxis. whorls excentric. fig. , . . bulinus. oval; aperture entire, including _bulimulus_, _balea_, _cionella_, _azeca_. fig. to , , , . . achatina. a notch terminating the columella. fig. to . . pupa. cylindrical; including _vertigo_, _alæa_, &c. fig. to . . clausilia. cylindrical, with a clausium. fig. . _obs._ the above are united in the system of de ferrusac under the generic name helix, and divided into sub-genera as explained under that word. the next section, included in the family auriculacea, bl., contains the genera auricula, chilina, carychium, marinula, scarabæus, and partula. fig. to . the third section contains the following genera of land shells with opercula. . cyclostoma. aperture round; operculum spiral. fig. , . . nematura. last whorl contracted; operculum spiral. fig. . . helicina. aperture semi-lunar or angulated; operculum concentric. fig. , . . pupina. shell polished; operculum concentric; aperture round. fig. . . strophostoma. aperture turned up towards the spire, like anostoma, but said to have an operculum. only known fossil. fig. . columbella. auct. (columba, a dove.) _fam._ columellata, lam.--_descr._ thick, oval, or angular; with short spire, and long narrow aperture, contracted in the centre, and terminating in a short canal; outer lip thickened and dentated; inner lip irregularly crenated. epidermis thin, brown. operculum very small, horny.--_obs._ those species of mitra, which resemble columbella in shape, may easily be distinguished by the plaits on the columella. the columbellæ are marine, and few fossil species are known. fig. , c. mercatoria. swainson has divided this genus into the following: _columbella_, consisting of c. mercatoria, &c.; _pusiostoma_, consisting of the strombiform species; _crassispira_, which is most probably a cerithium; _nitidella_, consisting of the smooth species; _conidea_, consisting of the more conical species; another set of the more conical species has been removed from this family, and placed in that of the "coninæ," but as they are separated by no essential character, we suppose this has merely been done for the purpose of completing the "circle" of the last mentioned family, which otherwise would not have reached the required number of five. mediterranean, east and west indies, south america, coast of california, gallapagos, &c. columella. a solid column formed by the inner sides of the volutions of a spiral univalve. it is sometimes described as the inner lip of the aperture, of which it forms a part; but the term would be more properly confined to that portion of the inner lip which is seen below the body whorl, over which the remainder of the lip is frequently spread. all the inner edge of the aperture, including that part of it which covers the body whorl, is called the columellar lip. in fig. , the anterior termination of the columella is indicated by the letter c. the axis, is an imaginary line drawn strictly through the centre of the whorls, whether their inner edges form a solid column or not. columellar lip. the inner lip. see columella. columellata. lam. a family of the order trachelipoda, lam. containing the following genera:-- . mitra. elongated; aperture narrow; strong folds on the columella; including _mitrella_, _mitreola_, _tiara_, and _conohelix_. fig. , . . marginella. outer lip reflected; including _volutella_, _persicula_, _gibberula_, and _glabella_. fig. . . columbella. outer and inner lips denticulated or granulated. fig. . . voluta. outer lip thickened; folds on the columella; aperture generally wide; apex papillary; including _scaphella_, _harpula_, _volutilithes_, _cymbiola_. fig. , . . melo. shell comparatively light; spire short, sometimes hidden; apex round, spiral; folds on the columella laminar. fig. . . cymba. upper edge of the aperture separated from the body whorl by a flat disc; apex mammillated, irregular; folds on the columella. fig. . . volvaria. cylindrical; aperture long, narrow; folds on the columella; spire hidden. fig. . colus. humphrey. fusus, lam. complanaria. sw. a subgenus of alasmodon (unio), thus described, "shell winged; the valves connate; the bosses very small and depressed; cardinal teeth two or three; lateral teeth represented by irregular grooves. c. gigas (unio), sow. man. fig. . alasmodon complanatus, say. c. rugosa, sw." compressed. pressed together, or flattened. the application is the same as in common use. a patella may be described as a vertically compressed cone. a ranella, on account of the two rows of varices skirting the whorls, appears, as it were, laterally compressed. a bivalve shell is said to be compressed when it is flat, that is, when but a small cavity is left in the deepest part when the valves are closed. perhaps the placuna placenta, fig. , is the most remarkable instance of this. concamerations. (_con_, with, _camera_, a chamber.) a series of chambers joining each other, as in nautilus, spirula, &c. concentric. a term applied to the direction taken by the lines of growth in spiral and other shells, (_longitudinal_ of some authors.) every fresh layer of shelly matter forms a new circle round an imaginary line, drawn through the centre of the spiral cone, down from the nucleus. when the edges of the successive layers are marked by any external characters, the shell is said to be concentrically striated, banded, grooved, costated, &c. a fine illustration of the latter is to be seen in the scalaria or wentletrap, fig. , lines, bands, ribs, &c. in the opposite direction, (_transverse_ of some authors,) are "radiating" in bivalves, as the ribs of cardium, fig. , and "spiral" in univalves, that is, following the direction of the whorls, as the bands of colour in pyramidella, fig. . conchacea. bl. the eighth family of the order lamellibranchiata, bl. the shells are described as follows: nearly always regular, valves closed all round; apices curved towards the anterior; dorsal hinge complete, with teeth and ligament; the latter external or internal, short and thick; two distinct muscular impressions, united at the lower part by a parallel impression, which is frequently sinuated at the posterior. the genera described in this family are divided into three sections. first, those which are regular, and have distant lateral teeth, cardium, donax, tellina, lucina, cyclas, cyprina, mactra, and erycina. second, those which are regular, and have no distant lateral teeth, crassatella and venus. third, those which are irregular, venerupis, coralliophaga, clotho, corbula, sphænia, and ungulina. conchacea. lam. a family of lamarck's order conchifera dimyaria. regular, unattached in general, closed at the sides. they are always more or less inequilateral. the _marine_ conchacea are those which inhabit the sea. the fluviatile conchacea are those which are found in rivers, ponds, &c. each of these contain various genera, which may be arranged as follows:-- _fluviatile._ . cyrenella. three cardinal teeth; ligament long; shell thin. fig. . . cyclas. thin, oval; cardinal and lateral teeth; anterior side shortest, including _pera_. . pisidium. the same, with the posterior side shortest. fig. . . cyrena. thick; cardinal and lateral teeth. fig. . . potamophila. two thick cardinal teeth. fig . _marine._ . cyprina. two cardinal teeth, and one remote lateral tooth. fig. . . venus. three cardinal, no lateral teeth; including _artemis_. fig. , , a. . cytherea. several cardinal teeth; one very short lateral tooth. fig. , _a_, _b_, _c_, d. . pullastra. cardinal teeth notched, otherwise like venus. fig. . . astarte. three cardinal teeth; ligament short. fig. . venericardia belongs to the cardiacea. conchifera. lam. the th class of invertebrata, consisting of all those animals which have bivalve shells. lamarck divides the class into dimyaria, which have two adductor muscles; and monomyaria, which have but one. concholepas. montf. (concha, a shell; lepas, a stone or rock.) _fam._ purpurifera, lam. entomostomata, bl.--_descr._ oval, imbricated, thick; with a very short spire and large oval patelliform aperture, terminating anteriorly in a slight emargination; outer lip crenated, with two produced points or teeth towards the anterior, inner lip smooth, nearly flat, reflected over the last whorl, so as nearly or entirely to cover it; operculum horny. marine, only one species known, from peru.--_obs._ this shell is placed near patella by lamarck, on account of its large open aperture; but having a horny operculum, and resembling purpurea in other respects. fig. . concholepas peruviana. conchotrya. gray. (_concha_, a shell; [greek: truo], (_tryo_) to bore.) _order_, pedunculated cirripedes, lam.--_descr._ five pieces, two pairs ventral, one single; shaped like pentelasmis. found in holes. conchyliomorphite. a term used by de blainville to designate the cast or model of a fossil shell, formed by a siliceous substance which has entered or surrounded it when in a liquid state, and subsequently become hardened into flint. the shell has afterwards decomposed or fallen off by accident, leaving its external or internal characters to be conjectured from the monumental impressions that remain. conchyta. hupsch mus. calceola, lam. cone. a common name for shells of the genus conus. cone. this mathematical term is used by conchologists in its utmost latitude of signification to express a body, which in its formation, commences in a small point, called the apex, and increases in width towards the conclusion or base. it is applied to all shells, whether the increase in width be gradual or sudden; or whether in its growth, it takes a straight, oblique, curved, or spirally-twisted course. in this sense, a bivalve would be described as a pair of rapidly enlarging, oblique cones, and the aperture of every spiral shell would be its base. but this phraseology being in disuse, it is only mentioned here that it may be understood when occasionally met with. conella. sw. a genus composed of species of the genus columbella, lam. which have a conical form, and which, on that account, are considered by swainson as belonging to his family of coninæ. swains. lardner. cyclop. malac. described at p. . c. picata, sw. fig. , a. p. . confluent. a term applied to two parts of a shell when they gradually flow into each other, as, for instance, the inner and outer lips of univalves when they pass into each other at the anterior extremity, without the intervention of a notch or angle. conia. leach. _fam._ balanidea. _order_, sessile cirripedes, lam.--_descr._ four rather irregular valves, of porous structure, placed side by side, so as to form a circular cone, supported at the base on a shelly plate, and closed at the aperture by an operculum consisting of four valves in pairs. distinguished from creusia by its porous structure and by its flat support; that of creusia being cup-shaped. fig. , conia porosa. conical. a term applied in the ordinary sense, and not as explained above, under the word cone. conidea. sw. a genus separated from columbella, lam. thus described, "mitra shaped, fusiform; spire equal or longer than the aperture; the whorls tumid; outer lip slightly gibbous above, contracted below; margin not inflected; striated within; inner lip terminating in an elevated ridge, but with the teeth obsolete. c. semipunctata, (_columbella_, lam.) mart. . fig. , ." africa. conilites. _fam._ orthocerata, lam. & bl.--_descr._ "conical, straight or slightly curved; having a thin external covering, independent of the nut or alveole, which it contains. alveole transversely chambered, sub-separable." (translated from lam.)--_obs._ the difference between belemnites and conilites is that the external sheath of the latter is thin, and not filled up with solid matter, from the point of the alveole to the apex, as in the former. de blainville places in this genus the genera thalamulus, achelois and antimomus, montf. two of which are figured, knor. sup. fab. iv. fig. . . . . conilites pyramidatus, fig. . conilithes. sw. a sub-genus of coronaxis, sw. (coni, with coronated whorls) thus described, "conic; spire considerably elevated; the aperture linear, c. antediluvianus, sow. gen. f. ." conohelix. sw. (_conus and helix._) the generic name given to those species of mitra which are conical in form. fig. , c. marmorata. conoplÆa. say. _order_, sessile cirripedes, lam. a genus composed of balani, attached to the stems of gorgonia, having their bases elongated. _ex._ fig. , balanus galeatus. conorbis. sw. a genus composed of species of conus, such as c. dormitor, (sowerby, gen. fig. ) which have elevated spires and the upper part of the outer lip deeply sinuated. mr. swainson considers these fossil species as analogous to the pleurotomæ. _sw._ lard. cyclop. malac. p. . conovulum. a genus proposed by lamarck, to include the small, conical species of auricula, which have the outer lip simple. this genus was afterwards abandoned by the author. _ex._ fig. , auricula coniformis. contiguous. (_contingo_, to touch.) a term applied to the whorls of spiral shells when they rest upon, or touch each other. this is the case in a great majority of instances. when, on the contrary, there is a space between the whorls, they are said to be non-contiguous, detached, or free. examples of non-contiguous whorls are to be seen in scalaria, fig. (in this case, the distance between the whorls is small), and in crioceratites, fig. . a "_columella contiguous to the axis_," is when in the centre of the shell and takes the place of the imaginary line which forms its axis. continuous. carried on without interruption, as the siphon in spirula, the varices in ranella, fig. , which, occurring in a corresponding part of each whorl, form a continuous ridge. conularia. miller. a genus of orthocerata, described as conical, straight, or nearly so, divided into chambers by imperforate septa; aperture half closed; apex solid, obtuse; external surface finely striated. resembling orthoceras, but wanting the siphon. fig. . conus. auct. ([greek: kônos], a cone.) _fam._ enroulées, lam. angyostomata, bl.--_descr._ conical, convolute, with a short spire, consisting of numerous whorls; and narrow lengthened aperture, terminating in a slight emargination at each extremity; outer lip thin; epidermis thin; operculum small, pointed, horny.--_obs._ this well-known genus of shells is easily distinguished from any other, by its conical form, its smooth columella, its narrow aperture, and thin outer lip. the form of the spire varies from flat and even partially concave, to a regular pyramidal cone; and the upper edges of the whorls are rounded in some species, angulated in others, and in some are waved or coronated. the variety of marking and the numerous delicate tints of these shells have caused them to be highly appreciated by amateur collectors; and many species, as the c. ammiralis, or admiral; the c. gloria maris, or glory of the sea; the c. cedonulli ("i yield to none"), and others, have always produced good prices in the markets. we give figures of the principal forms, as expressed in the genera proposed by de montfort, of rhombus, hermes, rollus and cylinder, in figures to . many new species were brought to this country by mr. cuming, and are represented in parts , , , ; , , , ; , , , ; , ; to of the conchological illustrations, by g. b. sowerby, jun. see coronaxis, swainson. the cones are mostly tropical, some are found as far north as the mediterranean, and south as the cape of good hope. the most beautiful species are from the east and west indies. convolutÆ. (enroulées, lam.) a family of the nd section of the order trachelipoda, lam. the genera of which may be distinguished as follows:-- . cyprÆa. lips thickened, inflected, with teeth; spire hidden, including _cypræovulum_, _luponia_, _trivia_. fig. to . . ovulum. lips thickened, inflected, with slight crenulations; spire hidden. fig. to . . erato. lips thickened, inflected; spire visible; a groove down the back. fig. . . terebellum. cylindrical, open at the anterior extremity; columella smooth; suture of the spire canaliculated. fig. , . . oliva. columella plaited, swelled into a varix at the anterior. fig. , . . ancillaria. the same, but the suture of the spire covered with enamel. fig. , . . conus. turbinated, numerous whorls; spire flat or short, conical; columella smooth. fig to . convolute. (_con_, together; _volvo_, to revolve). this term can be strictly applied only to symmetrical shells, signifying that the volutions are parallel to each other in a horizontal direction, as in the ammonites, &c.; but the term is also commonly used in describing such shells as conus, in which, the direction of the whorls being scarcely oblique, the last whorl almost entirely covers those which precede it. this is the case with lamarck's family of enroulées. fig. to . coralliophaga. bl. cypricardia coralliophaga, lam.--_descr._ oval, elongated, finely striated from the apex to the base, cylindrical, equivalve, very inequilateral; umbones slightly raised and quite anterior; hinge nearly the same in both valves; two small cardinal teeth, one of which is bifid, placed before a kind of lammellated tooth, beneath a very slender external ligament; two small, distant, muscular impressions, united by a striated palleal impression, which is strongly striated posteriorly.--_obs._ this shell, which is found in the empty holes of dead lithodomi, in some instances conforming its shape to its situation, differs from cypricardia of lamarck, principally in its cylindrical form. c. carditoidea, fig. . mediterranean and east indies. corbicula. megerle. cyrena, lam. corbis. cuv. (_a basket._) _fam._ nymphacea, lam.--_descr._ transverse, oval, thick, ventricose, equivalve, sub-equilateral, free, cancellated, with denticulated internal margins; hinge with two cardinal and two lateral teeth in each valve; of the latter, one near and one remote from the umbones; muscular impressions lunulate, two in each valve, united by an entire palleal impression, without a sinus.--_obs._ this genus, of which only two or three recent species are known, resembles many species of venus and cytherea in general form; but differs in having lateral teeth, and in the palleal impressions which in all the veneres, &c. is sinuated. from lucina it may be known, not only by its oval form, but also by the muscular impressions, which, in lucina are produced into an elongated point; it will also be distinguished from tellina, by the want of a posterior fold in the valve, for which that genus is remarkable. c. fimbriata, fig. , is an inhabitant of the indian ocean. several fossil species are found in the recent formations, above the chalk, at grignon and hauteville. corbula. brug. (_a little basket._) _fam._ corbulacea, lam. conchacea, bl.--_descr._ inequivalve, sub-equilateral, transverse, gibbose, not gaping; cardinal tooth in each valve, conical, curved, prominent, inserting its extremity into a pit in the opposite hinge; cartilage attached to the tooth of the smaller valve, and the pit in the larger; muscular impressions, two in each valve, distant, rather irregular; palleal impression posteriorly angulated.--_obs._ the shells composing this genus were placed in mya by linnæus, but differ from the true myæ in having a sinus in the palleal impression, and a prominent ligamentiferous tooth in each valve, whereas the myæ have but one. the corbulæ are marine, some species inhabiting the british coasts. fossil species occur abundantly in green sand, london clay, crag, and corresponding formations. fig. . c. nucleus. corbulacea. (corbulées, lam.) a family of the order conchifera dimyaria, lam., containing the genera-- . corbula, with a prominent curved tooth. the fresh-water species has been separated under the name _potamomya_. fig. . . pandora. thin, pearly, no teeth. fig. . cordiform. (_cor_, a heart.) heart-shaped, a term applied generally to any shell which may be fancied to resemble a heart in shape, as isocardia, fig. , and cardium dionæum, fig. . coriaceous. (_corium_, leather.) of the substance of leather. _ex._, the integument into which the valves of chitones are inserted. coriocella. bl. the animal designated by this name is described by de blainville as being without any traces of shell, either internal or external. this must have arisen from the imperfection of the specimen described, probably deprived by accident of its shell. the testaceous appendage of the coriocella is now well known to naturalists. it is a milky white, transparent shell, shaped like sigaretus. cornea, and pisum, megerle. cyclas, lam. corneo-calcareous. a term used to express the mixture of horny and shelly matter which enters into the composition of some shells, aplysia, for instance. it is also applied to those opercula, which are horny on one side, and testaceous on the other, as that of turbo. corneus. horny. a species of patella has had the specific name corneus given to it, because its texture more nearly resembles that of a horn than that of a shell. the epidermis of fresh-water shells is of a similar composition. cornucopia. humph. lepas, linn. coronales. see coronular multivalves. coronated. (_corona_, a crown.) applied to shells when ornamented with a series of points, tubercles, &c., round the upper edges of the volutions. _ex._ conus nocturnus, fig. . coronaxis. one of the two genera into which swainson divides the genus conus, consisting of those species which have a row of tubercles on the upper edge of the whorls, an arrangement by which he would in many instances, not only separate between two individuals of the same species, but also between two parts of the same shell; for instances occur in which the earlier whorls are coronated, while the body whorl and the penultimate are perfectly plain. coronula. (_corona_, a crown, dim.) _order_, sessile cirripedes, lam. _fam._ balanidea, bl.--_descr._ six radiated valves, joined side by side in a circle, forming a depressed cone; internal structure of the valves, porous or chambered; thickened at the base; operculum consisting of four valves in pairs; imbedded horizontally in a cartilaginous substance.--_obs._ the shells composing this genus are found partly imbedded in the skin of whales, and the shells of tortoises, and are therefore destitute of the shelly foundation on which the balani and other coronular multivalves are supported. c. testudinaria, (chelonobia, leach,) fig. . c. balænarum, (cetopirus, ranz.) fig. . c. diadema, (diadema, ranz.) fig. . coronular multivalves are those which have their parietal valves joined together side by side in a circle, surrounding the body of the animal, so as to form a sort of coronet. this is the characteristic of the sessile cirripedes of lamarck's system, the balanidea of de blainville. corroded. (_corrodo_, eat away, consume.) the umbones, apices, and other thick parts of shells, are frequently worn away or consumed by the action of the element in which they exist. as the thickest parts of some shells are the most subject to this operation, it appears to the author to arise from the outer surface of the shell, being less under the influence of the animal juices than the other parts; and therefore, more exposed to the influence of the surrounding element. this, however, is not the case with respect to the nayades and other fresh-water shells; with these, corrosion does not take place until after the thick epidermis which covers them, becomes wounded by some means or other, and then the animal thickens its shell within as fast as it is corroded without. cortalus. montf. (conch. syst. . .) a genus of microscopic foraminifera, placed by de blainville in a division of the genus rotalites. costated. ribbed, as cardium angulatum, fig. . costellaria. a sub-genus of the genus tiara, sw. (mitra.) c. rigida. swainson, zool. ill. st series, pl. . cowry. a common name for shells of the genus cypræa. crania. (_cranium_, a skull.) _fam._ rudistes, lam. _order_, pallio-branchiata, bl.--_descr._ inequivalve, equilateral, irregular, sub-quadrate; upper valve patelliform, conical, with the umbo near the centre; lower valve attached by its outer surface; muscular impressions, in each valve; two large, posterior, distant; two small, near to each other, central. no hinge teeth; no ligament.--_obs._ this genus properly belongs to the brachiopoda, lam. it differs from orbicula in the mode of attachment, which in the latter, is by a byssus passing through the lower valve, and not by the valve itself. hipponyx has only two muscular impressions in each valve. the name of this genus is derived from the inner surface of the attached valve, which presents a remarkable resemblance to the facial portion of a human skull. this appearance is caused by the situation and elevated edges of the muscular impressions. fig. . coasts of britain and mediterranean. crassated. (_crassus_, thick.) used to express a thickness in the substance of a shell. _ex._ glycimeris, fig. . crassatella. lam. (_crassus_, thick.) _fam._ mactracea, lam. conchacea, bl.--_descr._ equivalve, inequilateral, close, thick, rounded anteriorly, rostrated posteriorly, with denticulated margins, smooth, or ribbed transversely; hinge with a triangular pit containing the cartilage, two anterior cardinal teeth, and a posterior depression in one valve; one anterior tooth and a slight anterior marginal elevation, and a posterior elevation in the other valve. muscular impressions distant, strongly marked. palleal impression not sinuated.--_obs._ the few recent species known are marine, several being brought from the coasts of new holland. fossil species are found in calcaire-grossier and london clay. the crassatella are known from the veneres, &c., by the ligamentary pit in the hinge, and from lutraria and mactra by the thickness and closeness of the shell. fig. , c. rostrata. crassina. lam. astarte, sow. crassipedes. lam. (_crassus_, thick; _pes_, foot.) the first section of the order conchifera dimyaria, lam. in this section the foot of the animal is thick, and the shell gapes considerably. it is divided into the families tubicolæ, pholadidæ, solenidæ, and myaria. fig. to . crassispira. sw. a genus separated from columbella, auct. for which mr. swainson quotes "pleurotoma bottæ, auct." crassispira fasciata, sw. lardn. cyclop. malac. p. . crenated. (_crena_, a notch.) applied to small notches, not sufficiently raised or defined, to be compared to teeth. _ex._ the hinge of iridina, fig. . crenatula. lam. _fam._ malleacea, lam. margaritacea, bl.--_descr._ compressed, foliated, irregular, sub-equivalve, inequilateral, oblique; umbones terminal; hinge linear, nearly straight, with a series of excavations, containing the cartilage, while the intervening ridges are covered with the ligament, properly so called. muscular impression oblong, indistinct.--_obs._ this genus is known from perna by the hinge, which in the latter is composed of a series of regular, straight, ligamentary grooves placed across it. in crenatula also there is no passage for the byssus, as in perna. c. mytiloides, fig. . coasts of the red sea. crenulated. finely crenated or notched. crepidula. lam. (_crepidula_, a little slipper.) _fam._ calyptracea, lam. and bl.--_descr._ oval, irregular, patelliform; apex lateral, incurved, or sub-spiral; external surface convex, smooth, ribbed, waved, or covered with spines; interior concave, smooth, with a flattish septum reaching nearly half across the cavity; epidermis light brown.--_obs._ the difference between this genus and calyptræa is that in the latter, the septum is more free from the sides of the shell, so that, instead of forming a regular plate, covering half the aperture, it assumes a variety of shapes, and in some is cup-shaped, in others forked, and in some forms a little angular shelf. indeed, the variations are so numerous that i think it would be better to throw the two genera into one, and then divide them into smaller groups. some species of calyptræa are farther removed from each other with respect to the characters of the septum and general form of the shell, than they are from the crepidulæ. fig. . mediterranean, north and south america, east and west indies, new south wales, &c. crepidulina. bl. cristellaria, lam. microscopic. creseis. ranz. _order_, pteropoda, lam.--_descr._ thin, fragile, transparent, pyramidal, pointed; with a dorsal ridge produced into a point at the edge of the aperture.--_obs._ the species found in the mediterranean is named c. spinifera (fig. ), from its resemblance to a thorn. creusia. leach. (_creux_, se. fr. a cavity.) _fam._ balanidea, bl. _order_, sessile cirripedes, lam.--_descr._ a depressed cone, consisting of four valves, supported upon, and jointed to, a cup-shaped cavity formed in the madrepores, in which it resides. aperture quadrilateral, closed by an operculum of four valves.--_obs._ this genus is distinguished from pyrgoma, which is supported on the edge of a similar cup-shaped cavity, by the paries being composed of four valves, whereas in pyrgoma, it consists of a single piece. fig. , c. gregaria. east indies. cricostomata. bl. the second family of asiphonibranchiata, bl. it is thus described: "shell equally (with the animal) variable in general form, but of which the aperture, always nearly round, is completely closed by the shelly or horny operculum; whorls few, and apex sublateral." this family agrees in some measure with the family turbinacea of lamarck, and with the genus turbo in the system of linnæus. it contains the genera pleurotomaria, delphinula, turritella, proto, scalaria, vermetus, siliquaria, magilus, valvata, cyclostoma, and paludina. crioceratites. a genus composed of species of ammonites, with disconnected whorls. c. duvallii, fig. . criopus. poli. crania, auct. cristacea. lam. the third family of polythalamous cephalopoda, lam. this family is described as including shells of the following characters:--"multilocular, flattened, nearly reniform; the chambers gradually increasing in length, as they approach the outer arched margin, and appearing to revolve round an eccentric, more or less marginal axis. the cristacea contain the genera renulina, cristellaria, and orbiculina." cristacea. bl. the third family of polythalamia, bl. containing the genera crepidulina, (cristellaria, lam.) oreas and linthuris. cristaria. schum. dipsas plicatus, leach. anodon tuberculatus, fer. cristellaria. lam. crepidulina, bl. _fam._ cristacea, lam. and bl.--_descr._ semidiscoidal, chambered; whorls contiguous, enlarging progressively; spire eccentric, sublateral; septa imperforate. microscopic. crypta. humph. crepidula, lam. cryptella. webb. ([greek: kruptô], to conceal.) testacellus ambiguus of ferrusac. published in sowerby's genera of shells as parmacella calyculata.--_descr._ a small patelliform shell, with a very short papillary spire; and the aperture irregularly expanded. fig. . canary islands. cryptoconchus. bl. a genus composed of species of chiton, the valves of which are covered by the integument, as chiton porosus of burrows. ch. amiculatus of pallas. cryptodibranchiata. bl. the first order of the class cephalophora, bl. containing families of molluscous animals destitute of shells. cryptostoma. bl. differs from sigaretus, lam. principally in the soft parts of the animal. de blainville remarks that he is acquainted with only two species (from the indies), which he can with decision refer to the genus, but he thinks that many of the lamarckian sigareti may very probably be found to belong to it, as soon as the soft parts shall be known. the species which he figures is cryptostoma leachii. (manuel de malacologie, pl. . fig. .) ctenoconcha. gray. described as having many characters in common with the solens, the teeth like nucula, but the cartilage entirely external. solenella, sow.? cucullÆa. lam. (_cucullus_, a hood.) _fam._ arcacea, lam.--_descr._ sub-quadrate, nearly equivalve, sub-equilateral, deep; hinge rectilinear, with a series of angular teeth, small near the umbones, larger and more oblique towards the extremities; umbones separated by a flat external area, on which the ligament is spread. anterior muscular impression produced into a sharp-edged plate or ledge, projecting from the side of the shell. posterior muscular impression flat and indistinct.--_obs._ this genus very much resembles arca in general form, but differs in the oblique, lengthened character of the remote teeth, and in the singularly prominent edge of the muscular impression. china. fig. , c. auriculifera. cucumis. klein. marginella, auct. cultellus. species of lutraria, lam. which have the umbones placed near the extremity of the shell. _ex._ l. solenoides, fig. . cuma. humph. fusus and fasciolaria, lam. cumingia. sow. _fam._ mactracea, lam.--_descr._ equivalve, inequilateral, transverse, rounded anteriorly, subrostrated posteriorly. hinge with a central spoon-shaped cavity in each valve, containing the cartilage; a very small anterior cardinal tooth in each valve; two lateral teeth in one valve, none in the other: muscular impressions two in each valve, distant; palleal impression with a very large posterior sinus.--_obs._ the species known at present are found in sand, in the fissures of rocks in tropical climates. they resemble erycina in general form and character, but differ in having the internal cartilage placed in a prominent spoon-shaped process, while that of erycina is contained in a hollow which sinks under the umbones. this genus should be placed near amphidesma. cumingia mutica, fig. . cuneiform. (_cuneus_, a wedge.) wedge-shaped, as donax, fig. . cuneus. megerle. venus meroe, linn. and similar species. cunicula. sw. a sub-genus of uniones, thus described:--"ovate, oblong; bosses thick, but depressed; cardinal teeth moderate. c. planulata, patula, rubiginosa, secura, purpurascens." curved. arched or bent. _ex._ dentalium, fig. . curvula. rafinesque. a fossil imperfectly described as differing from pinna, in being inequivalve. cuvieria. ranz. (baron cuvier.) _class_, pteropoda, lam.--_descr._ thin, transparent, glassy, cylindrical, rounded and inflated at the closed extremity, compressed towards the opening, so as to render it oval. this genus differs from vaginula in being rounded, instead of pointed, at the lower extremity. mediterranean. fig. , c. columella. cyclas. brug. _fam._ conques fluviatiles, lam. conchacea, bl.--_descr._ orbicular, thin, subovate, ventricose, sub-equilateral, equivalve; cardinal teeth minute, one more or less complicated in the left valve, two diverging in the right; lateral teeth elongated, compressed, laminar, acute, doubled in the left valve; ligament external; epidermis thin, horny.--_obs._ the cyclades are viviparous, and abound in ditches, ponds, slow streams, &c. in europe and north america. the genus pisidium has been separated on account of a difference in the animal, and may be known from cyclas by being less equilateral, and the anterior side being the longest. fig. , c. rivicola. cyclobranchiata. bl. the third order of the second section of paracephalophora monoica, bl. containing no genera of testaceous mollusca. cyclocantha. sw. a genus of "trochidæ," consisting of turbo stellaris and t. calcar, and corresponding with the genus calcar, montf. cyclonassa. sw. a genus of "nassinæ," sw. consisting of nassa neritoidea, and corresponding with the genus cyclops, montf. cyclophorus. montf. a generic name proposed for those species of cyclostoma, auct. which have an umbilicus. c. involvulus, fig. , would be the type of this genus. cyclops. montf. nassa neritoidea, auct. fig. . cyclostoma. auct. ([greek: kuklos], _cyclos_, round; [greek: stoma], _stoma_, mouth.) _fam._ colimacea, lam. cricostomata, bl. a genus of land shells varying in shape from that of pupa to that of a flat orb; the aperture is generally circular and the peritreme uninterrupted, thickened and sometimes reflected, the operculum is shelly and spiral. two other genera of land shells are provided with opercula, and consequently might be confounded with this genus. in helicina, the operculum is concentric and the peritreme is not continuous; while in the small genus hitherto almost unknown of pupina, the peritreme is not continuous and there is a glassy enamel over the whole of the external surface. in the plates we have represented, c. ferrugineum, fig. ; c. involvulus, fig. . cyclotus. guild. a sub-genus of cyclostoma, consisting of those species which are discoidal, as c. planorbulum. fig. . cylinder. montf. conus textile, auct. (fig. ) and other species having a cylindrical form. cylindrella. sw. a genus of the family "ovulinæ," sw. composed of cylindrical species of ovulum? the wood-cut illustrating this genus has the appearance of a bulla. cylindrical. ([greek: kulindros], a cylinder.) this like other mathematical terms is used with great latitude by conchologists, and applied to any shell the sides of which are nearly parallel, with the extremities either rounded, flat, or conical. _ex._ oliva, fig. . cyllene. gray. _fam._ purpurifera, lam.--_descr._ oval, thick, with a short acute spire; an oval aperture terminating anteriorly in a slight emargination, posteriorly in a short canal; a fold at the lower end of the body whorl; outer lip thick, striated within; angle of the whorls tuberculated.--_obs._ this genus of small marine shells resembles voluta in general character, but differs in having a smooth columella without folds. recent, pacific ocean; fosil, london clay. fig. . cymba. brod. (_cymba_, a boat or skiff.) _fam._ columellaria, lam.--_descr._ smooth, ventricose, with a very short, mammillated, rude spire; and a very large, wide aperture, terminated anteriorly in a deep emargination; posteriorly in a flat ledge, which separates the outer lip from the body whorl; columella with three or four oblique, laminar, projecting folds, terminating in a point; outer lip thin, with its edge sharp; epidermis smooth, brown, covered partly or entirely by the glassy enamel, which, commencing with the outer lip, spreads over the body of the shell.--_obs._ these very elegant shells, found in africa, are distinguished from the true volutes by the shapeless, mammillated apex of the short spire, by the large size of the aperture, and by the horizontal ledge which separates the outer lip from the body whorl. the genus melo, also separated by mr. broderip from the volutes, agrees with cymba in some respects, but differs in the regularity of the spire. fig. , c. porcina. cymbiola. sw. the generic name for a group of volutes, described as "armed with spinous tubercules, sometimes smooth, but never ribbed; spiral whorls gradually diminishing in size, but not distorted; apex thick and obtuse; pillar with four plaits." mr. swainson remarks that this genus is chiefly distinguished by the obtuse, but not irregular spire. the typical species are stated to be v. rutila and v. vespertilio, fig. . tropical. cymbulia. (dim. from _cymba_.) _fam._ pteropoda, lam. an extremely light, cartilaginous covering of a molluscous animal, so named from its similarity in shape to a boat. we mention it here on account of its similarity to the shelly or glassy covering of other pteropods, to which, although membranaceous, it is evidently analogous. the cymbuliæ are found in the mediterranean. cyprÆa. auct. _fam._ enroulées, lam. angyostomata, bl.--_descr._ oval or oblong, ventricose, convolute, covered by an enamel, generally smooth and shining. spire short, nearly hid. aperture long, narrow, terminating in a short canal at both extremities. outer lip dentated, thickened, inflected. inner lip dentated, thickened, reflected over part of the body whorl.--_obs._ these shells are so distinguished by the two rows of teeth arranged on each side of the aperture; the thickened front formed by the inner and outer lips; and the enamel deposited over the back of the shell from the mantle of the animal which envelopes it, that there is no danger of confounding them with any other genus, except in a young state. before they have arrived at the full growth, the front is not thickened, and the outer lip is thin, not inflected, nor are the teeth formed. in this state the shell resembles, in some degree, an oliva. some species are striated, ribbed, or tuberculated, but the generality are smooth. most species belong to tropical climates, only one to great britain. the c. moneta is current as money in some parts of africa, and many species are worn as ornaments by the south sea islanders. the colouring in most species is exceedingly rich, and arranged in every variety of spots, patches, rings, lines, bands and clouds. the species most esteemed by collectors are c. mappa, c. testudinaria, c. pustulata, c. aurora, c. princeps, of which only two specimens are known, c. leucodon, &c. see also cypræovulum, trivea and luponia. the fossil species are principally from the calc-grossier, the london clay, crag, &c. fig. to . the latest revision of this genus has been effected by mr. g. b. sowerby, sen., who has published a complete catalogue in his son's conchological illustrations. this catalogue enumerates species, the whole of which are figured in parts to , to of the above mentioned work. cyprÆcassis. stutch. (cypræa and cassis.)--_descr._ shell, when young, striated, reticulated, or tuberculated; outer lip simple: when mature, outer lip involute and toothed; columellar lip also toothed; aperture straight, anteriorly terminated by a recurved canal, posteriorly by a shallow channel. animal with the mantle bilobed; operculum none.--_obs._ the reasons given for separating this genus from cassis, are, st, that the shells of the latter have an operculum, while those of the proposed genus have none. nd, that the cypræcassides do not form a complete, thickened lip, before the full period of their growth, like the cassides. rd, that the cypræcassides have no epidermis. the species mentioned as probably belonging to cypræcassis are c. rufa, the type; c. coarctata, and c. testiculus, auct. the establishment of this genus has been opposed on the ground that indications of epidermis are discoverable in some specimens of c. rufa; that some specimens of the same species and testiculus have been examined, and found to have formed slightly thickened and dentulated outer lips at very early periods of growth, while many of the other cassides are destitute of varices, and that an operculum of c. coarctata was brought to this country by mr. cuming. it is probable, however, that an increased knowledge of facts might go far to establish the separation. c. testiculus, fig. . cyprÆadia. sw. a genus of the family "cypræidæ," sw. thus described:--"cypræform; the base contracted; the body whorl not flattened beneath; shell cancellated; aperture of equal breadth throughout; a few thickened, short teeth on the pillar; lip at the base, which is not internally concave. c. cancellata, sw. fossil only, differing from trivea in its contracted base, in the inequality of its aperture, and the equal convexity of the inner lip within." (sw. lardn. cyclop. malac. p. .) cyprædia, fig. . cyprÆla. sw. a genus formed for the reception of ovulum verrucosum, auct. which has a circular depression at each extremity. it is the same as the genus calpurnus of de montfort. ovulum verrucosum, fig. . cyprÆovulum. gray. a genus of cypræidæ thus described, "shell like a cowry, but front end of columella covered with regular cross-ribs, like the rest of the base, internally produced into an acute toothed ridge. shell pear-shaped, cross-ridged." c. capense, fig. . south africa. cypricardia. lam. _fam._ cardiacea, lam.--_descr._ equivalve, inequilateral, subquadrate, transversely elongated, with the anterior side very short; hinge with three cardinal teeth and one remote lateral tooth in each valve; muscular impressions two in each valve; ligament external.--_obs._ this genus is distinguished from cardita by the three cardinal teeth. the mollusca of this genus are marine. c. angulata, fig. . pacific ocean. cyprina. lam. _fam._ "conques marines," or marine conchacea.--_descr._ equivalve, inequilateral, sub-orbicular; umbones curved obliquely; hinge with three diverging cardinal and one remote lateral teeth in each valve; ligament external; muscular impressions two in each valve; palleal impression having a slight posterior sinus; epidermis thick, rough brown.--_obs._ the cyprinæ belong to the northern hemisphere. the recent species are not numerous. fossil species are found in the tertiary deposits. cyprina may be known from venus by the remote lateral tooth and the thick epidermis. c. vulgaris, fig. . cyrena. auct. _fam._ fluviatile conchaceæ, lam. conchacea, bl--_descr._ suborbicular, equivalve, inequilateral, ventricose, corroded at the umbones, thick, covered with a thick epidermis; hinge with three cardinal and two remote lateral teeth in each valve. muscular impressions two in each valve; palleal impression not sinuated.--_obs._ this genus is distinguished from venus, cytherea and cyprina, by having two remote lateral teeth; and from cyclas by the thickness of the shell. this genus is mostly fluviatile; the recent species are tropical, and the fossil are found in the newest formations. fig. , c. fuscata. cyrenella. desh. see cyrenoides. cyrenoides. joannis. cyrenella, desh. _fam._ conques fluviatiles, lam.--_descr._ equivalve, subequilateral, ventricose, thin, covered with a reddish brown epidermis, corroded at the umbones, with a slight posterior fold. hinge thin, with three diverging cardinal teeth in each valve, and a very slight posterior fold in the right valve. ligament not very tumid.--_obs._ this fresh-water shell differs from cyclas and cyrena in the want of lateral teeth, and from the latter in the thinness of the shell. fig. . cyrtia. dalman. ([greek: kurtos], curtos, gibbose.) _fam._ brachiopoda, lam.--_descr._ "hinge rectilinear; with the back elevated into a semicone or half-pyramid, the cardinal side perpendicularly _plane_."--_obs._ this genus of fossil brachiopoda forms part of the genus spirifer, sow. c. exporrecta, (anomites exporrecta, nonnull.) fig. . cytherea. lam. _fam._ "conques marines," lam.--_descr._ equivalve, inæquilateral, oval, lenticular, or sub-trigonal; hinge with two or more short, diverging cardinal teeth, and one anterior approximate lateral tooth in each valve.--_obs._ the cythereæ are distinguished from the veneres by the lateral tooth. c. meretrix, fig. , and , _a. b. c. d._ dactylus. humph. marginella, auct. daracia. gray. a subgenus of pyrgoma, including a species which is remarkable for the irregularity of its form. it grows upon a species of monticularia, and the margin takes the shape of the lobes by which it is surrounded. the aperture is large, and completely closed by the operculum. daracia (pyrgoma) monticulariæ, fig. , . date. a common name given to shells of the genus pholas, on account of their cylindrical form and consequent resemblance to the fruit. for the same reason the name pholas dactylus has been given by naturalists to the species which we represent, fig. . dead shell. a term used among collectors to signify that the shell has been exposed on the sea-shore after the animal has ceased to live. a shell in this condition is worn down by attrition, and loses its beauty and brilliancy of colouring by being subject to the action of salt water. a dead shell may be known by a certain hoary whiteness spread over its surface. decacera. bl. the second family of the order cryptodibranchiata, bl. containing the genera calmar and sepia, which have no shells. decadopecten. rüppell. pecten _plica_, linn. fig. , having a plicated hinge. decollated. (_decollari_, to be beheaded.) the apex or nucleus of some shells being composed of a more fragile substance than the rest, has a tendency to fall off. the reason of this probably is that the animal withdrawing from that part, leaves it unprotected. when it falls off, the hole is stopped up by a septum filling the cavity of the volution, so as to exclude the air: the shell is then said to be decollated. _ex._ bulinus decollatus, fig. . decussated. intersected by striæ crossing each other. _ex._ rissoa, fig. . delphinula. montf. (_delphinus_, a dolphin.) _fam._ scalariens, lam. cricostomata, bl.--_descr._ orbicular, depressed, thick, rugose; whorls few, angulated, branched at the angles; aperture pearly, rounded or sub-quadrate; peritreme continuous, thickened; operculum horny, composed of numerous whorls.--_obs._ several fossil species are found in the tertiary deposits. d. laciniata, fig. . recent species belong to tropical climates. delthyris. dalman. _fam._ brachiopoda, lam.--_descr._ hinge more or less rounded, with distant umbones; both valves convex; with the umbo of the largest rostrated and deltoid, with a hollow. this genus forms part of the genus spirifer, sow. fig. . d. plycotes, dalman. deltoid. ([greek: d], _delta_.) triangular. dendostrea. sw. ([greek: dendron], _dendron_, tree; [greek: ostreon], _ostreon_, oyster.) ostrea _crista-galli_, and other species which are attached to stems of sea-weed and corallines, by means of arms thrown out from the inner surface of the lower valve. fig. , ostrea folium. dentalium. auct. (_dens_, a tooth.) _fam._ maldania, lam. _order_, cirrobranchiata, bl.--_descr._ tubular, arched, increasing in size towards the anterior extremity, open at both ends; small aperture sometimes having a lateral fissure; large aperture round; external surface ribbed, striated or smooth.--_obs._ the well known shells composing this genus are shaped very much like an elephant's tusk, and are not liable to be confounded with any other genus. the fossil species are sometimes termed dentalithes, from _dens_, a tooth, and _lithos_, a stone. the dentalia, being true molluscs, are not rightly placed among the annelides. fig. , d. octogonum. found on sandy shores in most climates. dentated. having teeth or raised points. denticulated. (denticulatus, lat.) having little teeth or raised points. depressed. flattened, pressed down, as the spires of some shells. dextral spiral shells. place the point of a spiral shell towards the eye, with its mouth downwards; if, as in most instances, the aperture be on the right side of the axis, it is a _dextral_ shell, if otherwise, it is _sinistral_ or _reversed_. balea (fig. ), and clausilia (fig. ), are examples of reversed shells. dextral valve. take a bivalve shell closed, place it before the eye, with the umbones uppermost, and the posterior side, which may be known by the ligament towards the observer, whose right side will then correspond with the right valve of the shell. diadema. ranz. coronula diadema, auct. fig. . dianchora. sow. _fam._ pectinides, lam. _order_, palliobranchiata, bl.--_descr._ inequivalve, attached, oblique, subtriangular; attached valve, having an opening in the place of the umbo; the other valve auriculated, with an obtuse umbo; hinge without teeth.--_obs._ the green sand fossils contained in this genus differ from plagiostoma in being attached. fig. , d. striata. diaphanous. ([greek: dia], _dia_, through; [greek: phainô], _phaino_, to shine.) transparent. diaphragm, ([greek: diaphragma], a partition.) this term is applied to the septa, by which the chambers of multilocular and other shells are divided from each other. diceras. lam. ([greek: dis], _dis_, double; [greek: keras], _ceras_, horn.) _fam._ chamacea, bl. and lam.--_descr._ inequilateral, inequivalve, attached by the point of the umbo of the larger valve; umbones prominent, spirally twisted and grooved; hinge with one large thick tooth in the larger valve; muscular impressions, two in each valve.--_obs._ the prominent spiral umbones, which give rise to the name of this genus, with the circumstance of its being attached by the point of one of them, is sufficient to distinguish it from any other, although it appears to approach isocardia in some characters. in others it will be found still more nearly to resemble chama. in fact, from being attached and irregular, the shells composing this genus have been considered as chamæ with produced umbones. the singular fossil shells composing this genus, are found in granular limestone, near geneva and in normandy. fig. , d. perversum. didonta. schum. saxicava. auct. diffuse. (_diffundo_, to spread out, to dilate.) a term applied to the aperture of a univalve shell, when it is spread out or widened into a flat surface, or digitations. _alated_ is another term used to express the same character. thus, the shells belonging to the family of alatæ, in the system of lamarck, are _diffuse_ in the outer lip. fig. to . digitated. (_digitus_, finger.) branched out in long points, as ricinula, fig. . dilated. expanded, spread. this term has the same application as diffuse and alated, explained above. the outer lip of rostellaria columbaria, fig. (hippochrenes, montf.), will serve as an example. dimorphina. d'orb. a genus of microscopic foraminifera. dimyaria. ([greek: dis], _dis_, double; [greek: muon], _myon_, muscle.) the first order of conchifera, lam. including those molluscs which have two adductor muscles, and consequently two muscular impressions in each valve. the conchifera dimyaria are divided into crassipedes, tenuipedes, lamellipedes, and ambiguæ, fig. to . dioica. bl. the first division of the class paracephalophora, bl. it is divided into the orders siphonobranchiata and asiphonibranchiata, bl. diplodon. spix. hyria syrmatophora, lam. fig. , and unio multistriatus, lea, are doubtfully quoted by lea as belonging to this apparently ill-defined genus of nayades. dipsas. leach. a genus or sub-genus of nayades, the distinctive character of which is "having a linear tooth under the dorsal edge." d. plicatus, fig. . discina. lam. orbicula, auct. discodoma. sw. a sub-genus of lucerninæ, sw. (helix), thus described, "teeth none; aperture angulated; the inner lip nearly obsolete; the outer only slightly thickened; margin carinated." discoidal. (_discus_, a circular plane.) a spiral shell is said to be discoidal, when the whorls are so horizontally convolute as to form a flattened spire. _ex._ planorbis, fig. . orbulites discus, fig. . discolites. montf. a genus of microscopic foraminifera. discontinuous. interrupted. _ex._ the siphon of nautilus is discontinuous, i. e. its termination in one chamber does not reach to its commencement in the next. the varices of triton, occurring in different parts of the whorls, do not form the continuous ridges which characterize the generality of the ranellæ. discorbites. lam. a genus of microscopic foraminifera. distant. the teeth on the hinge of a bivalve shell are said to be distant when they are remote from the umbones. divaricated. diverging, meeting in a point, as the teeth on the hinge of placuna, fig. . dolabella. lam. (dim. from _dolabra_, a hatchet.) _fam._ aplysiacea, lam. and bl.--_descr._ hatchet-shaped, arched, covered with a horny epidermis; posteriorly attenuated, thickened, sub-spiral, anteriorly plane, broad, thin; posterior margin reflected.--_obs._ the two or three species of dolabella known are inhabitants of the indian ocean. they were placed by linnæus in his very convenient genus bulla, under the name b. dubia. fig. , dolabella rumphii. dolium. d'argenville. (_a tun._) _fam._ purpurifera, lam. entomostomata, bl.--_descr._ thin, ventricose, oval, or globular, with a short spire; large aperture terminating in a reflected canal, and spirally ribbed or grooved external surface; outer lip crenated; inner lip reflected over part of the body whorl, which terminates in a tumid varix; epidermis light, horny. mediterranean and east indian.--_obs._ this genus is distinguished from cassis by the outer lip, which is not reflected. the species which are not so rotund as the others, as d. perdix, auct. have been separated under the name perdix, as generic. fig. , dolium maculatum. donax. auct. _fam._ nymphacea, lam. conchacea, bl.--_descr._ equivalve, inequilateral, trigonal, with the anterior side short, straight, plane; the posterior side elongated, drawn to a narrow, rounded termination; hinge with two cardinal teeth in one valve, one in the other, and one or two, more or less remote lateral teeth; ligament external; muscular impressions two in each valve; palleal impression sinuated posteriorly.--_obs._ the capsæ have not the crenated margins, the short anterior side, and the distinct lateral teeth, which characterize the donaces. some species of erycina resemble donax in general form, but are at once distinguished by the ligamentary pit in the hinge. sandy shores in all climates. fig. , d. cuneatus. dorsal. a dorsal shell is one placed upon the back of the animal. the dorsal margin of a bivalve shell is that on which the hinge is placed; the opposite margins are termed ventral. the dorsal surface of a spiral univalve is that which is seen when the aperture is turned from the observer. the dorsal valve is the uppermost in brachiopodous bivalves. the dorsal part of a symmetrical convolute univalve, such as the nautilus and ammonite is that part of the whorls which is at the greatest distance from the spire, that is, the outer part of the whorls. thus the situation of the siphon is said to be dorsal when it pierces the septum near the outer edge of the whorls. the dorsal part of symmetrical conical univalves, such as patella, is the upper part, on which the apex is placed. dorsalia. lam. (_dorsum_, the back.) the first family of the order annelides sedentaria, lam. containing the genera arenicola, not a shell, and siliquaria, fig. , which is now considered as a true mollusc, and placed next to vermetus. dosina. schum. venus verrucosa, casina, and similar species. fig. , a. dreissina. mytilus polymorphus. auct. fig. . this genus differs from mytilus principally in the characters of the animal. the shell is characterized by a small septiform plate under the hinge within. fluviatile, europe and africa. eburna. lam. (_eburneus_, ivory.) _fam._ purpurifera, lam. entomostomata, bl.--_descr._ oval, thick, smooth, turrited, umbilicated; spire angulated, acute, nearly as long as the aperture; aperture oval, terminating anteriorly in a canal, posteriorly in a groove; outer lip slightly thickened with an anterior notch, which terminates in a spiral fold surrounding the body whorl; umbilicus generally covered by the thickened columellar lip.--_obs._ the beautiful shells called ivory shells, which originally constituted part of this genus, are now placed in the genus ancillaria by authors. they differ from the present genus eburna, in having the sutures of the spire covered with a polished enamel. (a. glabrata, fig. .) the eburnæ resemble in some respects the genus buccinum, but a glance at the figure will enable the reader to distinguish a true eburna from all other shells. fig. is eburna zeylanica. a catalogue of species is given in part of the conchological illustrations published by the author, accompanied by figures of several species. echidnis. montf. described as a straight, chambered, annulated, fossil shell, computed from the extremely gradual increase in diameter of the fragments to be at least sixteen feet long. found in marble from the pyrenees. echinella. sw. a sub-genus of monodonta. sw. malac. page . effuse. (_effundo_, to pour out.) the aperture of an univalve shell is said to be effuse when there is a notch in the margin which would suffer a liquid to escape, and thus prevent it being filled to the brim. egeon. montf. a genus of microscopic foraminifera. egeria. lea. (contrib. to geol. p. , pl. .) a genus of fossil bivalves, described as very variable in form, with or without lateral teeth, sometimes a crenated margin, &c. the only certain characters appear to be that they have two diverging cardinal teeth in each valve, one of which is bifid; and an external ligament. lea states that the egeriæ should be placed between the sanguinolariæ and the psammobiæ, which two latter genera have been united by sowerby. fig. , e. triangulata, from the tertiary formation of alabama. elenchus. humph. a genus composed of trochus iris, auct. and other similarly formed species. it is the same as cantharidus of montfort. elephant's tusk. the common name given by dealers to shells of the genus dentalium. _ex._ d. octogonum, fig. . elevated. a term which is applied by some conchological writers to the spire of an univalve shell when it consists of numerous whorls drawn out into a telescopic form. other authors use the term _elongated_, or the more simple one '_long_,' to express the degree of elevation. elisma. leach. a sub-genus of bulinus. b. acutus, auct. gray, turton, p. . ellipsolithes. montf. ([greek: elleipsis], _ellipsis_, oval; [greek: lithos,] _lithos_, stone.) a genus composed of ammonites, which instead of being regularly orbicular, take an elliptical or oval form. this character appears to be accidental, as some individuals of the same species, both of nautilus and ammonites, are round, while others are compressed into an oval form. ellipsostomata. bl. ([greek: elleipsis], _ellipsis_, oval; [greek: stôma], _mouth_.) the third family of the class asiphonibranchiata, bl. the shells of this family are described as of various forms, generally smooth; the aperture longitudinally or transversely oval, completely closed by a horny or shelly operculum. this family contains the genera rissoa, phasianella, ampullaria, helicina, and pleuroceras. elliptical. ([greek: elleipsis], _ellipsis_.) oval. applied to any shell or part of a shell, having that form. elmineus. leach. _order_, sessile cirripedes, lam.--_descr._ four unequal valves, arranged circularly side by side, forming a quadrate cone; aperture large, sub-quadrate, irregular; operculum composed of four valves, in pairs.--_obs._ this genus differs from conia in the structure of the shell, the latter being porous. fig. , elmineus leachii. elphidium. montf. (conch. syst. t. . p. .) a genus of microscopic foraminifera. emarginated. (_e_, out; _margo_, border.) notched or hollowed out. applied to the edges or margins of shells, when instead of being level they are hollowed out, as the outer lip of oliva, fig. , at the base, and the ventral margins of some bivalves. emarginula. lam. (_e_, out; _margo_, border.) _fam._ calyptracea, lam. branchifera, bl.--_descr._ patelliform, oblong or oval; anterior margin notched or emarginated; apex posteriorly inclined; muscular impressions wide.--_obs._ emarginula elongata, of some authors, parmophorus of de blainville is commonly called the duck's bill limpet, from its shape. the emarginulæ may be known from patellæ and other neighbouring genera, by the notch or slit in the anterior edge. in the genus rimula, defr. fig. , this slit is near the apex, and does not reach the margin. recent species occur in all climates, but are not numerous. fossil species are still more rare, occurring in the calc-grossièr, crag and oolite. e. fissurata, fig. . ena. leach. a sub-genus of bulinus. b. lackhamensis. mont. endosiphonites. a genus composed of ammonites, having the siphon close to the body whorl, fig. . endotoma. rafinesque. a genus of microscopic foraminifera. enroulees. lam. see convolutÆ. ensatella. sw. a genus consisting of solen ensis, auct. fig. , and other species similarly curved. _genus_ ensis, schum. ensis. schum. solen ensis, auct. and similar species. entalis. defr. dentalium duplicatum, bl. pharetrium, könig. this genus is described as a small tube, within a larger one, the smaller extremity of the inner tube projecting beyond that of the outer one. deshayes, who describes this genus, expresses a conviction that the soft parts of the animal must be entirely different from those of the animal of dentalium. the genus pharetrium, as described by könig in his "icones fossilium sectiles," is evidently identical with entalis. it is placed by him in the family of pteropoda, but being a fossil shell, there is some difficulty in finding its place in the system. see plates, fig. . entellites. fischer. a genus composed of species of terebratula, spirifer, and productus, auct. having the hinge large and the umbones short. orthis? dalman. entire. (integra.) not interrupted, not emarginated. the peritrême of a univalve shell is said to be entire when not interrupted by canals or by the body whorl. _ex._ cyclostoma, fig. . the palleal impression is entire, when continued without interruption, or without a sinus. entomostomata. bl. the second family of the order siphonibranchiata, bl. the shells of this family are described as differing but little from those contained in the family of siphonostomata of the same author, both with regard to the soft parts, and their testaceous covering. this family partly answers to the purpuriferæ in the system of lamarck, and contains the genera subula, cerithium, melanopsis, planaxis, terebra, eburna, buccinum, harpa, dolium, cassidaria, cassis, ricinula, cancellaria, purpura, concholepas. eolides. montf. a genus of microscopic foraminifera. epidermis. ([greek: epi], _epi_, over or upon; [greek: derma], _derma_, skin.) the fibrous, horny, external coating of shells, called by the french, "_drap marin_," or marine cloth. lamarck objects to the name epidermis because he does not consider the substance as answering to the cuticle or scarf skin of the human body, but more analogous to the nails and hair. gray calls it the periostracum, from the membranous skin covering the bones of quadrupeds. epiphragm. the membranaceous or calcareous substance by which some species of molluscs close the aperture of the shell, when they retire within it to hibernate. when the animal wishes to come forth from his hiding-place, again to breathe the air, the edges of the epiphragm are detached by a chemical process, so that it drops off. the name hibernaculum has also been given to this covering. it must not be confounded with the operculum, which is a permanent portion of the shell, and is used as a door, fitted to the foot of the animal and moved at will to open or close the aperture of the shell, whereas the epiphragm is produced for the occasion from a mucous secretion of the animal and dissolved at the edges when no longer wanted, when it drops off. epistyla. sw. a subgenus of the genus helix. e. conical. sw. helix epistylium, fig. . eponides. montf. a genus of microscopic foraminifera. equilateral. (Æquus, equal; latus, side.) equal-sided. a term applied to bivalve shells, when a line drawn down perpendicularly from the apex would divide the shell into two equal parts. _ex._ pectunculus pilosus, fig. . equivalve. (Æquus, equal; _valva_, a valve.) a term applied to a bivalve shell when the valves are equal to each other in dimensions. erato. risso. _fam._ convolutæ, lam.--_descr._ ovate, more or less angulated, smooth or granulated, with a dorsal scar; spire short; aperture large, angulated, emarginated; columella slightly crenated; outer lip reflected, denticulated on the inner edge. suture of the whorls covered with enamel.--_obs._ this genus of shells resembles marginella in form, but has no folds on the columella. having a scar or groove down the back it may be considered intermediate between marginella and cypræa. fig. , e. maugeriæ. in the author's conchological illustrations, seven species are enumerated and figured. eruca. sw. a subgenus of clausilia. sw. malac. p. . ervilia. turt. a genus described as "oval, equivalve, equilateral, closed. hinge with a single erect tooth closing between two small diverging ones in the opposite valve: lateral teeth none. ligament internal. e. nitens. turt. mya. nitens, auct." erycina. lam. _fam._ mactracea, lam. conchacea, bl.--_descr._ ovate or triangular, transverse, equivalve, inequilateral, smooth; hinge with a ligamentary pit, two diverging cardinal and two lateral teeth in each valve; muscular impressions two in each valve; palleal impressions sinuated. east and west indies and mediterranean.--_obs._ this genus is distinguished from _mactra_ and _lutraria_ by the cardinal teeth being placed one on each side of the ligamentiferous pit; whereas in the last named genera they are both placed on the anterior side. fig. , e. plebeja. erythrÆa. the ancient name for cyprÆa. escutcheon. the impression on the posterior dorsal margin of some bivalve shells. that on the anterior margin is named the lunule. the escutcheon is pointed out by the letter _e_ in some of the figures of cythereæ. fig. , _a. b. c._ etheria. lam. (_Æther_, air.) fam. chamacea, lam. and bl.--_descr._ irregular, inequivalve, inequilateral, foliaceous, pearly within, covered by an olive green epidermis without; hinge callous, undulated, destitute of teeth; ligament partly external, partly internal, passing through the hinge on a somewhat raised, callous area in the lower valve. muscular impressions elongated, two in each valve, united by a slender palleal impression. rivers of africa.--_obs._ the irregular, unequal air-bubbles of the inner surface, whence this genus derives its name, are very brilliant in some species, and atone, in some measure, for the rugged ugliness of the exterior. in its irregular form, foliated structure, and toothless hinge, it resembles ostrea, from which it differs in having two muscular impressions. fig. , e. semilunata. eulima. risso. _fam._ scalariens, lam.--_descr._ elongated, smooth, pyramidal; spire long, composed of numerous whorls; apex acute, slightly tortuous; aperture oval, rounded anteriorly, acute at the posterior union with the body whorl; outer lip slightly thickened; columella smooth. fig. , e. labiosa, fig. , e. splendidula. a complete illustrated monograph of this genus of pretty shining little shells, consisting of known species, is given in parts and of the conchological illustrations by the author. euomphalus. sow. _fam._ scalariens, lam.--_descr._ orbicular, planorbular spire, with three or four volutions, imbricated above; smooth below; aperture of a round polygonal form; umbilicus large, penetrating to the apex of the shell.--_obs._ this genus of fossils very nearly resembles delphinula. the main difference appears to be that the whorls do not increase so rapidly in size in the former as in the latter. fossil, in the carboniferous limestone. fig. . exogyra. sow. a genus of fossil bivalves, resembling chama in shape and ostræa in structure, having but one muscular impression in each valve. fig. . exserted. standing out, protruding. external. an external shell is one which contains the animal, and is not covered by the mantle. fasciated. (_fascia_, a band.) banded or striped. ex. carocolla marginata, fig. . fasciculated. (from fasciculum.) a little bunch of hairs or bristles against each end of each valve, characterizes some species of the genus chiton, which are termed fasciculated species. fasciolaria. lam. _fam._ canalifera, lam. siphonostomata, bl.--_descr._ elongated, fusiform, ventricose; spire conical, consisting of few rounded or angulated whorls; aperture wide, terminating in a long straight open canal: columella lip with several oblique folds, the lower of which is larger than the rest; operculum horny, pyriform.--_obs._ this genus is known from fusus by the folds on the columella; from turbinella, by their obliquity and the last being larger than the rest. fig. , f. trapezium. east and west indies and australia. faunus. montf. melanopsis, auct. ferrugineous. of an iron rust colour. ferussina. grateloup. strophostoma, deshayes. fibrous. a shell is said to be of a fibrous structure when a fracture would present a series of perpendicular fibres, as pinna. ficula. sw. a generic group of shells, consisting of those species of pyrula, auct. which have the true pear-shaped character. fig. , p. ficus. sowerby confines the name pyrula to these species. fimbria. megerle. corbis, lam. fimbriated. fringed; as murex fimbriatus, a delicate white species, with broad fringed varices. fissure. (_fissura_, a slit.) a slit or cut, a narrow perforation, as in emarginula and fissurella. fissurella. brug. (_fissura_, a fissure.) _fam._ calyptracia, lam. branchifera, bl.--_descr._ patelliform, oval or oblong, radiated; apex anterior, perforated.--_obs._ the fissurellæ are known from patellæ by the perforation in the apex. fig. . the catalogue published by the author in the conchological illustrations, enumerates species. fistulana. lam. (_fistula_, a pipe.) _fam._ tubicolæ, lam. adesmacea, bl.--_descr._ a transversely elongated, equivalve, inequilateral bivalve, enclosed by a septum within the widest, closed extremity of a straight calcareous tube. fistulana is known from gastrochæna by the straightness of the tubes, and the oblong state of the valves. fig. , fistulana clava. flexuous. having windings or bendings. _ex._ the tellinæ are known by the twist or flexuosity in the posterior ventral margin of the shell. florillus. montf. a genus of microscopic foraminifera. fluviatile. (fluviatilis.) belonging to a river or running stream. _ex._ limnæa fluviatilis. fluviatile conchacea. see conchacea. foliated, or foliaceous. (from _folium_, a leaf.) when the edges of the successive layers of which a shell is composed are not compacted but placed apart from each other, projecting like tiles, the shell is said to be of a foliated structure. the common oyster, fig. , presents a familiar example. foraminifera. d'orb. (_foramen_, a hole or pit.) an order established for minute many chambered internal shells, which have no open chamber beyond the last partition. lamarck, d'orbigny, and other writers have placed them among the cephalopoda in their systems, but du jardin, on comparing the fossils with some recent species of the same class, arrived at the conclusion, now generally adopted, that they constitute a distinct class, much lower in degree of organization than even the radiata. not recognizing these microscopic bodies as shells, properly so called, but considering them sufficiently numerous and interesting to form a distinct branch of study, i do not think it desirable to describe the genera, or to present any arrangement of them in this work. fornicated. arched or vaulted, as the exfoliations on the costæ of tridacna elongata, fig. . fossil shell. a shell is considered to be in a fossil state when, the soft parts having ceased to exist, it is deprived of all its animal juices, has lost all, or nearly all its natural colour, and is thus changed in its chemical composition, when little or nothing is left but a mere bone, which is embedded in a sedimentary deposit. in this state, it is fragile, prehensile to the tongue, and either destitute of colour or tinged with the diluted mineral matters which pervade the stratum in which it lies. in some cases, the mineral composition of the shell is so completely changed as no longer to present its proper structure, consisting of successive oblique layers of shelly matter; but is altered into a fibrous structure, composed of rhomboidal particles. an example of this will be found in the belemnites, which if broken, shew the perpendicular fibres. in other cases, the matter which has entered and filled up the cavities of the shell has become silicified, or changed into flint, and the shell itself has been decomposed and fallen off, so as to leave nothing but an external or internal cast of its form, in flint. this is called a conchyliomorphite by continental writers. some of the most important of geological data are obtained by a minute comparison of fossil shells, found in various beds, with recent ones presenting the nearest resemblance to them. some species of fossil shells are considered as identical with recent species. and many geologists seek to fix the chronology of the different strata by the number of species which they inclose bearing a resemblance to the recent species. indeed, all who would study geology with success, will find it indispensably necessary to obtain a thorough knowledge of conchology. fragella. sw. a sub-genus of monodonta, corresponding with the genus clanculus, montf. consisting of m. pharaonis (fig. ), and similar species. sw. p. . fragile. (_fragilis._) tender, easily broken. free shell. one that is not attached. free valve. in attached bivalve shells, one only is fixed; the other is then _free_, as far as to the action of opening and shutting. fresh-water shells, (sometimes described as aquatic) are those which either inhabit rivers, running pools and ditches, in which case they are _fluviatile_; or wells and ponds of standing water, &c. fresh-water shells are either thin and horny in their texture, as the limneana of lamarck; or are covered with a compact, smooth, horny epidermis. they are generally simple in form, subject to corrosion where the epidermis is wounded or broken, and are circumscribed with regard to the classes and genera to which they belong. the family of nayades includes nearly all the fresh-water bivalves; and the melaniana and limneana are the principal among univalves. frondicularia. defr. a genus of microscopic foraminifera. front. the surface of a shell on which the aperture appears. fulcrum. that part of a shell on which any other part rests or turns. the term is applied more particularly to the tumid part in the hinge of bivalve shells on which the ligament is fixed. fulgur. montf. pyrula perversa, auct. and such other species as have an angulated spire. fig. . fusiform. (_fusus_, a spindle.) shaped like a spindle, swelling in the centre and tapering at the extremities. _ex._ fusus, fig. . fusus. brug. (a spindle.) _fam._ canalifera, lam. siphonostomata, bl.--_descr._ fusiform, turrited, with many rounded whorls; aperture generally oval, terminating in a long straight canal; operculum horny, pyriform.--_obs._ the fusi are subject to considerable variations in form. the recent species are numerous and do not appear to be confined to any climate. the fossil species are also numerous, chiefly abounding in the tertiary formations. the recent species are mostly tropical. fig. , f. colus. galathÆa. brug. potamophila, sow. megadesma, bowd. galea. klein. purpura, auct. galeolaria. lam. (from galea, a helmet or crest.) a genus composed of species of serpula, auct. distinguished as being fixed by the side of the shell, and having the anterior extremity erect, the aperture terminating in a tongue-shaped projection.--_obs._ this genus is said by lamarck to resemble vermilia in other respects, but to differ in having the anterior part raised. fig. , g. decumbens. africa and australia. galeomma. turt. _fam._ pholadaria, lam.--_descr._ thin, oval, equivalve, equilateral, with the ventral margin gaping; hinge with one cardinal tooth in each valve; muscular impressions two, approximate; palleal impression interrupted, not sinuated; ligament small, partly internal, partly external, fixed on a prominent fulcrum.--_obs._ the wide hiatus in the ventral margins of this equilateral shell prevents the possibility of confounding it with any other. four or five recent species are known, one of which is found on the coast of sicily, and also in the british channel. g. turtoni, fig. . galericulus. (_galericulum_, a little cap or bonnet.) velutina, auct. fig. . galerus. humph. calyptrÆa, lam. gaping. (_hians._) bivalve shells are said to gape when the margins do not meet all round. _ex._ gastrochæna, fig. . gari. schum. psammobia, lam. gasteropoda. lam. ([greek: gastêr], _gaster_, belly; [greek: pous, podos], _pus_, _podos_, a foot.) the second order of the class mollusca, lam. containing those molluscous animals whose organs of locomotion are ventral. most of the shells belonging to this order are patelliform, placed upon the back of the animals, which rest or crawl upon the belly. this order is divided into pneumonobranchiata, that is, those which breath air, or land molluscs; and hydrobranchiata, or those which breath water, marine or fresh-water molluscs. fig. to . gastranea. schum.? corbula, auct. gastrochÆna. speng. ([greek: gastêr], _gaster_, belly; [greek: chaino], _chaino_, gape.) _fam._ pholadaria, lam. pyloridea, bl.--_descr._ equivalve, regular, inequilateral, with a wide, oblique, ventral hiatus, enclosed in a curved pyriform tube. differing from galeomma in being a free, oblique shell; from fistulana, in the oval shape of the valves, and the curve of the tube; from aspergillum and clavagella, in both valves being free.--_obs._ the gastrochænæ are found in the hollows of massive shells or other marine substances. fig. , g. modiolina. gastroplax. bl. umbrella, lam. de blainville described this genus from a specimen in which the shell had been, probably by accident, placed upon the under part of the animal, and not discovering his error until afterwards, gave it the above name. geomitra. sw. a sub-genus of geotrochus, sw. founded on a trochiform species of helix, with coronated nodules on the whorls. helix bicarinata, sow. zool. journ. , pl. , fig. . sw. page and . geophonus. montf. conch. syst. t. , p. . a genus of microscopic foraminifera. geotrochus. sw. helix pileus, auct. (fig. ,) and other trochiform species. divided into the sub-genera pithohelix, geotrochus, hemitrochus, gonidormus, and geomitra. sw. p. and , described at page . geovula. sw. a sub-genus of melampus (auricula), consisting of oval species, resembling auricula midæ, fig. . gervillia. defr. _fam._ margaritacea, bl. malleacea, lam.--_descr._ equivalve, oblong, oblique; hinge long, straight, having small, irregular, transverse ligamentary pits.--_obs._ this genus of fossil shells, found at various geological periods, from the lias to the baculite limestone in normandy, is now extinct. in general form it resembles avicula, but in the hinge it approaches perna. fig. , g. avicularis. giberula. sw. a genus separated from marginella, auct. and thus described, "sub-oval; spire slightly prominent; top of the outer lip dilated and gibbous; base of the inner lip with plaits; inner lip broad, spreading. g. zonata. enc. méth. , f. ." gibbose or gibbous. (_gibbosus._) bunched out, embossed, having a lump or swelling of any kind. _ex._ bulinus lyonetianus, (fig. .) named gibbus by de montfort. ovulum gibbosum. gibbus. montf. bulinus _lyonetianus_, lam. pupa, bl. fig. . gioenia. a name given in the encyclopédie méthodique, to the plates of the stomach of bulla lignaria. glabella. sw. marginella glabella (fig. ), goodallii, auct. and similar species. glandina. schum. polyphemus, montf. glandiolus. montf. a genus of microscopic foraminifera. glauconome. gray. _fam._ solenacea, lam.--_descr._ oblong or oval, transverse, slightly ventricose, equivalve, inequilateral; margins close, rounded anteriorly, somewhat acuminated posteriorly; hinge teeth, three in each valve, of which the central in one, and the posterior in the other, are bifid; muscular impressions anterior, elongated, marginal; posterior sub-quadrate; palleal impression, having a long sinus; ligament oblong, external; epidermis thin, horny, green, folded over the margins.--_obs._ this shell, of which only one species is known, inhabits some of the rivers in china. c. chinensis, fig. . globigenera. d'orb. a genus of microscopic foraminifera. globose. (_globosus._) rounded like a globe or ball, as the species of helix, represented in fig. . globularia. sw. a sub-genus of natica, consisting of globose species. (sw. p. .) _ex._ n. lineata, fig. . globulus. sow. min. con. ampullaria, auct. glycimeris. lam. _fam._ solenacea, lam. pyloridea, bl.--_descr._ equivalve, transverse, oblong, thick, compressed, gaping at both extremities; hinge callous, without teeth; ligament large, external, prominent; epidermis thick, black, horny, folded over the margins; muscular impressions two, distant, running into the irregular palleal impression which unites them.--_obs._ but few species of this singular genus are known; lamarck describes two species from the northern seas. blainville is of opinion that they belong to the family of the nayades. fig. , g. siliqua. gnathodon. gray. ([greek: gnathos], _gnathos_, jaw-bone; [greek: odos], [greek: odontos], _odontos_, tooth.) _fam._ mactracea, lam.--_descr._ ovate, posteriorly angulated, equivalve, thick, ventricose, inequilateral, covered with a greenish brown epidermis; umbo distant, prominent; hinge having in one valve a sharp, angular, notched, cardinal tooth, and two lateral teeth, the posterior of which is elongated, and the anterior angulated, tortuous, shaped like a jaw-bone; in the other valve, two cardinal and two lateral teeth, the anterior of which is wedge-shaped; ligament internal, cuneiform, placed in a deep cardinal pit proceeding from the umbones; muscular impressions two; palleal impression having a slight sinus.--_obs._ only one species is known, g. cuneatus, fig. , from new orleans. it is known from all other shells by the character of the hinge. goniatites. de haan. a genus composed of species of ammonites, auct. in which the last whorl covers the spire and the sinuations of the septa are angulated. fig. , g. striatus. gonidomus. sw. a sub-genus of geotrochus, sw. pupa pagodus, auct. sw. p. . goniostoma. sw. a sub-genus of bulimus, thus described, "spire elongated, of few whorls; aperture contracted at each end; lips margined; the pillar curving inwards; the base slightly notched. g. erubescens, _sw._ zool. journ. i. pl. , f. ." sw. p. . goniostomatÆ. bl. a family belonging to the order asiphonibranchiata, bl. containing the genera solarium and trochus. gonospira. sw. a sub-genus of pupa, thus described, "spire perfectly cylindrical, of equal thickness, the tip obtuse, with the whorls large; aperture oval; lips thickened; pillar with or without a plait. g. polanga, _desh._ lesson, voy. pl. , f. ." sw. p. . granulated. (_granum_, a grain.) covered with minute grains, rough. the granulated lip of oniscia, (fig. ) will serve as an example. grateloupia. moulins. _fam._ nymphacea, lam.--_descr._ equivalve, inequilateral, sub-cuneiform, rounded anteriorly, sub-rostrated posteriorly; hinge with three cardinal teeth, a series of five or six irregular, small, diverging teeth behind the umbones, and one lateral anterior tooth in each valve; ligament external; muscular impressions two; palleal impression sinuated posteriorly.--_obs._ this genus (donax irregularis, bast.) is only known in a fossil state. fig. , g. moulinsii. gryphÆa. lam. (from gryps, a griffin.) _fam._ ostracea, lam.--_descr._ inequivalve, free; lower valve large, concave; with the umbo prominent, incurved; upper valve small, flat, opercular; hinge toothless, with a curved, depressed area; one muscular impression.--_obs_. these shells, which approach the oysters, are of a more regular form, and are remarkable for the curved, produced beak of the lower valve. they are only known in a fossil state, belonging to the more ancient strata. fig. , g. incurva. the recent species mentioned by lamarck is not a true gryphæa. gymnolepas. a generic name used by de blainville to include otion and cineras, leach. gymnosomata. bl. the second family of the order aporobranchiata, in the system of de blainville. the animals belonging to this family are destitute of shells. gypidea. dalman. a genus of brachiopoda, thus described, "larger valve with the umbo rostrated, remote from the hinge; with the canal large, deltoid; bilocular within." pentamerus, sow. fig. . , g. conchidium, copied from dalman. gyrogona. lam. a genus of microscopic foraminifera. gyroidina. d'orb. a genus of microscopic foraminifera. haliotidÆ. sw. a sub-genus of calyptræa. calyptrÆa dilatata. sowerby's genera of shells, fig. . haliotis. auct. ([greek: als], _als_, sea; [greek: ous], [greek: ôtos], _otos_, ear.) _fam._ macrostomata, lam. otides, bl.--_descr._ auriform, broad, depressed, pearly within, rough, costated, tuberculated without; spire short, flat, consisting of one or two whorls; aperture wide; ovate; columella laminar, flat, oblique; a spiral series of perforations running along the dorsal margin.--_obs._ the splendid shells belonging to this genus are remarkable for the pearly iridescence of the inner surface, and the row of holes following the course of the spire. the soft parts are eaten in guernsey and jersey, and reckoned delicious. they belong to temperate and tropical climates. fig. , h. rubra. , padollus, montf. haliotoid. (_haliotis_ and [greek: eidos], _eidos_, form.) ear-shaped. hamiform. (_hamus_, a hook.) curved at the extremity. hamites. parkinson. (_hamus_, a hook.) _fam._ ammonacea, lam.--_descr._ elongated, cylindrical, chambered, recurved at the smaller extremity, annulated; septa lobed and sinuated.--_obs_. this remarkable fossil from the baculite limestone in normandy, differs from baculites in being curved at one extremity, a circumstance from which its name is derived. some small species are found in chalk-marle, folkstone. fig. *. h. cylindricus. harpa. brug. (_harpa_, a harp.) _fam._ purpurifera, lam. entomostomata, bl.--_descr._ oval, ventricose, longitudinally and regularly costated; spire short, with rounded, dome-like whorls; aperture wide, emarginated; outer lip thickened, reflected, composing the last costa or rib; inner lip polished, spread over part of the body whorl, terminating in a point.--_obs._ this beautiful genus of shells is so clearly defined by the regular, longitudinal ribs that adorn the external surface, suggesting the idea of a stringed instrument, that there is no danger of confounding it with any other. h. multicostata, (buccinum costatum, linn.) and h. ventricosa, are among the most elegant of the testaceous productions of the sea both in form and colouring; the former is rare. the recent species are not numerous, they inhabit the indian ocean. a fossil species occurs at grignon, near paris. fig. , h. ventricosa. harpax. parkinson. part of plicatula, auct. harpula. sw. a group of shells separated from voluta, auct. thus described, "shell generally tuberculated or longitudinally ribbed; apex of the spire papillary, smooth, and in general distorted; pillar with numerous distinct plaits; the upper, small and slender, the lower, thickest and shortest."--_type_, h. vexillum. (voluta, auct.) haustator. montf. a genus proposed to include those species of turritella, auct. which have angulated whorls. haustellaria. sw. a sub-genus of murex, consisting of species with long canal and no spines. murex haustellum, fig. . haustrum. humph. purpura, lamarck. helcion. montfort. a genus composed of species of patella, which have the apex distinctly and prominently bent forwards. _ex._ p. pellucida, fig. . helenis. montf. a genus of microscopic foraminifera. helicella. fer. one of the sub-genera into which de ferussac has divided the genus helix, consisting of depressed species with large umbilicus, such as helix algira, fig. . gonites montf. heliciform. shaped like shells of the genus helix. helicigona. one of de ferussac's sub-genera of the genus helix, consisting of angulated species, such as carocolla lamarckii, fig. . helicina. lam. _fam._ colimacea, lam. ellipsostomata, bl.--_descr._ globose, compressed, or angulated, generally light and thin; aperture trigonal or semilunar; outer lip thickened and generally more or less reflected; inner lip spread over the body whorl, frequently callous near the columella, which is short, and terminates in a notch, angle, or slight callosity.--_obs._ this genus of land shells, distinguished from the genus helix, by having an operculum and a thickened columellar lip, differs also from cyclostoma in having the aperture semicircular or angular, the peritreme discontinuous and the operculum concentric. these shells are generally small in size, and simple in form. lamarck describes only three or four species. mr. gray described some others in the zoological journal, and in a work shortly to be published by the author, a monograph of the genus will contain descriptions and figures of at least distinct species; some of which have been lately brought to this country by mr. cuming from the philippine islands. they mostly belong to tropical climates. helicites. bl. part of the genus nummulites, lam. rotalites and egeon, montf. helicogena. fer. a sub-genus of helix, consisting of species, which, like the common garden snail, fig. , are globose and simple in form. helicolimax. fer. vitrina, drap. h. pellucida, fig. . helicophanta. fer. a sub-genus of helix, consisting of ear-shaped species with large open apertures. helicostyla. fer. a sub-genus of helix, consisting of species with numerous whorls, as h. epistylium, fig. . helisoma. sw. a sub-genus of planorbis. sw. p. . helix. auct. _fam._ colimacea, lam.--_descr._ orbicular, light, generally globular; spire short, last whorl ventricose, aperture oblique, peritreme reflected, interrupted by the most prominent part of the body whorl; columella confluent with the outer lip, and contiguous to the axis of the shell. no operculum; a thin epidermis.--_obs._ the land shells composing this genus are found in all parts of the world; the common snail, h. aspersa, is well known as a destructive animal in our gardens. the genera helix, achatina, bulinus, clausilia, anostoma, &c., have been united under one generic name by de ferussac, and again divided under the following sub-generic names, each of which we shall illustrate by a figure. genus helix: _sub-genus_ , _helicophanta_, consisting of species with large apertures, like vitrina; helix brevipes. _s. gen. _, _cochlohydra_, succinea amphibia, drap. _s. gen. _, _helicogena_, consisting of the common species with the last whorl large; helix hæmastoma, h. contusa, (streptaxis, gray,) h. aspersa. _s. gen. _, _helicodonta_, consisting of species with teeth or folds on the columella; polydonta, montf. anostoma, helix nux-denticulata. _s. gen. _, _helicigona_, carocolla, geotrochus. _s. gen. _, _helicella_, consisting of depressed species with a large umbilicus; h. citrina (naninia, gray.) _s. gen. _, _helicostyla_, consisting of species with a simple aperture, like the helicogenæ, but with the whorls increasing very gradually; h. epistylium. _s. gen. _, _cochlostyla_, bulinus. _s. gen. _, _cochlitoma_, achatina. _s. gen. _, _cochlicopa_, polyphemus glans. _s. gen. _, _cochlicella_, bulinus decollatus. _s. gen. _, _cochlogena_, azeca tridens. _s. gen. _, _cochlodonta_, pupa uva. _s. gen. _, _cochlodina_, clausilia macascarensis, balea fragilis. the last three sub-genera are included in the genus odostomia of fleming. we give an example of each of these sub-divisions, for the sake of presenting the reader with the principal variations to which the genus is subject. the established genera will be characterized in their places. fig. to . helixarion. fer. vitrina, drap. differing from helicolimax in the structure of the animal. fig. . hemicardium. cuv. ([greek: hêmisus], _hemisus_, half, [greek: kardia], _cardia_, heart.) cardium hemicardium, fig. **, and several similar species. hemicycla. sw. a sub-genus of helix. hemicyclonosta--see cardilia. hemicyclostomata. bl. the fourth family of asiphonibranchiata, bl. described as "more or less globular, thick, flattened on the under side; spire very short; aperture large, semilunar, entire; its outer edge hollowed; its inner or columellar edge straight, sharp and septiform." this family answers to the genus _nerita_ of linnæus, and to the family neritacea of lamarck. it contains the genera natica, nerita, neritina, and navicella. hemimactra. sw. a sub-genus of mactra, thus described: "general form of _mactra_; but the cardinal teeth entirely wanting; cartilage internal, central, in a large triangular cavity; lateral teeth / , distinct, lateral, striated: connected to the _glycimeri_. h. gigantea, _lam._ v. . no. . grandis, _sw._ sp. nov." sw. p. . hemimitra. sw. a sub-genus of paludomus, sw. (melanianæ.) hemiodon. sw. a sub-genus of anodon, described as having "tubercles or undulations on the hinge margin. h. undulatus, purpurascens and areolata." hemisinus. sw. a sub-genus of melania, thus described: "general shape of _melania_; but the base of the aperture is contracted and emarginate; outer lip crenated. h. lineolata, griff. cuv. xii. pl. . fig. ." hemitoma. sw. a sub-genus of emarginula, thus described: "patelliform; the fissure not cut through the shell, but merely forming an internal groove. h. tricostata, _sw._ sow. gen. fig. ." hemitrochus. sw. a sub-genus of geotrochus, sw. h. hæmastoma. sw. p. . heptalasmis. leach. ([greek: hêpta], _hepta_, seven; [greek: elasma], _elasma_, plate) a small shell resembling pentelasmis, from which it differs in the number of valves, being composed of seven valves according to leach, and of eight according to gray, who counts the dorsal valve, which is jointed, as _two_, and names his genus octolasmis. fig. , h. warwickii. hercoles. montf. a microscope shell, appearing from de montfort's figure to resemble trochus _imperialis_ in shape. herion. montf. lenticulina, bl. microscopic. hermaphrodita. bl. the third sub-class of paracephalophora, bl. divided into, sect. , _symmetrical_, containing the orders cirrobranchiata and cervicobranchiata; sect. , _non-symmetrical_, order, scutibranchiata. hermes. montf. a genus composed of conus _nussatella_, auct. and other elongated, cylindrical, striated species. fig. . heterobranchiata. bl. the fourth order of the class acephalophora, bl. containing no testaceous mollusca. heteropoda. lam. the fifth order of the class mollusca, lam. this order contains but one genus of shells, viz. carinaria, fig. . heterostegina. d'orb. a genus of microscopic foraminifera. hiatella. daud. fam. lithophagidæ, lam. a genus composed of species of saxicava, auct. which have sharp, angulated, posterior ridges, a circumstance which occurs to many species in a young state, which afterwards become rounded off. fig. , hiatella biaperta. hiatula. sw. a genus proposed to include those species of oliva, auct. which have widened apertures. _ex._ o. subulata, fig. . hibolithes. montf. a genus composed of species of belemnites, auct. which are swelled towards the apex, and contracted near the centre. b. hastatus, auct. fig. . himantopoda. schum. malleus, auct. hinge. the edge of the bivalve shells near the umbones, including the teeth and ligament. hinnites. defr. a generic name proposed for pecten pusio, auct. remarkable for the irregularity of the outer surface, which would almost lead to the belief of its being an attached shell. fig. , h. pusio. hippagus. lea. (_horse boat._) a minute fossil shell, resembling isocardia in form, but destitute of hinge teeth. h. isocardioides, fig. . hippochrenes. montf. species of rostellaria, auct. with the outer lip spread. fig. . r. columbaria. hipponyx. ([greek: hippos], _hippos_, horse; [greek: onux], _onyx_, nail or hoof.) _fam._ rudistes, lam.--_descr._ inequivalve, sub-equilateral, rather irregular, destitute of ligament and hinge teeth; lower valve attached, flat, sub-orbicular, with a muscular impression, composed of two lunulate portions, meeting at one extremity, and presenting the form of a horse-shoe; upper valve conical, with the apex inclined backwards, and the muscular impression marginal.--_obs._ the earlier naturalists having only met with the upper valve of these shells, placed them among the patelliform univalves; to some of which, particularly pileopsis, they bear a very strong resemblance. the species of hipponyx are numerous, and till lately only known in a fossil state. the recent species belong to tropical climates: the fossil species are found in the tertiary beds. fig. , h. cornucopia. hippopodium. conybeare. _fam._ cardiacea, lam.--_descr._ equivalve, obliquely transverse, heavy, deep, inequilateral, umbones incurved; ventral margin sinuated, so as to give a bilobed appearance to the shell; hinge incrassated, with one rugged oblique tooth.--_obs._ these fossils are found in the upper beds of lias. fig. , h. ponderosum. hippopus. lam. ([greek: hippos], hippus; [greek: pous], _pous_, foot.) _fam._ tridacnacea, lam.--_descr._ equivalve, inequilateral, regular, subquadrate; lunule closed, flat, with crenulated edges; ventral margin deeply undulated; external surface fluted, with radiating ribs, which are transversely fringed with rows of tubular spines; hinge margin thick, with two long, compressed posterior lateral teeth in one valve, three in the other; ligament marginal, external.--_obs._ the shell thus described is rightly separated from tridacna, on account of the anterior dorsal margins being closed; whereas in tridacna there is a wide hiatus. only one species of this genus is known, which receives its name from its resemblance in form to a horse's foot, when held with the flat anterior dorsal margin downwards. few shells are found to concentrate so many beauties as the hippopus maculatus, commonly called the bear's-paw-clam; the delicate whiteness of the interior, the undulating edge, the radiated fluted columns, adorned at intervals by crisped fringes, and the richness of the variegated colouring, are such as to secure the admiration of the most superficial observer. from the indian archipelago. fig. , h. maculatus. hippurites. montf. _fam._ orthocerata, lam. rudistes, bl.--_descr._ tabular, rude, irregular, attached; lower valve cylindrical, more or less lengthened, apparently divided into sections by septa (considered by some authors as merely projecting layers of growth) having one or two lateral tubes within; upper valve round, flat, fixed on the aperture of the tubular valve like an operculum.--_obs._ this genus is known only in a fossil state, and but very imperfectly. lamarck places it among his chambered cephalopoda, &c. de blainville, considering it a true bivalve, enumerates it among his rudistes. cretaceous group. fig. , h. cornucopia. hortolus. montf. spirolina, lam. microscopic. hyalÆa. auct. (_hyalus_, glass.) _fam._ pteropoda, lam. thecosomata, bl.--_descr._ globose, glassy, transparent, with a triangular opening at the upper part where the dorsal portion advances beyond the ventral; ventral portion vaulted; dorsal more flat; lower extremity tridentate.--_obs._ the singular structures composing this genus were formerly taken for bivalves, and named anomia tricuspidata, &c. they are now known to belong to the class of molluscous animals, called pteropoda, from the wing-shaped organs of locomotion. a species of hyalæa occurs in sicily in a fossil state. recent species are found in the mediterranean, atlantic, and indian oceans. fig. , h. tridentata. hyalina, studer. vitrina, drap. hyaline. (_hyalus_, glass.) glassy, thin, transparent--_ex._ carinaria mediterranea, fig. . hydrobranchiata. bl. the first section of the order gasteropoda, lam. containing molluscs which breathe water only; divided into the families tritoniana, phyllidiana, semi-phyllidiana, calyptracea, bullæana, and aplysiana. hygromanes. fer. a sub-division of helix, containing h. limbata, auct. &c. gray's turton, p. . hyria. lam. a genus composed of species of nayades, distinguished by their alated dorsal margins, and lamellated lateral teeth. south america. hyria corrugata, fig. , hyria syrmatophora, fig. . hyridella. sw. a genus of "hyrianæ," sw. described as differing from hyria, auct. in having a cardinal as well as a lateral tooth in each valve. sw. p. . histrix. humph. ricinula, auct. janera. schum. a genus composed of species of pecten, auct. having oblique plicæ or calli on each side of the ligamentary pit. _ex._ p. plica, fig. . decadopecten, rüppell. janthina. auct. (_janthum_, a violet.) _fam._ neritacea, lam. oxystomata, bl.--_descr._ sub-globose, thin, fragile; spire short, consisting of few whorls; aperture angulated, at the anterior junction of the inner and outer lips; columella tortuous, contiguous to the axis; outer lip thin, sinuated in the centre.--_obs._ the shells composing this genus are celebrated for their beautiful purple colour. the animal possesses a small vesicular process, which keeps it floating on the surface of the water; it exudes a purple secretion when irritated. it is occasionally floated on to the shores of most temperate and tropical countries. fig. , j. fragilis. jataronus. adanson. chama, auct. iberus. montf. carocolla, lam. ibla. leach. _fam._ pedunculated cirripedes, lam.--_descr._ four valves, posterior pair elongated, anterior pair short, triangular; pedicle cylindrical, contracted at the base, hairy.--_obs._ i. cuveriana (fig. ) is brought from kangaroo island. icthyosarcolites. desmarest. _fam._ ammonacea, lam.--_descr._ chambered, slightly arcuate, laterally compressed; septa simple, leaving triangular articulations imbricated like the thick muscles of a fish. jesites. montf. a minute fossil resembling galeolaria. ilotes. montf. orbiculina, bl. a genus of microscopic foraminifera. imbricaria. schum. conohelix, sw. imbricated. (_imbrex_, a tile.) a shell is said to be imbricated when the superficial laminæ are arranged over each other in the manner of tiles. imperator. montf. a genus composed of species of the genus trochus, auct. with whorls angulated and stellated, having an umbilicus. _ex._ t. imperialis. some of the shells named imperator in the british museum belong to the genus calcar, montf. having no umbilicus. impression. see muscular impression. incrassated. (_crassus_, thick.) thickened, as the hinge of glycimeris, fig. . incurved. turned inwards or bent forwards. applied to symmetrical shells, when the point of the apex turns towards the anterior extremity, as in patella. the apex of a shell is said to be incurved when it is bent inwards, but not sufficiently so to be described as spiral. _ex._ ammonoceras, lam. fig. . indented. (_in_, in; _dens_, a tooth.) exactly the reverse of dentated; meaning a series of small cavities, such as might be produced by the entrance of teeth. the cast of a dentated surface would be indented. inequilateral. (_Æquus_, equal; _latus_, a side.) a term applied to a bivalve shell when its extent on one side of the umbones is greater than that on the other. when the sides are nearly equal, the term _sub-equilateral_ is used. inequivalve. (_in_; _æquus_, equal; _valva_, valve.) the two principal valves differing from each other in diameter or convexity. inferior valve is that which is attached to sub-marine bodies. only applied to attached bivalves. inferobranchiata. bl. the fourth family of the second section of paracephalophora monoica, bl. containing no testaceous mollusca. inflated. swelled, as bulla, fig. , . this term can only be applied to rotund shells of a light, thin texture. in other cases we should use the word ventricose. inflected. turned inwards. this term is applied to the outer lip of a spiral shell when it turns towards the body whorl. this is the case in cypræa, fig. . see reflected. infundibulum. montf. (_a funnel._) a genus formed of those species of calyptrÆa, lam. which, having a spiral septum, so nearly resemble trochus that some authors have placed them in that genus. one species named patella trochiformis. recent from south america, fossil from the tertiary beds. fig. , , calyptræa (infundibulum) pileus. inner lip. that edge of the aperture of an univalve shell which is near to the imaginary axis, as distinguished from the outer lip, or that which is on the opposite side. inoceramus. sow. _fam._ malleacea, lam. margaritacea, bl.--_descr._ thick, inequivalve, sub-equilateral, triangular, deep, with the umbones incurved; hinge formed of a series of transverse grooves.--_obs._ the larger valves of these fossil shells resemble the larger valve of gryphæa; but the hinge is quite distinct. the species described in mineral conchology are found in the blue marl, at folkstone, and in the chalk. i. lamarckii, (catillus, brong.) fig. . internal cast. the mould of a fossil shell, composed of matter which entered the shell in a soft state, and has subsequently hardened, when, the shell dropping off, the hardened substance which filled it is left to represent its internal form. internal ligament. a term used by some conchological writers signifying that the ligament of a bivalve shell is placed within the closed part of the hinge, so as not to be seen when the valves are shut. but the substance, formerly called the internal ligament, is now distinguished from the true ligament both in structure and use; and is now more properly called the cartilage, so that when the ligament is said to be internal, it must be understood that the internal cartilage is unaccompanied by any ligament properly so called, and when a shell is described as having two ligaments, as in the case of amphidesma, it means that the two substances are so far removed from each other in the hinge that they are no longer confounded together. internal shell is one which is enclosed in the soft parts of the animal, as a bone is enclosed in the flesh of a human body. the limax, or common garden slug, which has a testaceous shield beneath its mantle, is an instance of this. io. lea. a genus composed of several species of fresh-water shells which are considered as differing from melaniæ in having the anterior termination of the aperture produced into a point in some degree resembling the caudal canals of shells belonging to the family of canalifera, which are marine. io fusiformis and spinosus are described and figured in lea's work on the genus unio. jodamia. defr. a genus resembling birostrites, except that in jodamia one valve overwraps the other, while in birostrites the circumference of the valves is equal. iphigenia. gray. a sub-genus of clausilia, c. biplicata, &c. auct. gray's turton, p. . iridea. sw. a genus of "hyrianæ," sw. thus described:--"oblong ovate; bosses small, depressed, sulcated; inner cardinal tooth placed beneath the outer. i. granosa, _lam._ en. méth. . fig. ." iridina. auct. a genus belonging to the nayades, and resembling the anodontÆ, auct. but its peculiar characteristic is that the hinge lamina is tuberculated or crenulated in its whole length. sowerby unites all the genera of the family into the genus unio. fig. , i. elongata. irregular shells, are those which, being attached to, or imbedded in other marine bodies, have no constant form, but are modified in shape according to the substances to which they are fixed, as the chamacea, fig. to . irus. oken. comprehending pandora, petricola, saxicava, &c. isocardia. lam. ([greek: isos], _isos_, similar; [greek: kardia], _cardia_, heart.) _fam._ cardiacea, lam. chamacea, bl.--_descr._ cordiform, regular, equivalve, ventricose, with distant, diverging, involute, free umbones; hinge with two compressed cardinal, and one distant, compressed lateral teeth in each valve; ligament external, bifid, diverging in the direction of the umbones.--_obs._ the shells composing this genus are remarkable for the beautiful curvature of the diverging umbones. european and chinese seas. fig. , i. moltkiana. keel. a flattened ridge, resembling the keel of a ship. as that on the back of carinaria vitrea, fig. , and those on the whorls of some spiral shells. a shell characterized by a keel or keels is said to be carinated. kellia. turton, mya suborbicularis, montague. labis. oken. monodonta, lam. labium, or inner lip,--is used to express that side of the aperture which is nearest to the axis and generally contiguous to the body whorl. the lower part of this, when sufficiently distinct from that part which overwraps the body whorl, is called the columella. labrum, or outer lip,--is the edge of the aperture at the greatest distance from the axis. lacinea. humph. chama, lam. lacuna. turt. _fam._ turbinacea, lam.--_descr._ globose, thin, covered with a smooth epidermis; spire short, consisting of few rapidly increasing whorls; aperture semilunar, rounded at the extremities; columella oblique, reflected over part of the umbilicus; umbilicus forming a lengthened area behind the columella. northern shores. fig , l. pallidula. lagenula. montf. a genus of microscopic foraminifera. lamellated. (_lamella_, a thin plate.) when the layers of which a shell is composed, instead of being compacted into a solid mass, are separated, overlying each other in the manner of tiles, with the edges prominent, the structure is said to be lamellated or foliaceous. lamellibranchiata. bl. the third order of the class acephalophora, bl. consisting of bivalve shells, divided into the families ostracea, subostracea, margaritacea, mytilacea, polydontes, submytilacea, chamacea, conchacea, pylorides, adesmacea. lamellipedes. lam. (_lamella_, a thin plate, _pes_, a foot.) the third section of the order conchifera dimyaria, containing bivalves, with the foot of the animal broad and thin; divided into the families conchacea, cardiacea, arcacea, trigonacea, nayades. fig. . to . lampas. montf. lenticulina, bl. a genus of microscopic foraminifera. lamprodoma. sw. a genus of "olivinæ," sw. thus described:--"mitriform; spire produced, conic; resembling mitrella in shape, but the suture is channelled; the aperture effuse at the base, contracted above; lower half of the pillar with to plaits. volutella, zool. ill. ii. series, pl. . f. . (_fig. ._ )" sw. p. . lamproscapha. sw. a sub-genus of "anodontinæ," sw. thus described:--"shell not winged, elongate, pod-shaped; teeth none; bosses near the anterior extremity. tropical america only? l. ? elongata. _sw._ zool. ill. i. . ensiforme, _spix._ braz. test. siliquosa. braz. test. pygmæa. ib." sw. p. . lamprostoma. sw. a sub-genus of canthorbis (trochus), described at p. , lardn. cyclop. malac. lampus. humph. terebratula, lam. lanceolate. lengthened like a lance. lanistes. montf. reversed species of ampullaria, fig. . laplysia. see aplysia. laplysiacea. lam. (properly aplysiacea) a family belonging to the first section of the order gasteropoda, lam. containing the genera aplysia and dolabella. fig. , . larva. humph. fissurella, lam. lateral. (_latus_, a side.) the lateral teeth are those which, taking their rise near the umbones, proceed to some distance towards the sides of the shell; as distinguished from the cardinal teeth, which receive their full developement close to the umbones. lateral muscular impressions are those which are placed at a distance from each other, on the opposite sides of the shell. latiaxis. sw. a genus of "eburninæ," sw. corresponding with the genus trichotropis. sow. (sw. malac. p. .) latirus. montf. a genus composed of species of fusus, auct. which have an umbilicus and are turriculated. lauria. gray. a sub-genus of pupa, containing p. umbilicata, &c. (gray's turton, p. .) leguminaria. schum. a genus composed of species of solen, auct. which have an internal longitudinal bar or rib. fig. . s. radiatus, lam. leila. gray? described as having the hinge edge smooth like iridina, but having a "sharp siphonal inflexion." (syn. b. m. p. .) leiodomus. sw. a genus of "buccininæ," sw. consisting of terebra vittata and other similar species. this genus corresponds with bullia, gray. leiostoma. sw. a genus of "fusinæ," sw. thus described, "equally fusiform," (with fusus) "but ventricose in the middle; shell entirely smooth, almost polished; inner lip thickened, and vitreous; base of the pillar very straight. fossil only. (_fig. ._) l. bulbiformis. en. méth. . f. ." lembulus. leach. a genus composed of oval species of nucula, resembling n. margaritacea, fig. . lendix. humph. pupa, lam. length. see measurement. lenticular. (_lens._) of a circular, convex form, as pectunculus, fig. . lenticulina. lam. a genus of microscopic foraminifera.--_descr._ lenticular, sub-discoidal, compressed, convolute, symmetrical; aperture notched; chambers few in number; visible on the exterior, radiating from the centre of the disk. lepadicea. bl. the first family of the class nemantopoda, bl. this family consists of the same animals which constitute the pedunculated cirripedes of lamarck, and part of the genus lepas in the system of linnæus. it contains the genera gymnolepas, pentalepas, polylepas and litholepas. lepas. ([greek: lepas], _lepas_, a rock.) the linnæan name lepas contains all the cirripedes or multivalves, the different kinds of which are not distinguished in the accounts given by early writers of the habits of the animals. (fig. to .) it was formerly applied to the limpets or patella. in fact, the ancient definition was "concha petræ adhærens," and would apply to any shells attached to rocks. leptÆna. dalman. a genus belonging to the brachiopoda; and thus described:--"hinge compressed, rectilinear, frequently exceeding the width of the shell." it forms part of the genus producta, sow. fig. , l. depressa. leptoconchus. rüppell. ([greek: leptos], _leptus_, thin; [greek: konchos], _conchos_, shell.) this shell resembles a young magilus in general appearance, although the animal is said to differ. in the young magilus also, the inner lip is reflected over the body whorl, which is not the case in leptoconchus. red sea. fig. . leptoconus. sw. a sub-genus of conus, consisting of conus grandis, amadis, duplicatus, australis, &c. sw. p. . leptolimnea. sw. a sub-genus of limnea, described as being nearly cylindrical. limnea elongata, sow. gen. fig. . lepton. turton. solen squamosus, montague, and other species described as "flat, nearly orbicular, equivalve, inequilateral, a little open at the sides. hinge of one valve with a single tooth, and a transverse linear lateral one on each side; of the other valve, with a cavity in the middle and a transverse deeply cloven lateral tooth each side, the segments of which divaricate from the beak." to represent this genus we have figured l. squamosum in the plates, fig. . british. leptospira. sw. a sub-genus of bulinus, thus described: "spire excessively long, sub-cylindrical; body whorl largest; outer lip thickened; aperture oval; no teeth, striata, _sw._ chem. . f. . signata _sw._" sw. p. . leucostoma. sw. a genus of "achatina," sw. described as resembling achatinella, but having a "thick pad" at the top of the "upper lip," and another over the base. l. variegata, sw. lardn. cyclop. malac. fig. . p. . leucotus. sw. a sub-genus of natica, described as intermediate between sigaretus and lacuna. sigaretus _cancellatus_, lam. (sw. malac. p. .) licium. humph. ovula, lam. (ovulum.) ligament. (from _ligo_, to bind.) the true ligament is always external, and serves the purpose of binding the two valves of a shell together externally by the posterior dorsal margins. there is another substance, called by gray the _cartilage_, which is elastic and of a condensed fibrous structure, placed within the ligament, either close to it, or at a more interior part of the shell; it is sometimes contained in a pit, formed for its reception, in the centre of the hinge. this substance, being elastic, keeps the valves open, unless drawn together by the counteracting force of the adductor muscles. when conchologists speak of a shell as having the ligament external, the real meaning is that these two substances are so close together as in appearance to constitute one body placed outside the shell so as to be seen when the valves are closed. when two ligaments are spoken of, as in amphidesma, the meaning is that the cartilage occupies a separate place on the hinge. ligamentiferous. (_ligamentum_, a ligament, _fero_, to bear.) having or containing the ligament, as the cardinal pit in mya, fig. . ligula. leach. a genus containing the more rounded and less gaping species of lutraria, auct. fig. , lutraria papyracea. ligulate. (_ligula_, a slip, a shoe-latchet.) thin, slender, like a slip, or neck of any thing, as the anterior muscular impression of lucina, fig. . ligumia. sw. a sub-genus of unio, thus described:--"very long and pod-shaped; bosses depressed; cardinal teeth moderate. s. recta. lam. vi. . p. ." sw. p. . liguus. montf. a genus containing species of achatina, auct. which have rounded apertures and lengthened spires, differing from his polyphemi, which have lengthened apertures. a. virginea, auct. fig. , is the type of this genus. lima. brug. (_lima_, a file.) _fam._ pectinides, lam. subostracea, bl.--_descr._ equivalve, inequilateral, compressed, oblique-auriculated, oval, radiately ribbed or striated, imbricated, covered with a light brown epidermis; hinge with a triangular disc between the umbones, divided in the centre by a triangular ligamentary pit without teeth; muscular impression one, sublateral, sub-orbicular.--_obs._ the shells thus described are marine, two or three species being found on our coasts, and fossil species occurring in lias, inferior oolite, calcaire-grossiér, &c. they differ from pecten in having a wide hiatus for the passage of a byssus, by which they are occasionally attached, and also in the triangular disc, which separates the umbones. the animal makes use of the valves of his shell as natatory organs, working them like fins or paddles, and by this means proceeding at a rapid rate through the waters. l. squamosa, fig. . limacina. cuv. (_limax_, a snail.) _fam._ pteropoda, lam.--_descr._ papyraceous, fragile, planorbicular, sub-carinated, obliquely convolute; spiral side rather prominent, the other side umbilicated; aperture large, entire, not modified, peristome sharp.--_obs._ this is spiratella, bl. the shell figured as limacina in sowerby's genera, under "pteropoda," is an _atlanta_. our representation of spiratella limacinea, fig. . is copied from blainville. limacinea. lam. a family of the order gasteropoda, lam. including the following . cryptella. spire mammillated; a septum. fig. . . parmacella. flat, haliotoid, spiral. fig. , . . testacellus. sub-spiral. fig. . . limax. incomplete. fig. . . plectrophorus. conical. fig. . . vitrina. heliciform, hyaline. fig. , . limacinea. bl. the third family of the order pulmobranchiata, bl. described as containing shells very variable in form, most frequently inclining to globular or oval; the apex always obtuse; aperture variable, but never emarginated. all the limacinea are phytophagous and terrestrial. this family answers to the genus helix of linnæus and to the colimacea of lamarck, leaving out the auriculacea. it contains the genera succinea, bulinus, achatina, clausilia, pupa, partula, helix, vitrina, testacella, limacella, limax. limax. _lam._ limacinea, lam. and bl.--_descr._ internal irregular, sub-quadrate, scutiform, crystalline; apex rounded, indistinct; epidermis, light brown, thin, extending beyond the margin.--_obs._ the shell is placed under the scutellum of the common garden slug. fig. , l. antiquorum. limnacea. bl. the first family of the order pulmobranchiata, bl. the shells of this family are described as thin, with the outer lip always sharp. it contains the genera limnea, physa, planorbis. limneana. lam. a family of the order trachelipoda, lam. containing the following genera:-- . limnÆa. spire produced; including _physa_. fig. to . . planorbis. spire orbicular; including _planaria_. fig. , . limnea. lam. ([greek: limnas], _limnas_, lacustrine.) _fam._ limnacea, lam. and bl.--_descr._ oblong, light, thin; spire variable in length, acute; last whorl large, aperture large, longitudinal, entire; inner lip spread over a portion of the last whorl; columella forming an oblique fold; outer lip rounded at each extremity, thin.--_obs._ these light horn-coloured shells are common in standing pools, ponds and ditches, in various parts of europe. they resemble the amber shell (succinea) in shape, but the animal of the latter is amphibious, and the shell of a bright amber colour. l. stagnalis, fig. . l. auricularia, fig. . (radix, montf.) the reversed species have been separated under the name physa, fig. . other generic names have been given to other species. lines of growth. the concentric striæ or lines formed by the edges of the successive layers of shelly matter deposited by the animal by which it increases the shell. the outer edge of the aperture is always the last line of growth. linguiform. (_lingua_, tongue; _forma_, form.) tongue-shaped. lingula. lam. (dim. from _lingua_, tongue.) _fam._ brachiopoda, lam. palliobranchiata, bl.--_descr._ equivalve, oblong, depressed, thin, equilateral, gaping and pointed at the umbones, gaping and truncate or trilobate at the opposite extremities, attached by a fleshy pedicule fixed to the umbones.--_obs._ this is the only bivalve shell which is pedunculated, in which respect it constitutes a singular anomaly. the ancient writers, seeing the valves separate, placed it in their systems under the name patella unguis. there are several recent species found in the moluccas, and some fossils in sandy indurated marl, and in alluvium of suffolk. l. anatina, fig. , is so named from its resemblance to a duck's bill. lingulina. d'orb. a genus of microscopic foraminifera. linthuris. montf. conch. syst. . . a genus of microscopic foraminifera. lip. see labium and labrum. lippistes. montf. a genus of microscopic foraminifera. lithodomus. cuv. ([greek: lithos], _lithos_, stone; [greek: dôma], _doma_, house.) _fam._ mytilacea, lam.--_descr._ transverse, elongated, cylindrical, equivalve, with the extremities rounded, and the posterior extremity rostrated; umbones not prominent, terminal; hinge straight, destitute of teeth; ligament linear, most conspicuous within; muscular impressions two.--_obs._ the shells composing this genus differ from modiola, not only in the cylindrical form, but also in the circumstance from which the generic name is derived, i. e. of their living in stones. thus, while the form and structure of the shell bring it near the mytili or muscle shells, the habits of the animal cause it to approach the lithophagi, or rock-eating molluscs of lamarck. l. dactylus (fig. ,) is the mytilus lithophagus of ancient authors. litholepas. bl. ([greek: lithos], _lithos_, stone, [greek: lepas], _lepas_, rock.) de blainville's name for lithotrya, sow. lithophagidÆ. lam. ([greek: lithos], _lithos_, stone; [greek: phagô], _phago_, eat or gnaw.) a family of the conchifera dimyaria, lam. consisting of terebrating bivalves, gaping anteriorly, having no accessary valves; and containing the genera saxicava, petricola, venerupis, to which are added other genera enumerated in explanation of figures to . notwithstanding the numerous genera which have been created, i think that the most convenient arrangement will be to reduce them to two, thus-- . petricola, with distinct cardinal teeth, including, clothe, venerirupis and coralliophaga. fig. , , . . saxicava, without teeth, including biapholius, hiatella, sphænia, byssomya, and thracia. fig. to . lithotrya. g. b. sowerby. ([greek: lithos], _lithos_, stone; [greek: truo], _truo_, to bore through.) _fam._ pedunculated cirripedes, lam.--_descr._ eight unequal valves, forming a laterally compressed cone, the lower central valves being very minute; pedicle fleshy, scaly at the upper extremity; fixed at the base in a patelliform shelly support.--_obs._ this genus derives its name from the power possessed by the animal of making dwelling holes in stones or pieces of rock. the remarkable shelly cups at the base of the pedicle is regarded as analogous to the shelly base of the balanus, so that this genus would form an intermediate link between the sessile and pedunculated cirripedes of lamarck. fig. , l. dorsalis. west india islands. litiopa. ranz. _fam._ turbinacea, lam.--_descr._ "shell not very thick, horny, with a slight epidermis, rather transparent, conical, with whorls somewhat rounded; the last being larger than all the rest together; with the apex pointed, longitudinally grooved; aperture oval, larger anteriorly than posteriorly, with the lips disunited, the right lip simple, separated from the left by a rather indistinct notch, or a slight emargination in the contour. the left lip slightly reflected backwards, so as to form a kind of salient margin with the anterior extremity of the columella, which is united, rounded, arcuated and slightly truncated at the anterior."--_obs._ the molluscous animals, whose shells are thus described, are found in the mediterranean, and are remarkable for the power of suspending themselves from the sea-weed on which they live, by a thread resembling a spider's web. the general appearance of the shell presents a medium between phasianella and littorina, but it is apparently destitute of an operculum. littorina. fer. (_littus_, the sea-shore.) _fam._ turbinacea, lam.--_descr._ turbinated, thick; spire acuminated, consisting of few whorls, about one third of the axis in length; aperture entire, large, rounded anteriorly; outer lip thickened within, acute; columella rather flattened; operculum horny, spiral, with rapidly increasing volutions.--_obs._ the shells composing this genus are known from turbo and phasianella by the horny operculum; and from trochus, which has also a horny operculum, by the small number of the whorls. the littorinæ, among which may be enumerated the common periwinkle, are, as the name implies, found on sea shores, feeding upon seaweed, in all parts of the world. fig. , _l. vulgaris_. lituacea. bl. the second family of polythalamacea. bl. the shells are described as chambered, symmetrical, convolute in part of their extent, but constantly straight towards the termination. the genus spirula, which is admitted into this family, does not properly belong to it, any more than to the lituolæ of lamarck, in which it is also placed. it does not agree with the descriptions of either. this family partly corresponds with the "lituolées," lam. and contains the genera lituola, ichthyosarcolites, spirula, hamites and ammonoceras. lituacea. lam. a family of the order polythalamous cephalopoda, lam. containing the genus spirula, fig. . lituitus. montf. spirolina, lam. microscopic. lituola. lam. a genus of microscopic foraminifera. lituolÆ. lam. the third family of polythalamous cephalopoda, lam. the shells of which are described as partially spiral, the last whorl continuing in a straight line. the transverse septa which divide the chambers, are in general pierced by a siphon which breaks itself off before it reaches the succeeding septum. this family contains the genera of microscopic foraminifera lituola and spirolina. the genus spirula, also placed in this family, does not by any means agree with lamarck's definitions "the last whorl continuing in a straight line." lituus. humph. cyclostoma? lam. livid. (from _lividus_.) of a pale, dull, blue colour. the adjective is sometimes used as a specific name. _ex._ conus _lividus_, sanguinolaria _livida_. lobaria. schum. sanguinolaria rosea, lam. (fig. ) and other similar species. lobate or lobed. divided into parts. lobatula. fleming. a genus composed of two very minute species of chambered shells. serpula lobata and s. concamerata, mont. test. brit. . lomastoma. rafinesque. an imperfectly defined genus, probably belonging to the limnacea. longitudinal. lengthwise. longitudinal striæ, ribs, &c. are those which radiate from the apex and follow the spiral direction of the whorls, in spiral shells; and from the umbo to the ventral margin in bivalves. the term "decourantes" is employed by french conchologists. the bands in achatina, fig. , are longitudinal or spiral. loripedes. poli. a genus composed of species of lucina, auct. in which the lunules are not prominent. lotorium. montf. a genus composed of species of triton, auct. in which the aperture is effuse. t. lotorium, fig. . lottia. gray. patelloida, quoy and gaimard. lucerna. humph. a generic name applied to some species of helix included in de ferussac's sub-genus helicogena. lucernella. sw. a genus of "lucerninæ," sw. thus described: "teeth on both sides of the aperture; surface regularly and distinctly striated. circumference convex." lucidula. sw. a sub-genus of lucerna, humph. thus described: "aperture transverse, both lips much thickened and united; the outer with marginal obsolete teeth at the base; umbilicus closed. barbadensis, _lam._ no. . p. . fêr. moll. pl. , , , ." lucina. brug. _fam._ nymphacea, lam. conchacea, bl.--_descr._ equivalve, inequilateral, orbicular, lenticular, radiately striated; hinge with, generally, two minute cardinal teeth, which are sometimes nearly obsolete, and two lateral teeth, on each side of the umbo in one valve, one in the other; ligament external, partly hidden by the margins of the valves when closed. muscular impressions two in each valve, the anterior one produced into an elongated, ligulate band, the posterior short and semi-rotund; impression of the mantle not sinuated.--_obs._ the shells of this genus resemble amphidesma in general form, but are distinguished by the external ligament, the elongated muscular impression, and the want of a sinus in the palleal impression. east and west indies, and european shores. fig. , l. tigerina. lunulate. (_luna_, the moon, dim.) moon-shaped, having the form of a crescent. applied most frequently to muscular impressions. semilunar is sometimes used, perhaps with greater accuracy, to express the same shape. lunule. an impression on the anterior dorsal margin of some bivalve shells. the similar impression on the posterior dorsal margin is called the _escutcheon_. luponia. gray. a genus composed of species of cyprÆa, auct. which are described as having the anterior of the columellar lip crossed by several irregular ridges, without any distinct marginal ones, internally narrow, flat; the shell pear-shaped, smooth, or cross-ribbed. _ex._ c. algoensis, luponia algoensis, gray, fig. . lutraria. auct. (_lutum?_ mud.)--_fam._ mactracea, lam.--_descr._ thin, equivalve, inequilateral, transverse, oblong or ovate, gaping at both extremities; hinge with one double and sometimes one single cardinal tooth in each valve, and a triangular, oblique pit with a prominent margin, containing the ligament; muscular impressions distant; palleal impression having a large sinus.--_obs._ this genus differs from mactra in the entire absence or indistinctness of lateral teeth. fig. , l. papyracea. (ligula, leach.) fig. . l. solenoides. sandy and muddy shores. lutricola. bl. lutraria. lam. fig. , . lycophris. montf. a microscopic fossil described as resembling nummulites, but having a granulated surface. lymnadea. sw. a sub-genus of "mysca," turton, in the family of nayades, lam. thus described: "posterior hinge margin elevated and winged; the valves connate; the surface smooth. l. alata. _sw._ _ex._ conch. (fig. .) fragilis. _sw._ zool. ill. compressa, _lea._ am. tr. iii. pl. . f. ." sw. p. . lymnea. see limnea. lymneus. lam. see limneana. lyonsia. turt. inequivalve species of anatina, auct. which have no spoon-shaped cavity in the hinge, but an accessary piece. l. striata, fig. , . lyrodon. goldf. trigonia? maclurites. lesuour. journ. des scienc. nat. philad. t. . p. . pl. . fig. , . macoma. leach. venus tenuis, bl. and similar species, described as "clothed with an epidermis; striated, compressed, oval; the summits not very prominent; two bifid teeth upon the right valve and a single undivided one upon the left." macroditus. montf. lenticulina, bl. a genus of microscopic foraminifera. macrospira. guild. a genus composed of helix octona, auct. macrospira aperta, guild. macrostomata. lam. ([greek: makros], _macros_, long; [greek: stoma], _stoma_, mouth.) a family belonging to the first section of the order trachelipoda, the shells belonging to which are described as haliotoid or ear shaped, with a very large aperture, destitute of an operculum. this family contains the following genera, which maybe thus distinguished. . velutina. globose, with velvety epidermis. fig. . . stomatia. ear-shaped; pearly within; including stomatella. fig. , . . sigaretus. the same, not pearly; including _cryptostoma_. fig. . . coriocella. the same, thin, transparent. . haliotis. the same, not thin, nor transparent; with holes; including _padollus_. fig. , . . scissurella. heliciform, with a slit near the aperture. fig. . . pleurotomaria. trochiform, with a slit at the edge of the aperture. fig. . mactra. auct. (_mactra_, a kneading trough.) _fam._ mactracea, lam. conchacea, bl.--_descr._ usually thin, equivalve, sub-equilateral, sub-trigonal, slightly gaping at the extremities; hinge with one cardinal tooth, divided into two parts, diverging from the umbo, with sometimes a very small laminar tooth close to its side; a deep triangular pit near the centre, containing the cartilage; one long, lateral tooth on each side of the umbo in one valve, received between two in the other; muscular impressions two, lateral; palleal impression with a small sinus.--_obs._ this genus contains many species of beautiful shells found in various parts of the world, some are common in britain. fossil species are not numerous, they occur in the tertiary strata. fig. to . mactracea. lam. a family of the order conchifera dimyaria, lam. sect. tenuipedes. the cartilage placed in a trigonal pit with a small external ligament. the genera may be thus distinguished. . lutraria. no lateral teeth, shell gaping. the short species constitute the genus _ligula_. fig. , . . mactra. lateral teeth, shell closed. this genus has been divided into mactra, mulinia, schizodesma and spisula, by mr. gray. fig. to . . gnathodon. teeth serrated, thick, one angular. fig. . . crassatella. shell thick, lateral teeth. fig. . . amphidesma. a distinct external ligament, internal ligament oblique. fig. . . erycina. a short tooth on each side of the cartilaginous pit in each valve. including mesodesma. fig. . . ungulina. ligament flat, divided. fig. . maculated. (from _macula_, a spot.) spotted or patched. this term is applied by conchological writers, to those shells which are coloured in spots or small patches. in the same sense it is also used as a specific name. as for instance, cytherea maculata, fig. , c. and hippopus maculatus, fig. . magas. sow. ([greek: magas], _magas_, a board, a deck.) _fam._ brachiopoda, lam.--_descr._ equilateral, inequivalve; one valve convex, with a triangular area, divided by an angular sinus in the centre; the other valve flat, with a straight hinge line and two small projections; a partial longitudinal septum, with appendages attached to the hinge within. differing from terebratula in having a triangular disc, and not a circular perforation. magas pumilus, fig. . fossil in chalk. magilus. montf. _fam._ cricostomata, bl. serpulacea, lam.--_descr._ thick, tubular, irregular, contorted; rounded above, keeled beneath, free; apicial extremity convolute, heliciform, ovate or sub-globose; aperture elliptical.--_obs._ this shell when in a young state presents the characteristics of a regularly formed spiral univalve, living in holes in madrepores. as the madrepore increases in bulk, the animal gives an eccentric course to the shell, in order to have its aperture even with the surface, and leaving the nucleus or young shell behind, fills it up with calcareous matter to reside in the open extremity of the tube. fig. , . red sea and mauritius. malacota. schum. otion. leach. malacozoa. bl. ([greek: malakos], _malacos_, soft; [greek: zôon], _zoon_, animal.) the type or general appellative in de blainville's system, including all molluscous animals, excepting those with multivalve shells. maldania. lam. the second family of the order annelides sedentaria. the only genus of shells described in this family is dentalium, fig. , to which may be added pharetrium, könig. fig. . it is doubtful however whether the latter do not belong to an unknown genus of pteropodous mollusca. malea. valenciennes. a genus composed of dolium latilabrum, kiener, and other similar species. malentozoa. bl. ([greek: malakos], _malacos_, soft; [greek: en], _in_, [greek: temnô], _temno_, cut; [greek: zôon], _zoon_, animal.) or articulated mollusca. the sub-type in de blainville's system, comprehending those with multivalve shells. malleacea. lam. a family belonging to the order of conchifera monomyaria. containing the following genera of irregular pearly bivalves. . avicula. hinge linear, simple, including _meleagrina_. fig. , . . perna. hinge with linear grooves, including _pulvinites_. fig. , . . gervillia. shaped like modiola, with irregular grooves. fig. . . crenatula. hinge with a series of pits. fig. . . catillus. like perna, but more regular and convex. fig. . . malleus. a triangular disc on the hinge, and two auricles. fig. . malleus. auct. (_malleus_, a hammer.) _fam._ malleacea, lam. margaritacea, bl.--_descr._ equivalve, inequilateral, foliaceous, trilobate, undulated, irregular, attached by a byssus passing through a sinus in one valve; hinge rectilinear, lengthened by two auricles; with a small disc under the umbones, containing the ligament, and a groove containing the cartilage; muscular impressions one in each valve, large, uniform, and one or two others extremely minute.--_obs._ malleus vulgaris, the type of this genus, is a most singular shell, commonly called the "hammer oyster," from the peculiarity of its shape. it belongs to the linnæan genus ostrea, from which it differs in being attached by a byssus. fig. , m. vulgaris. tropical. mamillaria. sw. a sub-genus of natica, corresponding with polinices of montfort, having the spire small and the umbilicus filled. _ex._ natica mamilla, auct. fig. . mammillated. (_mammula_, a little teat.) a term applied to the apex of a shell when it is rounded like a teat. _ex._ voluta vespertilio, fig. . margarita. leach. (_margarita_, a pearl.) a genus of small shells resembling the genus trochus, from which it differs in having an operculum consisting of few whorls. m. tæniata, fig. . mr. g. b. sowerby, sen. has enumerated species in a list accompanying the figures published by the author of this manual in nos. to of his conchological illustrations. margaritacea. bl. the third family of lamellibranchiata, bl. the shells belonging to it are described as irregular, inequivalve, inequilateral, black or horny without, pearly within; hinge auriculated, scarcely developed, and without teeth. the ligament is variable and there is a large sub-central muscular impression. this family contains the genera vulsella, malleus, pinna, crenatula, inoceramus, catillus, pulvinites, gervillia and avicula. margaritaceous. (_margarita_, a pearl.) pearly. margaritana. schum. a sub-genus of uniones, composed of species having "one cardinal tooth." alasmodon, say. mya margaritifera, linn. margaritiferous. (_margarita_, pearl; _fero_, to bear.) pearl-bearing. applied to shells which form pearls; as meleagrina margaritifera, or pearl-bearing oyster. marginal. near the margin or edge. marginated. (_margo_, edge.) having an edge or border thicker than the rest of the shell, from which circumstance the little genus marginella derives its name. marginella. (a little rim or border.) _fam._ columellaria, lam. angyostomata, bl.--_descr._ ovate, smooth, shining, with a short, sometimes hidden spire; aperture narrow, emarginated; columella with several oblique folds; outer lip neatly reflected.--_obs._ this genus of pretty little shells differs from voluta, in the reflection of the outer lip. the animal covers the greater part of the shell with the mantle, and by continually depositing vitreous matter gives it a bright polish, which, together with the delicately neat arrangement of colours in most species, renders them exceedingly beautiful. the marginellæ are marine and tropical. a few fossil species are found in the calc-grossier. fig. . m. glabella. glabella, sw. marginulina. d'orb. a genus of microscopic foraminifera. marine conchacea. see conchacea. marine testacea. those shell-fish which inhabit seas, lakes, &c. of salt water, in distinction from the _aquatic_ testacea, or those which are found in rivers, ponds or stagnant pools of fresh water: and also from the _land_ testacea, which live on land and breathe air. the great proportion of shells belong to the former class, those of the latter two classes being limited in their number, and in the genera to which they belong. marinula. king. a genus of small shells resembling auricula and pedipes, described as "ovate, sub-solid, with aperture ovate entire; columella bidentate, uniplicated towards the base, with large sub-remote teeth; the largest uppermost; no operculum." marmarostoma. sw. a genus of "trochidæ," sw. thus described: "umbilicus deep; spire of few whorls, much depressed, and obtuse; inner lip obsolete; base even more produced than in _senectus_, but never distinctly channeled. m. versicolor. mont. . f. , , undulata. chem. . f. , ," sw. p. . marpessa. gray. a sub-genus of clausilia, c. bidens, &c. auct. gray's turton, p. . martesia. leach. a genus composed of those species of pholas, auct. which are described as short, cuneiform, nearly closed at both extremities, having several accessary pieces on the middle of the back, and two marginal, lower down. measurement. the most approved method of stating the measurements of various kinds of shells is as follows: _symmetrical convolute univalves_, the length is from anterior to posterior; the depth from ventral to dorsal; the breadth, from side to side of the aperture. of _symmetrical conical univalves_, length, from front to back; breadth from side to side; depth from apex to base. of _spiral univalves_, length, from apex to anterior of the columella or axis of the shell; breadth, across from the outer lip to the opposite side. of _non-symmetrical bivalves_, the length is from the anterior to the posterior margin; breadth, from the greatest convexity of one valve to the corresponding part of the other; depth, from the ventral to the dorsal margin. megadesma. bowd. ([greek: megas], _megas_, great; [greek: desma], _desma_, ligament.) potamophila, sow. galathÆa, lam. megadomus. sw. a sub-genus of unio, thus described: "only one lateral tooth in each valve; cardinal teeth two; posterior hinge margin winged. m. gigas, _sw._" sw. p. . megalodon. sow. ([greek: megas], _megas_, great; [greek: odos], _odos_, tooth.) _fam._ cardiacea, lam.--_descr._ equivalve, longitudinal, acuminated at the umbones, thick; hinge forming an incrassated septum across the cavity of the shell, with a large bifid tooth in the right valve, and one irregular and one pointed in the left; ligament long, external.--_obs._ the general form, the thickened hinge reaching across the cavity of the valve and the terminal umbones serve to distinguish this genus from cardita, to which, however, it is nearly allied. m. cucullatus, fig. . megalomastoma. guild. a sub-genus of cyclostoma, thus described: "cylindrical, resembling _pupa_, but has a horny operculum; spire not thickened; teeth or fold on the pillar none, flavula _sw._ en. méth. . f. , brunnea _guild._ (_fig. . g. h. ._)" sw. p. . mr. gray applies the name to those species which have "a groove or ridge in front of the mouth near the pillar." megarima. rafinesque. a genus proposed to include species of terebratula, auct. which are smooth and nearly equivalve. t. lævis, t. crassa, t. truncula. megaspira. lea. ([greek: megas], _megas_, great, and spire.) m. ruschenbergiana, (fig. ) is a pupiform land shell remarkable for the length of its spire, which consists of no less than twenty-five close set, narrow, gradually increasing whorls. the outer lip is simple, slightly thickened; the inner lip has a tooth on the body-whorl, and two folds on the columella. only one species of this singular shell is known. megatrema. leach. a genus composed of those species of pyrgoma, auct. which have a large aperture. fig. . melacantha. sw. a sub-genus of melania. sw. p. . melafusus. sw. a sub-genus of melanopsis. sw. p. . melampus. montf. conovulum, lam. a genus composed of species of auricula, auct. of a conical form. a. conoidalis, fig. . melania. auct. ([greek: melas], _melas_, black.) _fam._ melaniens, lam. ellipsostomata, bl.--_descr._ turrited; spire generally elongated, acute; aperture entire, oval or oblong, pointed at the posterior extremity, rounded anteriorly, with a kind of indistinct canal or sinuosity: epidermis thick, generally black.--_obs._ in common with other fresh-water shells, the melaniæ are frequently found with corroded apices. this genus is known from melanopsis by the absence of the notch at the anterior part of the aperture. the melaniæ occur in rivers of warm climates. the fossil species are frequent in upper marine formations. fig. , m. subulata. melaniana. lam. (melaniens.) a family belonging to the first section of the order trachelipoda. the genera contained in it maybe distinguished as follows. . melanopsis. aperture notched; columellar lip thickened above; including _pirena_. fig. , . . melania. aperture not notched; columellar lip not thickened; including _auculosa_, _pasithæa_, _io_. fig. , , . melanithes. sw. a sub-genus of melanopsis. sw. p. . melanoides. olivier. melanopsis. fer. melanopsis. fer. _fam._ melaniana, lam. entomostomata, bl.--_descr._ oval or oblong, fusiform; spire acute, sometimes elongated; aperture oblong or oval, pyriform, with a distinct notch at the anterior extremity; columella tortuous, callous, thickened at the extremity near the spire; epidermis thick, horny, generally black. subtropical.--_obs._ this description includes the two first species of the genus pirena, lam. the melanopsides are known from the melaniæ by the notch in the aperture. fig. . m. costata. melas. montf. melania, auct. melatoma. sw. a sub-genus of melanopsis. sw. p. . meleagrina. lam. margarita. a genus composed of the pearl oyster and similar species, separated from avicula on account of the roundness of their general form, but re-united by sowerby. for generic characters, see avicula. fig. . m. margaritifera. meleagris. montf. turbo pica, auct. and similar species, having the aperture oblique, the columella gliding imperceptibly into the outer lip, and having an umbilicus. melina. schum. perna, auct. melo. brod. (_melo_, a melon.) _fam._ columellaria, lam.--_descr._ light, ventricose, oval, with a light greenish brown epidermis, spire short, papillary, regular, sometimes hidden by the last whorl; aperture large, nearly as long as the whole shell, emarginated anteriorly; outer lip thin; columella slightly curved, with four or five laminar, oblique, prominent plaits.--_obs._ the genus melo has been separated from _voluta_ principally on account of the largeness of the aperture, the lightness of the shell and the thinness of the outer lip. melo differs from cymba in the regularity of the spiral apex, and in the greater rotundity of the shell. the melons are beautifully coloured large shells, found in the seas of the old world. the melo indicus has a certain resemblance to a melon. fig. . m. Æthiopicus. melonia or melonites. a genus of microscopic foraminifera. mercenaria. schum. venus mercenaria, auct. the money shell which passes current for cash, under the name "wampum," among the north american indians. meretrix. lam. original name for cytherea, lam. meroe. schum. cytherea meroe, sulcata, scripta, hians, auct. and similar species. fig. , a. mesodesma. desh. erycina, lam. according to g. b. sowerby. mesomphyx. rafinesque. a genus proposed to be separated from helix, auct. microtoma. sw. a genus of "purpurinæ," sw. thus described, "pillar very broad and curving inwards; aperture effuse; the notch at the base small and nearly obsolete; spire very short, patula. mart. . f. , . persica. en. méth. . f. . unicolor. _sw._ chem. f. . sw. p. ." purpura persica. fig. . miliola. lam. a genus of microscopic foraminifera. misilus. montf. a genus of microscopic foraminifera. mitra. lam. (_mitre._) _fam._ columellaria, lam. angyostomata; bl.--_descr._ oblong, thick, covered with a light brown epidermis; spire long, turrited, acute; aperture emarginated anteriorly; outer lip thickened; columella with several oblique, thick plaits.--_obs._ the pretty small shells composing this genus differ from marginella, not only in general form, but in the outer lip not being reflected. some species of voluta, of a more elongated shape than the rest, present a near approach to the most ventricose of the mitræ. the apex of mitra, however, is always acute, while that of voluta is generally papillary. the aperture of the former is narrow and the inner lip thickened, the contrary being the case with the latter. the shells of this genus are varied in colouring which is generally rich; and also in form, some being angulated, some plicated, some coronated and others smooth. the species are mostly tropical; very few occur so far north as the mediterranean. fossil species are numerous in the eocene beds. fig. . m. plicaria. fig. . conohelix marmorata, sw. mitrella. sw. a genus consisting of mitra fissurella, casta, olivæformis, and similar species, described as "rather small; olive-shaped; unequally fusiform; always smooth and polished, and sometimes covered with an epidermis; base obtuse and effuse; spire nearly or quite equal to the aperture; plaits of the pillar few, oblique, and extending beyond the aperture, which is smooth internally." sw. p. . m. fissurata, e. m. . f. . olivarii, f. . dactylus. . f. . _ex._ mitra bicolor. mitreola. sw. a genus of "mitranæ," sw. thus described: "small; unequally fusiform; the base obtuse; inner lip, typically thickened, inflected, and either toothed or tuberculated; plaits on the pillar distinct, the inferior largest; tip of the spire sometimes papillary; aperture without either striæ or groove." sw. p. , m. monodonta, m. terebellum. zool. illustr. ii. . f. . f. . modiola. lam. (_modiola_, a little measure.) _fam._ mytilacea, lam.--_descr._ equivalve oblique, cuneiform, inequilateral, thin, with the anterior side short and narrow, slightly gaping to admit the passage of a byssus, and the posterior side elongated, broad, sub-quadrate; hinge thin, toothless, rectilinear, with a long, partly external ligament; muscular impressions two in each valve; palleal impression irregular, not sinuated.--_obs._ this genus differs from mytilus, to which the common muscle belongs, in the anterior margin being rounded out beyond the umbo, which in mytilus is terminal. the lithodomi may be known from this genus by their cylindrical form. fig. , m. tulipa. mollusca. (from _mollis_, soft.) the twelfth class of invertebrated animals with univalve shells or none; divided into the following orders: pteropoda, gasteropoda, trachelipoda, cephalopoda, heteropoda, fig. to . the term mollusca is also used in a general sense to include the classes conchifera and mollusca of lamarck, corresponding with the type malacozoa of de blainville. money cowry. cypræa moneta, which passes current in some parts of africa and the east indies. monilea. sw. a sub-genus of monodonta. sw. p. . monoceros. ([greek: monos], _monos_, single; [greek: keras], _ceras_, horn.) _fam._ purpurifera, lam.--_descr._ ovate, thick, covered with a brown epidermis; spire short, consisting of few whorls; aperture emarginated anteriorly; columella rather flat; outer lip thick, with a prominent tooth near the extremity.--_obs._ this genus resembles purpura, in every respect, except in having the tooth from which the name is derived. a catalogue of species by mr. sowerby, sen. is published with figures of , in parts to of the conchological illustrations by the author. the species belong to the south american coasts of the pacific ocean. monocondylÆa. d'orb. a sub-genus of uniones, described as equivalve, inequilateral, sub-rotund or angulated; hinge consisting of a large, obtuse, round cardinal tooth in each valve, with no lateral teeth. monocondylæ (unio) paraguayana, d'orb. fig. . monodonta. lam. odontis, sow. a genus separated from trochus, auct. on account of the tooth or notch with which the columella abruptly terminates. m. labeo, fig. . monoica. bl. the second sub-class of the class paracephalophora, bl. divided into the orders pulmobranchiata, chismobranchiata, monopleurobranchiata, in the first section; and aporobranchiata, polybranchiata, cyclobranchiata, inferobranchiata, and nucleobranchiata, in the second. monomyaria. lam. ([greek: monos], _monos_, single; [greek: muon], _myon_, muscle.) the second order of conchifera, consisting of those bivalve shells which have but _one_ principal muscular impression in each valve. the monomyaria are thus divided: first section, containing the families tridacnacea, mytilacea, malleacea; second section, containing the families pectinides, ostracea; third section, containing the families rudistes, brachiopoda. monopleurobranchiata. bl. the second order of the first section of paracephalophora monoica. bl. the animals are described as having the lungs branched, situated at the right side of the body and covered more or less completely by the operculiform mantle, in which there is sometimes enveloped either a flat or a more or less involute shell, with a large entire aperture. they have either rudimentary or auricular tentacula, or none. this order, which includes mollusca with haliotoid or patelliform shells, is divided into the following families: _fam._ . subaplysiacea; . aplysiacea; . patelloidea; . acera. monoptygma. lea. a genus of small shells resembling tornatella, but having a strong, oblique fold in the centre of the columellar lip. m. elegans, fig. . monothalamia. ([greek: monos], _monos_, single; [greek: thalamos], _thalamos_, chamber.) the second division of cephalopoda, lam. containing only one genus, namely argonauta. monothyra. a term used by aristotle to designate spiral univalves. monotigma. gray. a genus founded on the species represented fig. . it is a turrited shell, but we are unacquainted with the characters of the genus. morio. montf. cassidaria, auct. c. echinophora, fig. . mother of pearl. this beautiful substance, which is so much resorted to for ornamental purposes, constitutes the thickened coating of the internal surface of the shell named by scientific collectors, meleagrina margaritifera, commonly called the pearl oyster, a young specimen of which is figured ( ) in our plates. the reason why this substance is called mother-of-pearl is that the true pearls are produced from its surface. they arise principally from accident or disease, and are sometimes artificially produced by pricking through the outside of the shell while the animal is living. the animal is allowed to live until it has formed a pearl over the wounded part. moulinsia. grateloup. pupina, vignard. a genus of small land shells with enamelled surface and spiral operculum. see pupina. mouretia. gray. "_gadin_," adanson. a genus of patelliform shells, described as differing from siphonaria (the original mouretia of adanson) in the situation of the siphon, which in mouretia is close to the place where the muscular impression is interrupted to leave a space for the head; while in siphonaria it is nearly half way between the anterior and posterior ends of the shell. mouth. the aperture or opening of univalve shells. mulinia. gray. a genus composed of species of mactra, auct. described as having the ligament (properly so called) internal, and lateral teeth simple. _ex._ fig. . m. bicolor; mactra, auct. mulleria. fer. _fam._ ostracea, lam.--_descr._ irregular, subquadrate, inequivalve, inequilateral, foliaceous, attached, pearly within, green, horny without; hinge irregular, with a partly external ligament, passing to the interior, through a sort of sinus.--_obs._ this remarkable shell resembles etheria in general form and appearance, but is distinguished by having only one muscular impression. it is so rare that, although not very beautiful, a specimen has been known to produce £ . at a sale. fig. . multilocular. many chambered. multispiral. (_multus_, many, _spira_, spire.) a term applied to a shell when the spire consists of numerous whorls; or to an operculum of numerous volutions. multivalve. (_multus_, many; _valva_, valve.) consisting of numerous valves. there are three kinds of multivalve shells: st. those in which the valves are arranged in pairs, and produce a flattened figure, as pedunculated cirripedes, fig. to ; nd. those in which they are arranged circularly, as sessile cirripedes, the valves of which are of two kinds; the _opercular_, consisting of several valves, which close the aperture, and the _parietal_, consisting of those which surround the body of the animal in a circular form, fig. to . rd. those in which they are arranged in a straight line, as chiton, fig. . murex. auct. (_a sharp rock._) _fam._ canalifera, lam. siphonostoma, bl.--_descr._ turrited, ventricose, thick, with three or more longitudinal, continuous, branched, spinose or fringed varices; spire prominent, acute; aperture oval, terminating in a posterior, partly closed canal, outer lip varicose, inner lip smooth, laminar; operculum horny, concentric, pointed.--_obs._ this genus contains some of the most exquisitely beautiful shells in existence, the richness of their colouring, the ramifications of their varices, would render most species the finest possible subject for the exercise of the painter's art in still life. the most remarkable are the rosebud murex, with its pink-tipt fringes, the venus comb, with its long rows of parallel spines; the ducal murex, the royal murex, and many others, which are much sought after by collectors. murex may be distinguished from triton by the continuity of the varices, which follow each other in a tortuous direction on the spire. the ranellæ have only two rows of varices, and have a posterior as well as anterior canal; while murices have three or more varices, and only one canal. the genus typhis consists of several small species resembling murex in every respect, excepting that of having a tubular opening on the upper part of the whorl between each varix. see typhis. the most beautiful murices are brought from tropical climates. fig. , . muricanthus. sw. a sub-genus of murex, thus described: "varices numerous, foliated; spire short; margin of the outer lip with a prominent tooth near the base; radix. _sw._ zool. ill. nd series. pl. , melanomathus. en. méth. . f. ." sw. p. . the latter of the two species quoted, however, does not agree with the description, having no prominent tooth on the margin of the outer lip. muricated. (_muricatus._) having sharp points or prickles. muricidea. sw. a genus of "muricinæ," sw. thus described, "spire more produced, as long or longer than the body whorl; varices numerous; no internal channel at the top of the aperture." sw. p. , and consisting of the following incongruous species, "lamellosa. chem. f. , . magellanica. en. m. . f. . peruviana. ib. f. . senticosa, ib. f. . scaber. en. méth. . f. . hexagona. ib. . f. . erinacea. mart. f. ." sw. p. . muscular impressions are the marks or areas formed on the interior surface of shells by the muscular fibres which attach the animals to them. lamarck has divided his conchifera into two kinds: st. monomyaria, those which have but one adductor muscle, and consequently have but one impression in each valve, as the common oyster, fig. ; nd. the dimyaria, those which have two, and consequently have two impressions in each valve. there are other smaller impressions in some shells besides the principal. the palleal impression is a mark or scar passing near the margin of the shell. see introduction. mya. auct. _fam._ myaria, lam. pyloridea, bl.--_descr._ transverse, oval, thick, gaping at both extremities, rounded anteriorly, acuminated posteriorly; hinge with one large, dilate, compressed tooth in one valve, and a suture in the other, containing the cartilage; muscular impressions two, distant, large, irregular; palleal impression with a large sinus.--_obs._ mya may be known by the large, prominent, broad tooth in one valve. in anatina there is one in each valve, and, in lyonsia, accessory pieces. lutraria has cardinal teeth and a ligamentary pit. few species of mya are known. they belong to the northern hemisphere. m. truncata, fig. . mycetopoda or mycetopus. d'orb. _fam._ nayades, lam.--_descr._ shell elongated, soleniform, inequivalve, inequilateral, gaping anteriorly; muscular impressions very complex.--_obs._ these shells are said to terebrate like pholas. fig. . m. solenoides. myaria. lam. a family belonging to lamarck's order conchifera dimyaria. containing the following genera: . anatina. ligament in a spoon-shaped prominence on the hinge of each valve, shell thin. fig. . . mya. spoon-shaped prominence in one valve; shell thick. fig. . . anatinella. a spoon-shaped process in both valves. fig. . . lyonsia. an internal bony appendage on the hinge. fig. , . . myochama. flat valve attached, a bony appendage on the hinge. fig. . . cleidothÆrus. deep valve attached, a bony appendage. fig. , . . cumingia. ligamentary pit in both valves, spoon-shaped. fig. . myochama. stutch. (_mya_ and _chama_.) _fam._ myaria, lam.--_descr._ inequivalve, irregular, attached, subequilateral; attached valve flat, with two marginal, diverging teeth, and one end of a little testaceous appendage fixed between them by a horny cartilage; free valve convex, with umbo incurved and two very minute, diverging teeth, between which the other end of the testaceous appendage is placed; external surface of both valves conforming to the grooves or undulations of the shell to which the specimen is attached; muscular impressions two in each valve; palleal impressions with a short sinus.--_obs._ this new genus, of which only one species is known, the m. anomioides from new south wales, differs from anomia and anatina in being attached by the surface of one of the valves, from which circumstance the word chama is added to its name; the little testaceous appendage bringing it near the myariæ. fig. , m. anomioides. myoconcha. sow. (_mya_ and _concha_.) _fam._ cardiacea, lam.--_descr._ oval, equivalve, oblique; umbones terminal; ventral margin rounded; hinge with an external ligament, and one oblique, elongated tooth in the left valve; impression of the mantle not sinuated.--_obs._ the fossil genus has the general form of mytilus or modiola, but the hinge of the conchæ generally. myopara. lea. (_myoparo_, a piratical oar-galley.) _fam._ arcacea, lam. a genus founded on a minute fossil bivalve shell, somewhat resembling isocardia in form, but having a series of teeth placed on each side of the umbones. m. costatus, fig. . myristica. sw. a genus of "pyrulinæ," sw. thus described: "sub-pyriform; spire strong, spiny, or tuberculated, nearly as long as the base; umbilicus either partially or entirely concealed; inner lip vitreous, thin; the outer with an internal and ascending canal; the basal channel wide. hippocastanea. en. m. . f. . lineata, ib. f. . melongena. en. méth. . f. . nodosa. chem. . ." sw. p. . _ex._ p. melongena, fig. myrtea. turt. venus spinifera, auct. lucina spinifera, nonnull. the shells of this genus are described as "oval, triangular, equivalve, nearly equilateral, closed. hinge of one valve with a single tooth, and lateral one on each side; of the other valve with two teeth, the lateral ones obscure. ligament external." british channel and mediterranean. mysca. turt. a genus composed of species of unio, auct. which are distinguished by having "strong, transverse, notched, cardinal and long lateral teeth." unio pictorum. mysia. leach. a genus composed of tellina rotundata, montagu and other similar species. mytilacea. bl. the fourth family of lamellibranchiata, bl. the shells are described as regular, equivalve, frequently with a thick, horny epidermis. a toothless hinge and a linear ligament. this family contains the genera mytilus and pinna. mytilacea. lam. a family belonging to the first section of conchifera monomyaria, lam. described as having the ligament partly interior, occupying the greater part of the hinge line, which is straight. the shell is rarely foliaceous. the mytilaceæ cannot easily be confounded with the malleaceæ, because the former are generally regular and the latter are irregular, and have a thick internal coating of pearl, beyond which the external coating extends. the genera may be thus distinguished: . mytilus. umbones terminating in a point. fig. . . dreissina. the same, with a septiform plate. fig. . . modiola. anterior margin rounded beyond the umbones. fig. . . pinna. open at the posterior extremity. fig. . . lithodomus. cylindrical, living in holes. fig. . mytilus. auct. _fam._ mytilacea. lam.--_descr._ equivalve, cuneiform, oblique, smooth, with umbones terminal, pointed, and posterior side broad, rounded; hinge linear, with a long, partly internal ligament; muscular impressions two in each valve, that on the posterior side large, irregular; that on the anterior small; palleal impression irregular.--_obs._ the linnean genus mytilus included the modiolæ, which differ from the mytili in the rounded anterior side; and the pinnæ, which are large shells, gaping at the posterior extremity. m. achatinus, fig. . nÆara. gray. a genus composed of anatina longirostrum, lam. and other similar species. naia. sw. a sub-genus of castalia, lam. thus described: "oval, cardinal teeth beneath the bosses, and deeply sulcated, c. corrugata. _lam._ en. méth. . f. , picta. _sw._ en. méth. . f. ." sw. p. . naninia. gray. a genus composed of the planorbicular species of helix, with large umbilici, and outer lip thin, included in the sub-genus helicella, fer. _ex._ h. citrina, fig. . nassa. lam. a genus of small shells united to buccinum by some authors, but separated by others on account of the little tooth-like projection terminating the columella. n. arcularia, fig. . natica. brug. _fam._ neritacea, lam. hemicyclostomata, bl.--_descr._ globose, thick, generally smooth; spire short, pointed, with few volutions; aperture semilunar, entire; outer lip thin; columellar lip oblique, nearly straight, callous; umbilicus with a spiral callosity, terminating behind the columella, and sometimes filling up the cavity; operculum shelly in some species, horny in others; epidermis thin, light, semitransparent.--_obs._ the straight, callous, smooth edge of the columella and the callosity serve to distinguish this genus from nerita, neritina, neritopsis and helix. fig. , . naticaria. sw. a sub-genus of natica, thus described: "oval; convex above; umbilicus small, open, placed very near the top of the aperture; inner lip reflected; small. n. melanostoma, mart. . f. , . cancellata, _sw._ ib. . f. . bifasciata, griff. cuv. . f. ." sw. p. . naticella. guild. a sub-genus of natica, thus described: "operculum horny; shell globose, but generally depressed; umbilicus nearly filled up by a vitreous deposition of the inner lip; spire obtuse. n. aurantia. mart. . f. , ." sw. p. . navicella. lam. (_a little ship._) _fam._ neritacea, lam. hemicyclostomata, bl.--_descr._ transversely oval, symmetrical, smooth; aperture entire, oval; dorsal surface convex; outer lip thin; inner lip flat, straight edged; spread over the front surface of the body whorl, and sometimes hiding the apex; apex incurved; operculum testaceous, flat, sub-quadrate, with a lateral articulation.--_obs_. this well known genus, of which there are several species, is named cimber by montfort. the shells are brought from india, the isle of france and the moluccas. fig. , n. elliptica. nautellipsites. parkinson. a generic name proposed to include such species of nautilus as have been compressed, so as to assume an oval instead of a round form. the genus ellipsolites of de montfort consists of species of ammonites similarly deformed. nautilacea. bl. the fifth family of polythalamacea, bl. the shells of which are described as more or less discoidal, compressed, symmetrically convolute; the last whorl much longer than the others; which are entirely hidden beneath it and advancing beyond the last but one, so as constantly to form a large oval aperture, which is always, however, modified by the last whorl. the septa are united in the greater number of instances and pierced by one or more (?) siphons. this family contains the genera orbulites, nautilus, polystomella and lenticulina. nautilacea. lam. the sixth family of polythalamous cephalopoda, lam. containing the genera discorbites, siderolites, polystomella, vorticialis, nummulites, nautilus. to these may be added simplegas and endosiphonites. fig. to . nautilus. auct. (_a little boat._) _fam._ nautilacea, lam. and bl.--_descr._ convolute, discoid, chambered, symmetrical; spire partly or entirely concealed by the last whorl; aperture modified by the last whorl, wide, sinuated on the dorsal margin; interior surface pearly; septa dividing the chambers simple; siphon discontinuous.--_obs._ the shell named nautilus by pliny is the argonauta of modern authors, a thin shell, not chambered. the nautili are known from the ammonites by the septa being simple, not sinuated as in the latter genus, and in general the volutions of the spire are not visible. three or four species are known inhabitants of the pacific ocean and australian ocean. the fossil species are found in the tertiary, and also in the secondary strata, as low down as the mountain limestone. n. pompilius, frontispiece. nayades. lam. a family of the order conchifera dimyaria, lam. described as containing fresh-water bivalve shells, with or without teeth on the hinge. they are all pearly within, and have a thick, rather smooth epidermis without. this family contains a great variety of shells, which have been separated into an immense number of genera, but which g. b. sowerby, sen. gives very good reasons for uniting under one generic name. the most generally received distinctions are as follows: . castalia. two cardinal, one lateral, ribbed teeth. this genus is removed from the family of trigonacea. fig. . . unio. teeth various. fig. , , , , , , . . hyria. trigonal, alated. fig. , . . anodon. no teeth. fig. . . iridina. hinge crenated. fig. . nectopoda. bl. the first family nucleobranchiata, bl. containing the genera carinaria and firola; the latter is not a shell. nematopoda. bl. the first class of the sub-type malentozoa, bl. containing all the mollusca with multivalve shells, except chiton, and divided into the families lepadicea and balanidea, corresponding with lamarck's sessile and pedunculated cirripedes, and with the linnæan genus lepas. nematura. benson. _fam._ turbinacea, lam.--_descr._ thin, nearly oval, somewhat compressed from back to front; spire acute, consisting of few rounded whorls; last whorl large, but contracted near the aperture; aperture small, oblique, rounded anteriorly; peritreme continuous, thin; operculum spiral, horny, with few volutions.--_obs._ the distinguishing character of this genus is the contraction of the last whorl near the aperture, in which respect it is nearly resembled by the shell called cyclostoma lucidum. two recent and one fossil species, all very minute, are described by sowerby in loudon's magazine of natural history, new series. fig. . nerinea. defr. _fam._ canalifera, lam.--_descr._ turrited, oblong, sub-canaliculated, consisting of numerous whorls; aperture with a strong fold on the columella, one on the outer lip, and one on the inner lip at the edge of the body whorl.--_obs._ this genus is only found in a fossil state usually in the oolitic beds, it is not resembled by any other; the strong, prominent folds on the three upper angles of the subquadrate aperture present a singular appearance in a section. one species has been named n. hieroglyphus. we give n. goodhallii, fig. . nerita. auct. _fam._ neritacea, lam. hemicyclostomata, bl.--_descr._ smooth or ribbed, semiglobose; spire short, sometimes flat, consisting of few volutions; aperture large, semilunar; outer lip thick, entire; inner lip thickened, dentated at the edge, spread over the body whorl, forming a flattened disc; operculum shelly, spiral, with an appendage by which it is locked under the sharp edge of the columella.--_obs._ these marine shells are known from neritina by the thickness of the shell and the want of the thick, horny, dark coloured epidermis; from natica by the flat area produced by the spreading of the thickened columellar lip. n. peloronta, fig. . n. polita, fig. . neritacea. lam. a family of the first order of trachelipoda, lam. containing the following genera: . navicella. apex terminal, not spiral; inner lip septiform. fig. . . nerita. columellar lip septiform, edge with distinct teeth; shell thick. fig. . . neritina. shell thin; columellar lip septiform, edge denticulated; generally a thick, dark coloured epidermis. fig. to . . natica. having an umbilicus behind the columellar lip, with a spiral callosity. fig. , . . neritopsis. edge of the columellar lip with a deep notch. fig. . . pileolus. patelliform; apex central; columellar lip septiform, leaving the aperture small. fig. . . janthina. columellar lip linear; aperture angulated. fig. . neritina. lam. _fam._ neritacea, lam.--_descr._ thin, semiglobose, obliquely oval, smooth, flattish in front; spire short, sometimes depressed, consisting of few rapidly increasing whorls; aperture semicircular; outer lip thin, sharp; columellar lip broad, flat, its inner edge straight, denticulated; operculum testaceous, semicircular, sub-spiral, with an articulating process on the inner edge.--_obs._ this genus of fresh-water shells differs from nerita in the minuteness of the denticulation of the columella, as well as in the characters mentioned in our observations upon the latter genus. n. spinosa, (clithon, montf.) fig. . n. virginea, fig. . n. perversa, lam. (velates, montf.) fig. . all the species known up to the present time, with the exception of three, are represented in the author's conchological illustrations, parts , , , , to . the catalogue accompanying these representations enumerates species. neritopsis. gray. _fam._ neritacea, lam.--_descr._ sub-globose, thick, cancellated; spire short, composed of few rapidly increasing whorls; aperture transverse, sub-orbicular; outer lip thickened within; columellar lip thick, rather flat, with a large rounded notch in the centre of its inner edge.--_obs._ this genus most nearly resembles nerita, from which it differs in the peculiar notch of the columella. n. granosa, fig. . nicania. leach. astarte, sowerby. the same as crassina of lamarck. nitidella. sw. a genus of "columbellinæ," sw. thus described: "bucciniform, small, ovate, smooth, glassy; aperture effuse; outer lip slightly thickened, faintly inflexed, and generally striated internally; inner lip somewhat flattened above; base of the pillar with one or two slight internal folds, or a single angular projection. columbella nitida, _lam._ (fig. , _c._ p. .)" sw. p. . nobia. leach. _order_, sessile cirripedes, lam. this genus resembles pyrgoma, auct. consisting of a conical paries, supported upon a funnel-shaped cavity in the madrepore, but differs in its operculum, which consists of two valves, whereas that of pyrgoma has four. n. grandis, fig. . nodosaria. lam. and orthocera have been united by sowerby under the name of the first. _fam._ orthocerata, lam. and bl.--_descr._ straight, chambered, elongated; chambers more or less ventricose; septa perforated by a central siphon.--_obs._ this genus consists only of fossils found in sub-appenine tertiary beds. it is placed by de blainville in one of his divisions of the genus orthoceras, which is characterized as "species not striated, and with chambers very much inflated." n. æqualis, fig. . nodose. having tubercles or knobs. nogrobs. montf. a fossil appearing from the figure and description to resemble belemnites. nonion. montf. a genus of microscopic foraminifera. nonionina. d'orb. a genus of microscopic foraminifera. notrema. rafinesque. a shell described as composed of three integral valves, concerning which de blainville puts the query, "ne seroit-ce pas plutôt une balanide mal observée?" novaculina. benson. (_novacula_, a razor.) _fam._ solenacea, lam.--_descr._ equivalve, inequilateral, transversely elongated; external ligament communicating with the interior of the shell by an oblique channel; beaks prominent; hinge line nearly straight, with one narrow curved cardinal tooth in one valve, entering between two similar teeth in the other; siphonal scar long; extremities of the shell gaping; epidermis thin, light brown, folding over the edges and connecting the dorsal margins. _hab._ jumna, gooti, and ganges. fig. . nucleobranchiata. bl. the fifth order of the second section of paracephalophora monoica, bl. the shells of which are described as symmetrical, more or less curved, or longitudinally rolled up and very thin. this order contains, _fam._ . nectopoda, containing carinaria; _fam._ . pteropoda, containing atlanta, spiratella and argonauta. nucleus. (_a kernel._) anything forming a centre around which matter is gathered. the nucleus of shells is the first formed part; the first deposit of shelly matter to which the successive layers are added; the apex of the spiral cone, of which most shells are composed. (see cone.) the nucleus is formed within the egg in oviparous, and within the old shell in viviparous mollusca. it is frequently more transparent and light than the remainder of the shell, and sometimes falls off; when this occurs the shell is said to be decollated. nucula. lam. (_a small nut._) _fam._ arcacea, bl. and lam.--_descr._ equivalve, inequilateral, transverse, covered with an epidermis; hinge linear, with a series of sharp, angulated teeth, arranged in a line on each side of the umbones, and a central ligamentary pit; muscular impressions two, simple; palleal impressions not sinuated.--_obs._ the row of teeth on each side of the umbones, and the ligamentary pit in the centre of the hinge prevent the pretty little shells of this genus from being confounded with any other. thirty-four figures are enumerated in the catalogue by sowerby, sen. which accompanies the conchological illustrations of the author. the new species, to the amount of , have been figured in parts to , of the above mentioned work. recent nuculæ are found from the frozen to the torrid zones, and the fossil species occur in nearly all the beds from the pliocene to the carboniferous system. nummulacea. bl. the third family of cellulacea, bl. described as containing shells or calcareous bodies, which are characterized as discoidal, lenticular; without the slightest traces of whorls to be seen externally. the whorls are numerous, internal, and divided into a great number of cells, which are separated from each other by imperforate septa. this family contains the genera nummulites, siderolites, vorticialis, helicites, orbiculina, placentula. nummulttes. lam. (_nummus_, money.) _fam._ nautilacea, lam.--_descr._ orbicular, convolute, shewing no trace of spire externally; interior divided into cells spirally arranged.--_obs._ the singular fossils composing this genus receive their name from their external resemblance to a battered coin. fig. . n. lenticulina. nux. humph. cyclas, lam. nymphacea. lam. a family belonging to the order conchifera dimyaria, lam. ligament external, placed on a prominent fulcrum. this family contains the following genera: . sanguinolaria. rostrated, gaping; two cardinal teeth in each valve, including _soletellina_ and _lobaria_. fig. , . . psammobia. quadrate; valves closed, including psammotæa. fig. . . corbis. thick, fimbriated; a cardinal tooth in the centre of a pit. fig. . . grateloupia. a series of small teeth filling a triangular area. fig. . . egeria. one single and one double cardinal tooth. fig. . . lucina. rounded; anterior muscular impression tongue-shaped. fig. . . tellina. an anterior fold in the ventral margin; lateral teeth. fig. , . . tellinides. no anterior fold; no lateral teeth. fig. . . donax. margin denticulated; shell wedge-shaped. fig. . . capsa. margin not denticulated, no lateral teeth. fig. . obeliscus. humph. trochus, lam. oblique. (_obliquus._ lat.) in a slanting direction. the whorls of spiral univalves generally take an oblique direction in reference to the imaginary axis of the shell. a bivalve is said to be oblique when it slants off from the umbones. an example of this is seen in avicula, fig. . obsolete. (_obsoletus_, lat.) worn out, out of use. this term is used to express an indistinctness of character, which sometimes results from the action of sea-water upon unprotected parts of the shell, and sometimes from the deposits of enamel formed in age, and covering the early striæ, ribs, teeth, &c. thereby rendering them less acute. obtuse. (_obtusus_, blunt.) the application of this term is not peculiar to conchology. it is most frequently used to express the character of the spire. _ex_. the apex of megaspira, fig. . oceanus. montf. ("corne d'ammon vivant," fr.) nautilus umbilicatus, auct. octhosia. ranz. clitia, leach. octocera. bl. the first family of the order cryptodibranchiata, bl. containing the genus octopus. a species of which being found in the argonauta, or paper sailor, has given rise to the long continued controversy as to whether it is really the constructor of the shell, or whether it is a mere pirate, and having destroyed the true animal of the argonaut, has possessed itself of the habitation. this question is now set at rest. see argonauta. octogonal. (_octogonum._) having eight angles. for an example, see dentalium, fig. . octomeris. sow. ([greek: oktô], _octo_, eight; [greek: meros], _meros_, part.) _fam._ balanidea, bl. _order_, sessile cirripedes, lam.--_descr._ eight principal valves circularly arranged, forming a compressed cone, attached by a jagged base; aperture enclosed by an operculum, consisting of four valves in pairs.--_obs._ the only genus of sessile cirripedes agreeing with this in the number of principal valves is catophragmus, sow. which is, however, sufficiently distinguished by the several rows of smaller valves by which the principals are surrounded at the base. o. angulosus, fig. . odontis. sow. monodonta, lam. odostomia. flem. _descr._ "shell conical; aperture ovate; peristome incomplete, retrally, and furnished with a tooth on the pillar." a genus composed of several small species of land shells. turbo plicatus, spiralis, unidentatus, &c. mont. oliva. auct. (_an olive._) _fam._ convoluta, lam. angyostomata. bl.--_descr._ oblong, cylindrical, thick, smooth, shining; spire very short, with sutures distinct, aperture elongated, notched at both extremities; outer lip generally thick; columella thick, obliquely striated, terminated by a tumid, oblique, striated varix; a raised band passing round the lower part of the body whorl.--_obs._ the shells composing this well known genus present a great variety of rich markings and brilliant colours. they are marine and tropical. fossil species are found sparingly in the london clay and calcaire-grossièr. the ancillariæ are distinguished from this genus by the sutures of the whorls being covered by enamel. o. maura, fig. . olivella. sw. a genus of "olivinæ," sw. thus described: "oliviform; spire (typically) rather produced; the tip acute; inner lip not thickened; outer lip straight; base of the pillar curved inwards, and marked by two strong plaits; upper plaits obsolete or wanting; aperture effused at the base only; biplicata, tank. cat. . purpurata. zool. ill. ii. . f. . mutabilis. _say._ eburnea. zool. ill. ii. , f. . conoidalis. _lam._ no. . oryza. _lam._ no. ." olygyra. say. mentioned by ranz as properly belonging to helicina. h. neritella, auct. omalaxis. desh. subsequently bifrontia. desh. fig. . oniscia. sow. (g. b.) _fam._ purpurifera, lam. entomostomata, bl.--_descr._ oblong, sub-ovate, slightly turbinated, cancellated; spire short; aperture elongated; terminating anteriorly in a very short, recurved canal; outer lip thickened, denticulated within; inner lip spread over a portion of the body whorl, granulated.--_obs._ the granulated inner lip is the principal character by which this genus is distinguished from cassidaria. in oniscia the canal is not so produced. o. oniscus, fig. . onustus. humph. a genus proposed by humphrey and adopted by swainson who describes it thus: "shell trochiform; the surface irregular, and often covered with extraneous bodies, cemented and incorporated with the calcareous substance of the shell; the under part of the body whorl flattened or concave, umbilicate. o. solaris. mart. . f. , . indicus. ib. . f. . ." it is probable, from the above description, that mr. swainson intended to include trochus agglutinans of authors. (genus phorus, montf.) fig. . opercular. of, or belonging to, the operculum. a term applied to the valves which compose the operculum of multivalve shells, as distinguished from the parietal valves, or those which are arranged circularly and form the body of the shell. operculina. d'orb. a genus of microscopic foraminifera. operculum. (_a cover or lid._) the plate or plates with which many molluscous animals enclose the aperture of their shells, when retired within them. the operculum is sometimes horny, as in trochus; testaceous or shelly, as in turbo. it is spiral when from a central or sub-central nucleus, the successive layers take a revolving direction, as in trochus. it is concentric or annular when the outside edge of each layer entirely surrounds the preceding one. it is unguiculated, when the laminæ are placed side by side, as in purpura. the opercula of multivalve shells are composed of two or four pieces, which are called the opercular valves. the shelly or membranaceous plate with which some of the animals enclose the aperture of their shells, during the wintry part of the year, for the purpose of protecting them while in a torpid state, and which they get rid of by dissolving the edges, when preparing to emerge from their temporary retirement, must not be considered as the operculum, as it does not belong to or form part of either the animal or its shell, but is produced for the occasion by a secretion of the animal, being deposited in a soft state and subsequently hardening. it is called the epiphragm, and may easily be distinguished from the true operculum by the texture, and by the circumstance of their being soldered to the edge of the aperture. the operculum, on the contrary, is moveable, and is always composed of a series of successive layers, corresponding with the growth of the shell. opis. defr. a genus described by de blainville as consisting of species of trigonia which have the umbones sub-spiral, with a large, striated tooth on the hinge. opis cardissoides, trigonia, lam. opis similis, sow. min. con. pl. . f. . oral. (_os_, _oris_, mouth.) applied to that part of a shell which corresponds with the mouth of the animal, but very seldom used in this sense. orbicula. lam. (_orbis_, an orb.) _fam._ brachiopoda, lam. palliobranchiata, bl.--_descr._ inequivalve, irregular, sub-orbicular, compressed, attached by a fibrous substance passing through a fissure near the centre of the lower valve; upper valve patelliform, with the umbo central; muscular impressions four in each valve, semilunar. south america and west indies.--_obs._ discina, lam. is an orbicula. crania is known from this genus by having no fissure in the lower valve, but being attached by its substance. hipponyx has only two muscular impressions in each valve. o. lævis, fig. . orbicular. (_orbiculus_, a little orb.) of a round or circular form. orbiculina. lam. a genus of microscopic foraminifera. orbis. lea. a minute fossil, described as "orbicular, with flat quadrate whorls and aperture square," in other respects resembling solarium. o. rotella, fig. , . orbitina. risso. a genus said to be established upon the nuclei of two land shells. orbulites. lam. a genus separated from ammonites on account of the last volution covering the spire. this is generally considered as characterizing the nautili, and distinguishing them from the ammonites; but there are so many gradations that it seems impossible to maintain the distinction in this respect. fig. , o. crassus, fig. , o. discus. oreas. montf. part of cristellaria, lam. a genus of microscopic foraminifera. orthis. dalman. ([greek: orthos], _orthos_, straight.) _fam._ brachiopoda, lam. one of the generic divisions of brachiopoda by dalman, thus described: "hinge rectilinear, with umbones distant; the larger valve with a transverse, basal, smooth area, with a triangular pit." o. basalis, fig. . orthocera. lam. see nodosaria. orthocerata. lam. a family of polythalamous cephalopoda, lam. containing the following genera:-- . conularia. conical, externally striated; no siphon. fig. . . amplexus. cylindrical; margins of the septa reflected. fig. . . orthoceratites. straight, gradually conical; septa simple; siphon central. fig. . . nodosaria. divided externally into lobes. fig. . . belemnites. straight, conical; septa simple; siphon lateral; apex solid; internal cast, or nucleus, pyramidal, separable. fig. to . . conilites. like belemnites, but external shell thin at the apex. fig. . orthocerata. bl. the first family of polythalamacea, bl. containing the genera belemnites, conularia, conilites, orthoceras and baculites. de blainville remarks that the genera included in this family are all fossils, and known very imperfectly, in consequence of the greater part of the specimens being only casts. orthoceratites. auct. _fam._ orthocerata, lam. and bl.--_descr._ straight, conical, divided into numerous chambers by simple septa perforated by a central siphon. o. annulata, fig. . osteodesma. desh. periploma, schum. ostracea. (_ostracées_, lam.) a family belonging to the second section of the order conchifera monomyaria, the shells of which are described as irregular, foliaceous, sometimes papyraceous, with the ligament wholly or partly interior. the principal difference between the ostracea and the pectinides consists in the absence of the auricles and the foliated structure of the shells, for, although the spondylus has ex-foliations or spines upon the external surface, the shell itself is compact and firm. this family contains the genera gryphæa, ostrea, vulsella, placuna, anomia, which may be thus distinguished:-- . pedum. flat, turned up at the sides, an hiatus for the passage of a byssus. a triangular disc on the hinge. fig. . . ostrea. foliaceous, irregular, hinge on a small triangular disc. including dendostrea, ostræa, exogyra, gryphæa. fig. to . . placuna. two diverging ribs near the umbones. fig. . . placunanomia. the same, but attached by fibres passing through a hole in one valve. fig. to . . anomia. no costæ, attached by a bony substance passing through a hole in one valve. fig. to . . vulsella. tongue-shaped, a ligamentary pit on the hinge. fig. . . mulleria. doubtful. fig. . ostracea. bl. the first family of the order lamellibranchiata, bl. containing the genera anomia, placuna, harpax, ostrea (including dendostrea, sw.) gryphæa. to these may be added placunanomia, brod. and mulleria. ostrea. auct. ([greek: ostreon], _ostreon_, a bone.) _fam._ ostracea, lam. and bl.--_descr._ irregular, inequivalve, generally inequilateral, foliaceous, attached by part of the lower valve; hinge sometimes slightly crenated; destitute of teeth; with the ligament spread upon the lower part of a central, triangular area, which is divided into three parts; upper valve much flatter than the lower; muscular impressions one in each valve, large, sub-central, sub-orbicular, with one very minute.--_obs._ the linnæan genus ostrea includes the pectens and many other genera so different from each other that, without any desire to increase the number of genera, it was found necessary by subsequent authors to separate them. the common oyster is the type of this genus as at present constituted, and is well known to be abundant in various parts of the world. those which depart furthest from this type are the gryphæa, lam. with a prominent, incurved umbo in the lower valve. the dendostrea, sw. with margins characterized by strongly angulated folds, throws out arms from the lower valve, by which they are attached to stems of sea-weed, &c. fig. , o. edulis. fig. , o. folium. (dendostrea, sw.) fig. , gryphæa incurva. fig. , exogyra conica. otides. bl. the first order of scutibranchiata, bl. containing the genera haliotis and ancylus. otion. leach. ([greek: ôtion], a little ear.) _order._ pedunculated cirripedes, lam.--_descr._ body sub-quadrate, supported on a fleshy pedicle with a gaping aperture and two posterior auricular tubes; valves five, separate, two semilunar, placed at the sides of the aperture, two terminal, very small, one dorsal, minute.--_obs._ otion differs from cineras in having two cylindrical posterior tubes, and in the extreme minuteness of three out of five of the valves. found on spars floating in the sea, &c. o. cuvierii, (lepas aurita, linn.) fig. , o. cuvieri. otis. humph. auricula, lam. ovate. (_ovatus._) egg-shaped or oval. oveolithes. montf. a microscopic shell resembling bulla. oviparous mollusca. those which produce their young in eggs. used in distinction from the viviparous mollusca, whose young are perfectly formed before they leave the body of the parent. outer lip. see labrum. ovulum. brug. (_ovum_, an egg, dim.) _fam._ convoluta, lam. angyostomata, bl.--_descr._ ovate or fusiform, smooth, convolute, spire covered; aperture narrow, with a canal at each extremity; outer lip crenulated, inflected; inner lip smooth, callous towards the spiral extremity; dorsal area wide, sometimes indistinctly marked.--_obs._ the ovula were placed by linnæus in his genus bulla, from which they are very remote. they differ from cypræa in having the inner lip smooth. we have given representations of their different forms as follows: o. ovum, fig. . o. verrucosum, (calpurnus montf.) fig. . o. volva, the weaver's shuttle (radius, montf.) fig. . o. gibbosum, (ultimus, montf.) fig. . oxystomata. bl. the fifth family of asiphonibranchiata, bl. this family appears to have been formed for the express purpose of providing a place in the system for the genus janthina, which seems to bear so little analogy with other genera of mollusca, that conchological writers have been puzzled to know where to place it. pachylabra. sw. pachystoma, guild. a sub-genus of ampullaria, the outer lip of which is thickened within. _ex._ ampullaria globosa. pachymya. sow. ([greek: pachus], _pachus_, thick, and _mya_.) _fam._ cardiacea? lam.--_descr._ obliquely elongated, equivalve, thick, sub-bilobed, with beaks near the anterior extremity; ligament partly immersed attached to prominent fulcra.--_obs._ this singular fossil is shaped like modiola, but the shell being extremely thick, and the ligament attached to a prominent fulcrum, it is difficult to know where to place it. fig. , pachymya gigas. pachystoma. guild. ([greek: pachus], _pachus_, thick; [greek: stoma], _stoma_, mouth.) a genus composed of such species of ampullaria, auct. as have the edge of the aperture thickened and grooved within so as to form a sort of ledge upon which the operculum rests. ampullaria globosa and corrugata are examples of this variation. the name pachylabra is given to such species by swainson, who objects to the above name on account of its having been previously used to a genus of fishes. fig. . pachytoma. sw. a sub-genus of helicina, thus described, "aperture entire; the inner lip very thick; the spiral whorls hardly convex; p. occidentalis. zool. j. iii. . f. - . viridis, zool. journ. i. pl. . f. ." sw. p. . paclites. montf. a genus composed of species of belemnites, auct. described towards the extremity, with a pore, at the apex, and a straight lengthened aperture. _ex._ b. ungulatus, bl. padollus. montf. a genus composed of species of haliotis, with a strongly marked spiral groove. _ex._ h. tricostalis, lam. fig. . pagodella. sw. a sub-genus of trochus, thus described: "trochiform; generally thin, and always not pearlaceous; aperture and pillar perfectly united and entire; operculum horny. p. major. mart. . f. , . tectum-persicum. ib. f. , ." sw. p. . palleal impression. (_pallium_, a mantle.) the mark or groove formed in a bivalve shell by the muscular attachment of the mantle, which, being always found near the margin of the shell, is sometimes termed the marginal impression. in bivalves with two muscular impressions it passes from one to the other. if in passing, it takes a bend inwards posteriorly, it is said to be sinuated, and that part is called by mr. gray, the siphonal scar. palliobranchiata. bl. the first order of the class acephalophora. bl. the animals of this order are described as more or less compressed, included between the two valves of a bivalve shell, one inferior, the other superior, joining at the back and opening in front. the palliobranchiata in the system of de blainville correspond with the brachiopoda in the system of lamarck, and the shells may be known by their being symmetrical. this order contains in the first section of symmetrical bivalves, lingula, terebratula, thecidium, strophomena, plagiostoma, dianchora and podopsis: in the second section, orbicula and crania. palmated. flattened like a palm, as the fronds or fringes of some murices. palmina. gray. differing from otion in having but one auricle. paludina. lam. _fam._ peristomata, lam. cricostomata, bl--_descr._ varying in form from oval to globose, in some instances oblong, covered with a greenish horny epidermis; spire acute, composed of rounded whorls; aperture ovate; peritreme entire, slightly modified by the last whorl; operculum horny, concentric. europe, north america, east indies, china, &c.--_obs._ the construction of the operculum distinguishes this genus of freshwater shells from valvata and cyclostoma. the paludinæ are viviparous. fig. . p. achatina. paludomus. sw. a genus of the family of "melanianæ," sw. described as differing from melania in having the spire shorter than the aperture. sw. p. . pandora. brug. _fam._ corbulacea, lam. pyloridea, bl.--_descr._ thin, inequivalve, pearly within, rounded anteriorly, rostrated posteriorly; right valve flat with a cardinal tooth, or short rib, and a slit containing the cartilage with a narrow plate on the dorsal edge turned towards the left valve; left valve concave, with a receptacle for the cardinal tooth of the right valve and the internal cartilage; no external ligament. europe, america, ceylon, &c.--_obs._ this well known genus is in no danger of being confounded with any other shell. fig. . p. rostrata. panopÆa. menard. _fam._ solenacea, lam. pyloridea, bl.--_descr._ equivalve, inequilateral, oval, gaping at both extremities; hinge with an acute cardinal tooth in each valve, and a large callosity near the umbones supporting the ligament; muscular impressions two, distant, oval; palleal impression with a large sinus. britain, north america, mediterranean, australia, &c.--_obs._ this genus resembles mya in general appearance, but differs in having an external ligament and a sharp tooth, instead of the broad spoon-shaped process in the hinge of the latter genus. fig. . p. australis. paper sailor. a common name given to the argonauta. papillary. (_papilla_, a teat.) shaped like a teat. this term is applied by conchologists when the apex of the spire of an univalve shell is rounded like a teat and not spiral up to the extreme point; as the apex of cymba, fig. . papyraceous. (_papyrus_, a kind of paper made of the flags of the river nile in egypt.) of a thin, light texture, resembling that of paper. an example of this is to be seen in the argonauta, commonly called the "paper sailor," fig. , and in the pholas papyracea, fig. . papyridea. sw. a sub-genus of cardium, thus described; "shell heart-shaped, or transversely oval; inequilateral; the anterior side almost always gaping; representing the pholidæ. p. soleniforme, wood, conch. pl. . f. .--apertum, ib. . f. .--transversum, sow. conch. f. .--ringens, wood, pl. . f. , ." paracephalophora. bl. the second class of the type malacozoa, bl. divided into the sub-classes: p. dioica, p. monoica, p. hermaphrodita. paries. (_a wall._) the principal part of a multivalve shell, forming a circular wall round the body of the animal, and composed of one or more valves which are called the parietal valves. parietal valves. the principal valves of multivalve shells surrounding the body like a wall; as distinguished from the opercular valves, or those which compose the operculum. parmacella. cuv. (_a little cell._) _fam._ limacinea, lam. and bl.--_descr._ haliotoid, internal, thin; spire flat, consisting of one or two rapidly increasing whorls; aperture as large as the whole shell, with the dorsal margins inflected.--_obs._ this description applies to parmacella of cuvier. the shell figured in sowerby's genera under that name is cryptella of webb. fig. , p. olivieri. fig. , p. palliolum. parmophorus. bl. a genus composed of emarginula elongata, auct. and other species of a similarly elongated form. australian. fig. . p. elongatus. partula. fer. _fam._ colimacea, lam. auriculacea, fer.--_descr._ conical, smooth; spire equal to the aperture in length, consisting of few whorls; aperture auriform; outer lip reflected, broad; inner lip reflected, with a slight prominence on the columella. p. australis, fig. . pasithÆa. lea. a genus formed of some pyramidal shells, described as resembling melania, but separated from that genus on account of being marine fossils. fig. , p. striata. patella. auct. (_a dish_ or _platter_.) _fam._ phyllidiana, lam. retifera, bl.--_descr._ symmetrical, compresso-conical, nearly regular, oblong or oval; apex sub-central, inclining towards the anterior margin; aperture oval, forming the base of the shell; internal surface smooth; with a muscular impression shaped like a horse-shoe, with the ends bending forwards, encircling and dividing the space all round, except where the interruption occurs to receive the head of the animal; external surface ribbed, grooved, striated or banded radiately. on rocks and sea-weeds in all climates.--_obs._ patelloida differs from patella in the construction of the animal; siphonaria, in the lateral siphon; and ancylus, in the oblique twist of the axis, as well as in the nature of the animal. the patellæ are marine. fig. , p. oculus. patelliform. (_patella_, a dish; _forma_, shape.) shaped like a dish, or like shells of the genus patella. patelloida. quoy and gaimard. lottia, gray.--_fam._ phyllidiana, lam.--_descr._ patelliform, rather flat; apex obtuse, leaning towards the posterior margin; muscular impression not symmetrical, but widest on the right side near the head of the animal; central disc of a variable brown colour. on rocks and sea-weeds in all climates.--_obs._ the shells of this genus so closely resemble patella that it is almost impossible to make the distinction from the shells alone. they are, however, generally flatter, and have the apex placed somewhat nearer the posterior margin. the animals are very distinct. fig. , p. antillarum. patelloidea, bl. or patelliform shells. the third family of the order monopleurobranchiata, bl.; the animals of which are described as depressed, flattened, covered by a wide external shell, which is patelliform and non-symmetrical. this family contains the genera umbrella and siphonaria. patrocles. montf. a genus of microscopic foraminifera. patularia. sw. a sub-genus of "anodontinæ," sw. thus described: "shell nearly equilateral, round or cordate; no teeth. p. ovata, sw." _ex._ _conch._ pl. . rotundatus, ib. pl. . pavonia. d'orb. a genus of microscopic foraminifera. paxyodon. schum. hyria, lam. pecten. brug. (_a comb._) _fam._ pectenides, lam. subostracea, bl.--_descr._ inequivalve, ribbed longitudinally, nearly equilateral, with a triangular auricle on each side of the umbones; hinge linear, destitute of teeth, having a central pit containing the cartilage; muscular impressions one in each valve, large, sub-central.--_obs._ this genus of beautiful shells, to which the well known scallop belongs, contains numerous species, some of which are found in the british seas. the hinnites pusio (p. pusio of some authors) has been separated on account of the irregularity of the external surface of one valve. fig. to . pectenides. lam. a family belonging to the second section of the order conchifera dimyaria, lam. including the following genera. . pecten. unattached, including _decatopecten_ and _hinnites_. fig. , , . . lima. unattached, gaping, fig. . . plagiostoma. unattached, with an area between the umbones. fig. . . dianchora. attached by the point of the umbo. fig. . . spondylus. attached, irregular, a triangular area in one valve, divided by a slit. fig. . . plicatula. plicated, a very small area in one valve. fig. . pectinated. (_pecten_, a comb.) marked in a regular series of ridges. pectunculus. (_pecten_, dim.) _fam._ arcacea, lam. and bl.--_descr._ equivalve, sub-equilateral, orbicular, thick, covered with a velvety epidermis, striated longitudinally; ventral margin denticulated within; hinge semi-circular, with a series of small teeth on each side of the umbones, which are separated by a small triangular disc in each valve bearing the ligament; muscular impressions two in each valve, strongly marked, united by an entire palleal impression.--_obs._ linnæan conchologists have mixed this genus with arca, from which it is, however, totally distinct, not only in the roundness of the general form, but also, and principally, in the curve of the hinge line; in fact the characters of this genus are so strongly marked that there is no danger of confounding it with any other. it does not contain many species; two or three are british. the fossil species occur in london clay and calcaire-grossiér. fig. , p. pilosus. pedicle or peduncle. (_pedunculus_, a little foot.) the stem or organ of attachment of the class of shells called in the system of lamarck "pedunculated cirripedes," consisting of a fleshy tendinous tube, by the lower end of which they are attached to sub-marine substances. pedicularia. sw. a genus of "scutibranchia," thus described: "shell irregular, sub-patelliform; a thick, large, obsolete apex on one of the longest sides, and an internal callous rim within, on one side only; circumference undulated, irregular. p. sicula, sw." sw. p. . sicily. a singular shell of the nature of calyptræa, which is found attached to corals, conforming its shape to the irregularity of their surface, and fitting closely. _ex._ fig. . pedipes. adanson. _fam._ auriculacea, bl. colimacea, lam.--_descr._ sub-globose, longitudinal, thick, striated; spire equal to the aperture in length; aperture sub-ovate; peritreme sharp, thickened within, modified by the last whorl; columella with three strong plaits on the inner edge; outer lip with one fold.--_obs._ this genus contains but one or two small recent species, which in some respects resemble auricula, from which it is known by the thickness of its shell, and its globular form. fig. , p. adansoni. coast of africa. pedum. lam. (_a shepherd's crook._) _fam._ pectinides, lam. sub-ostracea, bl.--_descr._ irregular, inequivalve, sub-equilateral, attached by a byssus passing through a sinus in the lower valve; hinge toothless, with a triangular area in each valve, separating the umbones; ligament contained in a groove running across the area; muscular impressions one in each valve, large, sub-orbicular; both valves flat, narrow at the dorsal, broad at the ventral extremities; lower valve with raised edges overwrapping the upper.--_obs._ this singular genus, of which only one species is known, differs from ostrea, not only in shape and structure, but also in the mode of attachment, which is by means of a byssus passing through the lower valve, in pedum, but by a portion of the outer surface of the shell in ostrea. p. spondyloideum (fig. ) is the only species at present known. moluccas. peduncle. see pedicle. pedunculated. (_pedunculus_, a little foot.) attached to external objects by a hollow fleshy tube, called the peduncle. pedunculated cirripedes. lam. an order consisting of molluscs which have multivalve shells, supported on a peduncle. the genera which it contains are thus distinguished: . pentelasmis. five valves. fig. . . cineras. five very minute valves distant from each other. fig. . . otion. the same, but the animal has two auricles. fig. . the genus palmina, gray, has but one. . octolasmis. shaped like pentelasmis, but with or valves. fig. . . lithotrya. five valves, peduncle scaly with a plate at the base. fig. . . scalpellum. shape square, valves , peduncle scaly. fig. . . smilium. same, but the peduncle hairy. fig. . . ibla. four valves, one pair long, one pair short, peduncle hairy. fig. . . brismeus. seven valves, even at the base. fig. . . pollicipes. principal valves in pairs, with many smaller valves at the base. this genus has been divided into _pollicipes_, and _capitellum_, the latter of which is founded upon pollicipes mitellus, auct. fig. and *. pelagus. montf. a genus composed of species of ammonites, which have the spire covered by the last whorl, as in nautilus and have an umbilicus. orbulites. bl. pellucid. transparent. pelorus. montf. polystomella, bl. a genus of microscopic foraminifera. peloronta. oken. nerita _peloronta_, auct. fig. . peneroplis. montf. a genus of microscopic foraminifera. penicillus. brug. aspergillum, auct. pentalepas. bl. pentelasmis, auct. pentamerus. sow. ([greek: pente], _pente_, five; [greek: meros], _meros_, part.) _fam._ brachiopoda, lam.--_descr._ equilateral, inequivalve; one valve divided by a central septum into two parts; the other by two septa, into three parts; umbones incurved, imperforate.--_obs._ dalman remarks upon his genus gypidia, that it is most probably identical with pentamerus, sow. but rejects the name for two reasons; st. that it has already been applied to a class of insects; nd. he disputes the fact of the shell being quinquelocular, i.e. not counting the triangular foramen in the hinge of the larger valve as one of the divisions. fig. , . pentelasmis. leach. ([greek: pente], _pente_, five; [greek: elasma], _elasma_, plate.) _order._ pedunculated cirripedes, lam.--_descr._ compressed, conical, composed of five valves; lower lateral pair sub-trigonal; upper lateral pair elongated, sub-quadrate; dorsal valve arcuate, peduncle elongated, smooth. found on floating wood in the sea.--_obs._ this genus is known from all others of the order by the number of valves. pentelasmis is the genus anatifera of lamarck. lepas anatifer, linn. fossil species of this marine genus are found in the calcaire-grossièr of paris, and in other similar beds. fig. , p. lævis. penultimate whorl. the last whorl but one. pera. leach. a genus composed of cyclas amnica, and other similar species. perdix. montf. dolium _perdix_, auct. perforated. (_perforatus._) bored through, as the apex of fissurella, fig. , and dentalium, fig. . perforation. (_perforo_, to bore, or pierce.) a round opening, having the appearance of being bored, as in haliotis, fig. . sometimes the term is applied to an umbilicus which penetrates a shell through the axis to the apex, as eulima splendidula, fig. . peribolus. brug. a genus founded upon young specimens of cyprÆa, with their outer lips not formed. periostracum. a name used by mr. gray to signify the substance which covers the outer surface of many shells, called the _epidermis_ by most conchological writers. "drap marin" is the name given to this substance by french naturalists. periploma. schum. _fam._ myariæ. a genus thus described: "shell very thin with the left valve more ventricose than the right; hinge toothless, ligament double, the external portion thin, the internal part thick, placed upon prominent, sometimes spoon-shaped hinge laminæ, and supported by a transverse bone; muscular impressions two, distant, palleal impression sinuated posteriorly." _ex._ p. inæquivalvis. fig. . _genus_, osteodesma, deshayes. peristomata. lam. a family belonging to the first section of the order trachelipoda, containing the following genera:-- . ampullaria. globose or discoidal; operculum concentric; including _pachystoma_, _lanistes_, _ceratodes_. fig. to . . paludina. oval; operculum concentric. fig. . . valvata. globose; operculum spiral. fig. . peristome. the edge of the aperture, including the inner and outer lips. peritreme. a term used to express the whole circumference of the aperture of a spiral shell. it is said to be notched or entire, simple, reflected, round or oval, &c. perlamater. schum. (_mother of pearl._) meleagrina margaritifera, lam. the pearl oyster. perna. auct. ("pernæ concharum generis," plin.) _fam._ malleacea, lam.--_descr._ sub-equivalve, irregular, compressed, foliaceous; hinge straight, linear, composed of a series of transverse, parallel grooves, containing the cartilage and intermediate spaces bearing the ligament; anterior margin with a sinus for the passage of a byssus; posterior ventral margin oblique, attenuated. _obs._ this genus is known from crenatula by the straightness, number and regularity of the grooves in the hinge and the sinus, for the passage of the byssus. fig. , p. ephippium. mostly tropical. persicula. schum. a genus formed of marginella _persicula_, auct. and other species having the spire concealed. fig. . persona. montf. (_mask_). a genus composed of triton _anus_, auct. and similar species. fig. . petricola. lam. (_petrus_, a stone; _cola_, an inhabitant.) _fam._ lithophagidæ, lam.--_descr._ equivalve, inequilateral, transversely ovate or oblong, rather irregular, anterior side rounded; posterior side more or less attenuated, slightly gaping; hinge with two cardinal teeth in each valve; muscular impressions two in each valve; palleal impression entire; ligament external.--_obs._ the petricolæ are found in holes made by the animals in rocks, madrepores, &c. they may be known from saxicava by the regularity of their form and the teeth on the hinge. fig. , . petrified fingers, candles, spectre candles, &c. are vulgar terms by which fossils of the genus belemnites were formerly known. phakellopleura. guild. a genus composed of those species of chiton, auct. which have bunches of hairs or hyaline bristles on each side of each valve on the margin. the chiton fascicularis, found on our own coasts, is a well known example. fig. . pharamus. montf. lenticulina, bl. a genus of microscopic foraminifera. pharetrium. könig. ([greek: pharetreôn], _pharetrion_, a quiver.)--_descr._ a testaceous body composed of two conical sheaths, one within the other, perforated at the apex, and joined together near the oral margin. p. fragile, fig. . in describing this genus, which appears to be the same as entalis of defrance, mr. könig expresses the supposition that it may probably belong to the class pteropoda. phasianella. auct. (_phasianus_, a pheasant.) _fam._ turbinacea, lam. ellipsostomata, bl.--_descr._ smooth, oval, variegated; aperture entire, oval; outer-lip thin; inner-lip thin, spread over a portion of the body whorl; columella smooth, rather thickened towards the base; operculum horny, spiral within; testaceous, incrassated without. britain, mediterranean, &c.; the fine large species are australian. some fossil species are found in the tertiary beds.--_obs._ the shells composing this genus are richly marked with lines and waves of various and delicate colours, and if the genus be restricted to those species which are smooth, and which have a thick shelly operculum, we may regard it as well defined; but there are some spirally-grooved species of turbo, linn. which, from their oval shape, have been considered as belonging to this genus. such species should not, in our opinion, be retained in this genus; they belong to littorina. p. variegata, fig. . phitia. gray. carychium, müller. pholadaria. lam. a family of the order conchifera dimyaria, lam. the animals contained in this family live in cavities bored by themselves in rocks, wood, &c. they are cylindrical in form. lamarck here places pholas and gastrochÆna, the last of which belongs more properly to the family of tubicolaria, where we have enumerated it. pholas has been divided into _pholas_, fig. , _martesia_, which has the valves nearly closed; and pholadidæa, fig. , which has the cup-shaped extension. the genus pholadomya, fig. , has been added, although of doubtful character. the genus galeomma, fig. , , has also been recently added. pholadidÆa. leach. pholas papyracea, auct. remarkable for the cup-shaped process at the posterior extremity. fig. . pholadomya. sow. (_pholas_ and _mya_.) _fam._ pholadaria, lam.--_descr._ thin, rather hyaline, equivalve, inequilateral, ventricose, posteriorly gaping, elongated, anteriorly short, rounding; ventral margin rather gaping; hinge with an elongated pit, and lateral plate in each valve; ligament external, short, muscular impressions two in each valve, rather indistinct; palleal impression with a large sinus.--_obs._ the only recent species of this genus is from the island of tortola. several fossil species occur in rocks of the oolitic series. fig. , p. candida. pholas. auct. ([greek: phôleô], _pholeo_, to lie hid in a cavity.) _fam._ pholadaria, lam. adesmacea, bl.--_descr._ transverse, oblong, equivalve, inequilateral, imbricated, gaping on both sides, the anterior hiatus being generally the largest, although sometimes nearly closed, with the dorsal margin surmounted with one or more laminar accessary valves; hinge callous, reflected, with a long curved tooth protruding from beneath the umbones in each valve.--_obs._ this genus of marine shells, dwelling in holes formed in rocks, wood, &c. is easily distinguished from any other nearly allied genus by the curved, prominent, rib-like teeth. fig. , p. dactylus; . p. papyracea. pholeobius. leach. part of the genus saxicava, auct. phonemus. montf. a genus of microscopic foraminifera. phorus. montf. trochus agglutinans, auct. remarkable for the adhesion of little pebbles, dead shells, &c. to the outer edge of the whorls, which are taken up in the course of the growth of the shell. from this circumstance they are called "collectors, carriers, &c." fig. . recent species are brought from the east and west indies; fossil species are found in the tertiary beds. phos. montf. _fam._ purpurifera? lam.--_descr._ turrited, thick, cancellated, varicose; spire pointed, generally longer than the aperture; aperture rounded or oval; outer lip having internal ridges, with a sinus near the anterior termination; columella with an oblique fold; canal short, forming externally a raised varix.--_obs._ the raised external surface of the canal, brings this genus near to buccinum, while, in general appearance, most of the species more nearly resemble murex. they have, however, no true varices on the whorls, but merely raised bars. fig. , p. senticosus. phyllidiana. lam. a family belonging to the first section of the order gasteropoda, lam. the genera belonging to this family may be distinguished as follows: . chiton. composed of eight valves; valves contingent. fig. . . chitonellus. the same, with the valves distant. fig. . . patella. conical, symmetrical. fig. , . . patelloida. differing from patella in the animal. fig. . . siphonaria. with a siphon on one side. fig. *. . scutella. siphon close to the side of the head. fig. , . phyllonotus. sw. a sub-genus of murex, thus described: "canal moderate; varices foliated, laciniated, compressed, or resembling leaves; inflatus. mart. . fig. , eurystoma. zool. ill. ii. . imperialis. ib. pl. ." sw. p. . physa. drap. a genus formed for reversed species of limnæa, auct. fig. , p. castanea. physeter. humph. solarium, lam. pileolus. cookson. (_a little cap._) _fam._ neritacea, lam.--_descr._ patelliform, with the apex sub-central, straight. in the lower disc, or under surface, the centre of which is rather raised or cushion-shaped, is placed the lateral, narrow, semilunar aperture, with the outer lip marginated and the inner lip crenulated.--_obs._ this interesting genus is known only in a fossil state. two species are found in the upper layer of oolite, above the bradford clay. the spire, although internal, connects this genus in some degree with neritina. still there is no danger of confounding them. fig. , p. plicatus. pileopsis. lam. capulus, montf. pillar. the usual english name for the column which forms the axis of spiral shells, around which the whorls revolve. see columella. pinna. auct. (_the fin of a fish._) _fam._ mytilacea, lam.--_descr._ equivalve, inequilateral, oblique, wedge-shaped, thin, horny; umbones terminal; hinge rectilinear, without teeth; anterior margin sinuated, to admit the passage of a byssus; posterior margin truncated, gaping; muscular impressions two in each valve; posterior large, sub-central; anterior small, terminal, sometimes double.--_obs._ the beautiful large shells of which this genus is composed, are possessed of a large, flowing, silky byssus, of which gloves and hose have been manufactured. they have received their name from their resemblance to the pectoral fins of some fishes. some species attain very large dimensions, and measure two feet in length. a very improbable story is told with regard to animals of this genus, namely that a certain small species of crab is in the habit of taking refuge from its enemies in the shell of the pinna, into which it is received with great hospitality and kindness by the "_blind slug_," which inhabits it. in return for which kindness, he occasionally goes abroad to procure food for both. on his return he knocks at the shell, which is opened to receive him, and they share the supplies together in convivial security! some species are smooth, although the greater number are imbricated or crisped outside. p. saccata, fig. . pinnated. (from _pinna_, a fin.) when a part of a shell is spread out and smooth, as in rostellaria columbaria, fig. , it is said to be _alated_, or winged, but when the part which is spread is radiated or ribbed, like the fin of a fish, it is _pinnated_, as in murex pinnatus, and murex tripterus. (conch. illustr.) pirena. lam. a genus of fresh-water shells, rejected by de ferussac and other authors, who place lamarck's two first species with melanopsis, and his two last with melania. fig. , p. terebralis. pisidium. leach. a genus of river shells separated from cyclas principally on account of a difference in the animal. the species of pisidium, however, are less equilateral than the cyclades, and the posterior or ligamentary side of the latter is the longer, while that of the former is the shorter. fig. . pisiform. (_pisum_, a pea; _forma_, shape.) shaped like a pea or small globular body. pisum. megerle. (_a pea._) pisidium, leach. pithohelix. sw. a sub-genus of "geotrochus," sw. sw. p. . pitonellus. montf. rotella, auct. placenta. schum. placuna, auct. placentula. schum. a genus of microscopic foraminifera. placuna. brug. ([greek: plakous], _placos_, a cake.) _fam._ ostracea, lam. and bl.--_descr._ compressed, thin, equivalve, nearly equilateral, planorbicular, fibrous, foliaceous; hinge flat, with two diverging ribs in one valve, and two corresponding grooves in the other, containing the cartilage; muscular impressions one, large, circular, central, and one or two smaller in each valve.--_obs._ the two best known species of this well defined genus are the p. placenta, commonly called the chinese window shell, and the p. sella, called the saddle oyster, from the anterior margin being turned up so as to resemble a saddle. the genus may be known from all others by the diverging costa on the hinge. placunanomia is the only genus resembling it in this respect, but this is easily distinguished by a perforation through the shell. fig. , p. placuna. these shells are used in china to glaze windows. placunanomia. (sw. _placuna_ and _anomia_.) _fam._ ostracea, lam. and bl.--_descr._ thin, foliaceous, compressed, sub-equivalve, sub-equilateral, irregular, flat near the umbones, plicated towards the margins, attached by a bony substance passing through a fissure in the lower valve; hinge flat, with two diverging ribs in one valve, corresponding with two diverging grooves, containing the cartilage, in the other; muscular impressions one in each valve, central, sub-orbicular.--_obs._ the specimens from which mr. broderip described this singular genus, were brought by mr. cuming from the gulf of dulce in costa rico. another species is from one of the philippine islands. they partake of the characters of several genera, having the hinge of placuna, and being attached by a process passing through the lower valve, like anomia. p. cumingii, fig. . plagiostoma. sow. min. con. ([greek: plagios], _plagios_, oblique; [greek: stoma], _stoma_, mouth.) _fam._ pectenides, lam. palliobranchiata, bl.--_descr._ sub-equivalve, inequilateral, oblique, auriculated on each side of the umbones, radiately striated; hinge straight in one valve, with a triangular notch in the other.--_obs._ this genus, one species of which is spinous, and another smooth, is only known in a fossil state. it is found in the lias and chalk. fig. , p. spinosum. plait or fold. a term applied to the prominences on the columellar lip of some univalve shells, particularly in the sub-family of volutidæ. _ex._ voluta, fig. ; cymba, ; and melo, fig. . planaria. brown. a minute fossil resembling planorbis in appearance, but differing in being a marine shell, and having a reflected outer lip. p. nitens, fig. , from lea's contributions to geology. planaxis. lam. (_plana_, flat; and _axis_.) _fam._ turbinacea, lam. entomostomata, bl.--_descr._ sub-ovate, pyramidal, solid; spire measuring ½ or / of the axis, consisting of few whorls; columella contiguous to the axis, flat, truncated, and separated from the outer lip by a short canal; outer lip thickened and denticulated within; operculum horny, thin, with a terminal nucleus.--_obs._ this is a genus of small marine shells found in the west indies, &c. fig. , p. sulcata. plane. (_planus._) flat, planed, as the columellar lip of purpura, fig. . planorbicular, (_planus_, flat; _orbis_, an orb.) flat and circular, as ammonites, fig. . planorbis. müll. (_planus_, flat; _orbis_, an orb.) _fam._ lymnacea, lam. and bl.--_descr._ thin, horny, convolute, planorbicular, nearly symmetrical; spire compressed, concave, consisting of numerous gradually increasing whorls, which are visible on both sides; aperture transversely oval, or nearly round; peritreme entire; outer lip thin; inner lip distinct, spread over a part of the body whorl.--_obs._ this is a genus of shells abounding in all climates in ditches and stagnant pools, not liable to be confounded with any other, excepting the discoidal species of ampullaria, which may be distinguished by the aperture being broadest in the opposite direction. it is further to be remarked that the discoidal ampullariæ are dextral shells, and the planorbes are sinistral or reversed; and although the latter are sometimes so flat and orbicular that it is difficult to know which is the spiral side, it may nevertheless always be ascertained by a careful examination. fossil species are found in the freshwater strata of the isle of wight, and the neighbourhood of paris. fig. , p. corneus. planorbulina. d'orb. a genus of microscopic foraminifera. planulacea. bl. the second family of cellulacea, bl. the microscopic foraminifera contained in this family are described as very much depressed, not spiral, chambered, cellular, and having the septa indicated by grooves on the external surface of the shell, which increase in length from the apex to the base: some of the small cellular cavities are to be seen on the margins. this family contains the genera renulina and peneroplis. planularia. defr. peneroplis, montf. a genus of microscopic foraminifera. planulina. d'orb. a genus of microscopic foraminifera. planulites. lam. discorbites of the same author. a genus of microscopic foraminifera. platiris. lea. ([greek: platus], _platus_, wide; [greek: iris], _iris_.) a genus including several species of nayades, referred to iridina, lam. the genus platiris is divided into two sub-genera. iridina, species which have crenulated margins; i. ovata, i. exotica, spatha, lea; those with smooth or very slightly crenulated hinges, s. rubeus, s. solenoides, mycetopus, d'orb. fig. . platylepas. ([greek: platus], _platus_, wide; [greek: lepas], _lepas_, rock.) _order._ sessile cirripedes, lam. _fam._ balanidea, bl.--_descr._ conical, depressed, consisting of six valves, each divided internally by an angular plate jutting from the centre (like the buttress of a wall); operculum consisting of four valves in pairs.--_obs._ this genus differs from balanus, coronula, &c. in the internal structure of the valves. de blainville's description of chthalamus partly agrees with this. fig. . plectophorus. fer. ([greek: plêktron], _plectron_, spur; [greek: phoreô], _phoreo_, to carry.) a genus consisting of small testaceous appendages fixed on the posterior extremity of a species of slug. p. corninus, fig. . pleiodon. conrad. iridina, lam. _fam._ nayades, lam. plekocheilus. guild. auricula caprella, lam. carychium undulatum, leach. (caprella, nonnull.) this proposed genus is described as scarcely umbilical, dextral, oval, spiral; with the spire elevated, obtuse; the two last whorls very large, ventricose; aperture entire, elongated; columella with a single plait; the plait concave, inflected. fig. , . pleurobranchus. cuv. ([greek: pleura], _pleura_, the side; _branchiæ_, gills.) _fam._ semiphyllidiana, lam. subaplysiacea, bl.--_descr._ internal, thin, haliotoid, slightly convex towards the spiral apex; aperture entire.--_obs._ this is a very light shell, delicately coloured, resembling aplysia, but differing in the integrity of the margin. fig. , p. membranaceus. pleurocerus. rafinesque. a genus very imperfectly described in the "journal de physique" as "oval, or pyramidal; aperture oblong; outer lip thin; inner lip truncated at the columella, which is smooth and tortuous, not umbilicated. operculum horny or membranaceous." de blainville, in giving this description, remarks that he has neither seen the animal nor the shell of this genus, which he imagines to have been formed from the "paludine coupée de m. say." pleurorynchus. phillips. ([greek: pleura], _pleura_, the side; [greek: runchos], _rynchus_, a beak.) a genus founded upon a very singular species of cardium, distinguished by the short anterior side, and the elongation of the hinge line into auricular processes, which are truncated at the extremities. c. hibernicum from the black rock near dublin, which is vulgarly called asses-hoof, and c. elongatum (sow. min. con. vol. i. .), form part of this genus. pleurotoma. lam. _fam._ canalifera, lam. siphonostomata, bl.--_descr._ fusiform, thick, in general ribbed or striated transversely; aperture oval, terminating anteriorly in an elongated canal; outer lip thin, with a fissure near its spiral extremity; columella smooth, nearly straight. found principally in tropical climates.--_obs._ this genus, which nearly resembles fusus in other respects, may be known by the notch in the outer lip. the species differ in the length of the canal. swainson has designated this genus a family, thus divided into genera: brachytoma, in the description of which he says that the spire and aperture are of equal length, including the species strombiformis: pleurotoma, in which the channel is so much lengthened, as to be little shorter than the spire: clavatula, having the long narrow slit of pleurotoma, but with a very short canal: clavicantha, having the canal equally short, but the sinus or notch, instead of being linear and long, is short and wide; the surface is rough, and the whorls either coronated with prickles, or with compressed nodules resembling spines: tomella, which has the spire and canal fusiform, but the spire of very few whorls, and the inner lip considerably thickened within where it joins the outer lip. fig. , , p. marmorata; , p. strombiformis, (clavatula, sw.) pleurotomaria. defr. _fam._ turbinacea, lam.--_descr._ turbinated, spiral; aperture sub-quadrate, with rounded angles; outer lip with a deep slit near its union with the spire.--_obs._ this genus, which is only known in a fossil state, abounds in inferior oolite, oxford clay, and casts are found in a limestone bed in norway. the scissurellæ differ in being very minute shells, and are not so trochiform as the species of pleurotomaria, p. reticulata, fig. . plicacea. lam. a family of the order trachelipoda, lam. containing the following genera: . pyramidella. pyramidal, with numerous whorls. fig. . . tornatella. cylindrical, with few whorls. fig. , . . ringicula. margin reflected. fig. , . plicadomus. sw. a sub-genus of pupa, thus described: "spire moderate, regular and thick, but gradually conic; the tip obtuse; aperture perpendicular; inner lip wanting; outer lip semicircular; the margin dilated and reflected. p. sulcata, chem. , f. , ." sw. p. . plicated. (_plicatus_, folded.) applied to spiral plaits on the columella of some shells. _ex._ voluta, fig. . also to the angular bendings in the margins of some bivalve shells. _ex._ dendostrea, fig. . plicatula. lam. (_plicatus_, folded.) _fam._ pectenides, lam. sub-ostracea, bl.--_descr._ irregular, sub-equivalve, sub-equilateral, attached by a small part of the surface of one valve, strongly plicated; umbones separated by a small, external ligamentary area; hinge with two cardinal teeth in each valve, two approximate in one valve, received between two distant in the other; cartilage placed between the cardinal teeth; muscular impressions one in each valve.--_obs._ the cardinal teeth resembling those of spondylus, distinguish this genus from others of the lamarckian family pectenides. very few species are yet known, they are brought from the east and west indies and the philippine islands. fossil species are found in several of the supra-cretaceous beds. fig. , p. gibbosa. pneumobranchia. lam. the second section of the order gasteropoda, lam. containing the family limacinea, fig. to . podopsis. lam. this genus appears to have been described from specimens of a species of spondylus, with the triangular disc broken out, so as to present a similarly shaped foramen, which was supposed to afford a passage for a large byssus. polinices. montf. a genus composed of natica mammilla, and other similar species, with mammillated spires, and the umbilicus filled with enamel. fig. . pollia. gray. tritonidea, sw. the name given by gray was pre-occupied by a genus of lepidopterous insects. pollicipes. leach. (_pollex_, a thumb's breadth; _pes_, a foot.) _order._ pedunculated cirripedes, lam.--_descr._ conical, compressed, consisting of numerous valves, mostly in pairs, three or four pairs forming the principal part of the shell, and surrounded at the base by two or three rows of smaller valves, supported on a scaly, short pedicle.--_obs._ this description will be found to exclude scalpellum, and smilium, the valves of which are more equal. the p. mitellus, auct. (fig. *), has been separated as a genus under the name of mitellus by some authors, and it is certainly very different from p. polymerus, fig. , and p. cornucopia. pollontes. montf. miliola, bl. a genus of microscopic foraminifera. polybranchiata. bl. ([greek: polus], _polus_, many; _branchiæ_, gills.) the fifth family of the order lamellibranchiata, bl. containing the genera arca, pectunculus and nucula, which have a series of small teeth on the hinge. polydontes. montf. ([greek: polus], _polus_, many; [greek: odos], _odos_, tooth.) a species of helix, shaped like carocolla, and having a number of teeth in the aperture. polygonal. many-sided. polygonum. schum. ([greek: polus], _polus_, many; [greek: gônia], _gonia_, an angle.) a genus composed of species of turbinella, auct. which have large continuous costæ, so as to present the appearance of many-sided shells. t. polygonus, fig. . this generic name may be used to include all those species of turbinella, auct. which have very small folds on the columella. polygyra. say. a genus of heliciform shells, characterized by the large number of close set whorls, constituting the spire. _ex._ p. septemvolvus, fig. , . polylepas. bl. ([greek: polus], _polus_, many; [greek: lepas], _lepas_, rock.) scalpellum, auct. polymorphina. d'orb. a genus of microscopic foraminifera. polyphemus. montf. a genus composed of species of achatina, auct. which have elongated apertures, short spires, and an undulation in the outer lip. p. glans, fig. . polyplaxiphora. bl. the second class of the sub-type malentozoa, bl. containing the genus chiton. polystomella. lam. a genus of microscopic foraminifera. polythalamacea. bl. ([greek: polus], _polus_, many; [greek: thalamos], _thalamos_, chambers.) the third order of cephalophora, bl. the shells of which are described as straight, more or less symmetrically convolute, divided into several chambers. the septa are sometimes, but not always, pierced by one or more siphons. this order is divided into the families, orthocerata, lituacea, cristacea, ammonacea, nautilacea, turbinacea, turriculacea, all of which contain genera of chambered shells. de blainville arranges these families according to the degree in which the spires revolve. the first being straight, as the orthocerata, and the last being so closely coiled up, that the last whorl covers the rest, as in the nautilacea. polythalamia. lam. the first division of the order cephalopoda, lam. containing the following families of chambered shells, viz. orthocerata, lituacea, cristacea, sphærulacea, radiolata, nautilacea, ammonacea. fig. to . polytropa. sw. a genus of "scolyminæ," sw. thus described: "bucciniform; but the base narrow, and ending in a straight and contracted, but rather short, channel; spire longer, or as long as the aperture; exterior folliculated, or tuberculated; inner lip flattened, as in _purpura_; basal notch small, oblique; no internal channel; crispata. en. méth. , f. . chem. , f. . capilla, pennant, pl. , f. , imbricata. mart. . f. . ? rugosa. chem. f. - ." sw. p. . polyxenes. montf. a genus of microscopic foraminifera. pomatia. gesner. (gray, syn. b. m. p. .) a genus of the family of "cyclostomidæ," described as having "an elongated shell with reflexed lips, and a horny spiral operculum." also a sub-genus of snails, containing helix pomatia, auct. (gray's turton, p. .) pornus. humph. ampullaria, lam. porcellana. adanson. marginella, auct. porodragus. montf. a genus composed of species of belemnites, placed by de blainville in the section characterized as swelled near the apex, and straightened towards the base. posidonia. brong. a genus formed on the cast of a bivalve shell, common on schists from dillemberg. posterior. (_after_, _behind_.) the posterior or hinder part of a bivalve shell, is that in which the siphonal tube of the animal is placed. it is known in the shell, by the direction of the curve in the umbones, which is from the posterior towards the anterior; also by the ligament, which is always placed on the posterior part of the hinge, when it exists only on one side of the umbones; and by the sinus (when there is one) in the palleal impression, which is always near the posterior muscular impression. in some shells, however, it is very difficult for a learner to trace these marks; such bivalves, for instance, as have the ligament spread out on both sides of the umbones; such as are nearly symmetrical, and have the umbones consequently straight, and a single muscular impression near the centre of the valve. the brachiopodous bivalves have a different position, with relation to the animal, from the other bivalves, so that the hinge line is the posterior extremity, and the part where the valves open, is the anterior. the posterior extremity of the aperture of a spiral univalve shell, is that nearest to the spire. in patelliform shells the anterior and posterior extremities are distinguished by the muscular impression, which is annular, enclosing a central disc in the inner surface of the shell, excepting where it is interrupted by the place where the head of the animal lies, which of course is anterior. the posterior is marked _p._ in fig. , and . see anterior. postero-basal margin of a bivalve shell is the posterior side of the margin opposite the hinge. postero-dorsal margin is the posterior side of the hinge. potamis or potamides. brong. a genus of fresh-water shells resembling cerithium in the characters of the aperture, but which may be known from that genus by the thick, horny epidermis with which they are coated. p. muricata, fig. . (cerithium, sow.) we think that these shells should be placed near melania. potamomya. a genus of shells resembling corbula, in every respect except that of being inhabitants of fresh-water. fig. , , represents one of these fresh-water corbulæ. potamophila. sow. ([greek: potamis], _potamis_, river; [greek: philios], _philios_, choice.) "conques fluviatiles," lam.--_descr._ thick, equivalve, inequilateral, trigonal, covered with a greenish brown, smooth, horny epidermis; hinge thickened, broad, with one central, notched cardinal tooth in one valve, and two in the other, with indistinct lateral teeth; ligament large, supported on prominent fulcra; muscular impressions two in each valve, sub-orbicular.--_obs._ the name given to this shell refers to its place of abode, being found in rivers. it is the venus sub-viridis of some authors, although being a fresh-water shell, and having an incrassated hinge, and a smooth, thick epidermis, it is most distinct from that genus. it is described by bowdich under the name megadesma, on account of its large ligament, and by lamarck under that of galathæa, a name previously used by him for a genus of crustacea. p. radiata, fig. . megadesma appears to be the preferable name, since it has the right of priority over potamophila. it is found in africa. priamus. a genus composed of achatina priamus, lam. buccinum stercus--pulicum, chemn. conch. . t. . f. - . this shell is ascertained to belong to a marine mollusc, having a horny operculum, and therefore is justly considered to form a distinct genus, allied to the buccina and struthiolariæ. fig. . prisodon. schum. hyria, &c. auct. fig. . produced. (_productus_, prominent.) a term applied to the spire of univalve shells, or to any other prominent portion. producta. sow. (_productus_, produced.) _fam._ brachiopoda, lam.--_descr._ equilateral, inequivalve, thick, striated; one valve generally convex, with the margin inflected, produced; the other valve flat, or slightly convex, with the margin reflected; hinge rectilinear, transverse.--_obs._ the peculiarity of this genus, from which it derives its name, is the manner in which the anterior margins of the valves are drawn out and overwrap each other. the genus is only known in a fossil state. species occur in mountain limestone, and transition limestone of older date. p. depressa, fig. . proserpina. gray? fig. , represents a small shell belonging to the helix tribe, to which it is believed, mr. gray has applied the name proserpina nitida. we do not know how the genus is defined. proto. defr. a fossil shell resembling turritella, but having a spiral band reaching to the centre of each valve. p. terebralis, bl. psammobia. lam. _fam._ nymphacea, lam.--_descr._ transverse, oblong, slightly gaping at both ends; hinge with two cardinal teeth in one valve, one in the other; ligament supported upon a prominent fulcrum; muscular impressions two in each valve, sub-orbicular, distant; palleal impression with a large sinus; epidermis thin.--_obs._ the genus thus described includes psammotÆa of lamarck, which, according to him, only differs in the number of teeth, and which he says are but "psammobies dégenerées." the difference appears to be accidental. this genus differs from tellina in not having a posterior fold in the margin. fig. . the species are found in temperate and tropical climates. psammocola. bl. ([greek: psammos], _psammos_, sand; _cola_, an inhabitant.) a name given by de blainville to shells of the genus psammobia, including psammotÆa of lamarck. psammotÆa. see lam. psammobia. pseudoliva. sw. a genus of "eburninæ," sw. thus described: "shell thick, oval, oliviform, ventricose; spire very short, acute; base with two parallel grooves, one of which forms a notch at the base of the outer lip; suture slightly channelled; inner lip very thick, and turning inwards; aperture with an internal canal. connects the turbinellidÆ with the volutidÆ. p. plumbea, chem. . f. , ." sw. p. . psilostomata. bl. the third family of aporobranchiata, bl. containing no genera of shells. pteroceras. auct. ([greek: pteron], _pteron_, a wing; [greek: keras], _ceras_, horn.) _fam._ ailées, lam.--_descr._ turrited, oval, ventricose, thick, tuberculated; spire short; aperture oval, terminating in a lengthened canal at both extremities; outer lip thickened, expanded, produced into horn-shaped, hollow, thickened spires, with an anterior sinus apart from the canal.--_obs._ this genus, containing the shells commonly called devil's claws, gouty scorpions, spiders, &c. is distinguished from strombus by the digitations of the outer lip. no fossil species are known. fig. , p. aurantiaca. pterocyclos. benson. syn. b. m. p. . a genus formed of species of cyclostoma, auct. which have "a groove or hole at the hinder part of the mouth." pteropoda. lam. ([greek: pteron], _pteron_, a wing; [greek: pous], _pous_, a foot.) the first order of the class mollusca, lam. consisting of molluscs whose organs of locomotion consist of a pair of wing-shaped fins. this order contains the genera hyalæa, clio, cleodora, spiratella, cymbulia, and pneumoderma. to which may be added other genera enumerated in explanation of figures to . they may be thus distinguished. . atlanta. shaped like nautilus, symmetrical. fig. . . spiratella. spiral, not symmetrical. fig. . . creseis. straight, thorn-shaped. fig. . . vaginula. straight, widened in the centre; apex pointed. fig. . . cuvieria. the same; apex blunt. fig. . . cleodora. aperture with three spines; apex recurved. fig. . . hyalÆa. vaulted, open extremity, three-cornered; apex tridentate. fig. . pteropoda. bl. the second family of nucleobranchiata, bl. the shells of which are described as symmetrical, extremely thin, transparent, longitudinally enrolled, either forwards or backwards. the animals are remarkable for a pair of broad, flat, natatory organs or membranaceous fins, from which the family derives its name. it contains, in the system of de blainville, the genera atlanta, spiratella, and argonauta, to which may probably be added pharetrium, könig; entalis, defrance. pullastra. sow. _fam._ conques marines, lam.--_descr._ equivalve, ovate or oblong, transverse, inequilateral; hinge with three diverging cardinal teeth in each valve, notched at the terminations; muscular impressions two in each valve; palleal impression having a large sinus; ligament external, partly hidden by the dorsal margin.--_obs._ this genus includes the venerirupes of lamarck, and several species of his veneres, they are found in the sand on the shores of temperate and tropical climates. fig. , p. textile. pulmonobranchiata. bl. the first order of the first section of paracephalophora monoica, containing the families limnacea, auriculacea, and limacinea. pulvinites. defr. (_pulvinus_, a cushion.) _fam._ malleacea, lam.--_descr._ sub-equivalve, inequilateral, compressed, thin, slightly gaping posteriorly; one valve flat, the other rather concave; hinge linear, short, divided into perpendicular grooves; muscular impressions two, one sub-central, the other above it, nearer the hinge.--_obs._ this fossil shell is imperfectly known, and it is difficult to give a sufficient reason for separating it from perna. it comes from the baculite limestone of normandy. fig. , p. adansonii. punctated. (_punctatus_, spotted or dotted.) for example, see conus nussatella. fig. . puncticulis. sw. a sub-genus of "coronaxis," sw. (conus) described in swainson's malacology, page . puncturella. lowe. cemoria, leach. pupa. auct. _fam._ colimacea, lam.; limacinea, bl.--_descr._ cylindrical, generally ribbed; spire long, obtuse, composed of numerous slowly increasing whorls; aperture sub-quadrate, rounded anteriorly, entire; outer lip thickened; columella plaited.--_obs._ this genus is composed of land shells very variable in form, differing from bulinus in the numerous slowly increasing whorls of the spire, and in the plicæ on the columella, and from clausilia in the want of a clausium. britain, southern europe, east and west indies, mexico, &c. p. uva. fig. . pupella. sw. a sub-genus of clausilia. lardn. cyclop. malac. p. . pupilla. leach. a sub-genus of pupa, p. marginata, auct. (gray's turton, p. .) pupina. vignard. moulinsia, grateloup. _fam._ colimacea, lam.--_descr._ pupiform, sub-cylindrical; last whorl less than the preceding; surface brilliantly polished; suture of the spire enamelled; aperture circular; peritreme thickened; a notch at the base of the inner lip; operculum horny, spiral.--_obs._ the species upon which this genus was originally founded, and described in the "annal des sciences naturelles," tome , p. , (december ,) is a small pupiform shell, having nothing to distinguish it but the enamelled suture and the notch in the aperture; characters quite insufficient in themselves for the purpose of generic distinction; at the same time sufficient to lead m. de ferussac to the suspicion of its having an operculum. the next species, described by grateloup under the name of moulinsia nunezii, (ann. soc. linn. burd, nov. ), presents more remarkable characters, having the spire turned backwards and the penultimate whorl disproportionately large. seven additional species have been lately brought to this country from the philippine islands by mr. cuming. they will be described by the author in the zoological proceedings for , and an illustrated monograph of the whole genus is published in the thesaurus conchyliorum, part i, by the author. it may be observed that in one of the new species, the notch in the peritreme almost disappears, leaving a very slight sinus. fig. , , , . purpura. auct. ("_the shell-fish from which purple is taken_," plin.) _fam._ purpurifera, lam. entomostomata, bl.--_descr._ oval or oblong, thick; spire for the most part short, sometimes rather longer; external surface generally sulcated, granulated, tuberculated or muricated; aperture long, oval, somewhat dilated, emarginated anteriorly; outer lip crenated, acute; columella flattened; operculum horny, with the nucleus lateral, thin towards the columella.--_obs._ true purpuræ to be found in the lamarckian genera buccinum, ricinula, and others. they may be generally distinguished by the flatness of the columellar lip, and by the short canal or emargination, which is not reflected or raised, as in buccinum. the species are very numerous and very variable in form, inhabiting the seas of temperate and tropical climates. the animals secrete a purple liquor, which has been used advantageously for dyeing; the origin of the famous tyrian dye. fig. , p. persica. purpurifera. lam. (_purpura_, purple; _fero_, to carry.) a family belonging to the second section of lamarck's order trachelipoda, the shells of which are described as having a very short recurved, or ascending canal, or else only a notch between the inner and outer lips. the name purpurifera has been given to the family because the animals which it includes, and particularly the genus purpura, contain the colouring matter from which the ancients obtained the well known splendid purple. this family contains the following genera. . cassis. outer lip thick, reflected, denticulated, canal turned suddenly over the back; spire short; including _cassidea_ and _cypræcassis_. fig. to . . cassidaria. canal turned gently upwards. fig. , . . oniscia. inner lip granulated; canal short. fig. . . buccinum. outer lip thickened not reflected; canal short; including _cyllene_ and _phos._ fig. , , , . . nassa. the same, with a notch or tooth at the extremity of the columella; including _cyclops_. fig. , . . dolium. swelled, grooved spirally; outer lip not reflected. fig. . . purpura. aperture large; columellar lip flat; including tritonidea. fig. , . . monoceros. the same, with a tooth on the outer lip. fig. . . concholepas. patelliform; aperture as large as the shell. fig. . . ricinula. columellar and outer lips granulated, denticulated, outer lip digitated; including _tribulus_. fig. . . trichotropis. hairs on the epidermis, along the keels. fig. . . terebra. elongated, with a spiral groove near the suture of the whorls. fig. . . bullia. short; aperture wide; outer lip marginated. fig. . . eburna. like buccinum, but the outer lip not thickened. fig. . . harpa. with varices at regular intervals. fig. . pusia. sw. a sub-genus of tiara (mitra.) (sw. malac. p. .) pusiodon. sw. a genus of "lucerninæ," sw. (helix) thus described: "shell flattened, smooth; the body-whorl large, and much dilated at the aperture; spire small, flat, of three or four contracted whorls; aperture very oblique, sinuated, or obsoletely toothed at the base of the outer lip, which is spreading and sub-reflected; inner lip obsolete; umbilicus open. zonaria chemn. . f. . auriculata zool. ill. i. pl. ." sw. malac. p. . pusiostoma. sw. a genus of the family "columbellinæ." sw. thus described: "general form of columbella, but the outer lip is only toothed in the middle, where it is greatly thickened; inner lip convex between the granular teeth; punctata, e. m. . f. . mendicaria, . f. . turturina, . f. . fulgurans. lam." sw. malac. p. . pustularia. sw. a genus of "cypræinæ," sw. thus described: "shell generally marked by elevated pustules; aperture narrow and linear; the extremities more or less produced; the teeth continued beyond, and frequently forming elevated striæ across the lips. p. cicercula, p. globulus." sw. malac. p. . pygmÆa. humph. columbella, auct. pyloridea. bl. the ninth family of the order lamellibranchiata, bl. the shells of which are described as nearly always regular, rarely otherwise, nearly always equivalve, gaping at both extremities; hinge incomplete, the teeth becoming gradually obsolete; two distinct muscular impressions; palleal impression very flexuous posteriorly. this family is divided into: section . ligament internal; pandora, thracia, anatina, mya, lutricola. section . ligament external; psammocola, soletellina, solen, sanguinolaria, solenocurtus, solenimya, panopæa, glycimeris, saxicava, byssomya, rhomboides, hiatella, gastrochæna, clavagella, aspergillum. pyramidal. (_pyramidalis._) resembling a pyramid in form. _ex._ cerithium telescopium, fig. . pyramidella. lam. (_a little pyramid._) _fam._ plicacea, lam. auriculacea, bl.--_descr._ pyramidal, smooth, polished; spire long, pointed, composed of numerous whorls; aperture small, modified by the last whorl, rounded anteriorly; outer lip slightly expanded; columella tortuous, with several folds. this is a genus of small, polished, marine shells. pyramidella terebellum, fig. . pyrazus. montf. potamis, brongniart. pyrella. sw. a genus consisting of turbinella spirilla, auct. and similar species, having a long channel, a pyriform outline, and one strong plait at the base of the columella, the apex of the spire is enlarged. p. spirillus, fig. . (the proper term would be spirilla.) pyriform. (_pyrum_, a pear; _forma_, shape.) shaped like a pear, i. e. large and rounding at one end, and gradually tapering at the other. _ex._ pyrula, fig. . pyrgo. defr. a genus of microscopic foraminifera. pyrgoma. auct. ([greek: purgos], _pyrgus_, a tower.) _order_, sessile cirripedes, lam.--_descr._ composed of a single conical, hollow paries, with a small aperture closed by an operculum of four valves, and supported upon a cup-shaped base.--_obs._ the genera into which leach has divided this genus are pyrgoma, adna, and megatrema; his genera nobia and savignium differ in having but two valves for the operculum. pyrgoma differs from creusia in having the body of the shell, i. e. the parietal cone, simple, not divided into valves. fig. . pyrgopolon. de montfort's figure of this genus appears as if it had been drawn from the nucleus of a belemnite. pyrula. auct. (_a little pear._) _fam._ canalifera, lam. siphonostomata, bl.--_descr._ thin, oblong, pyriform, ventricose towards the spire, gradually tapering towards the anterior of the aperture, spire short, consisting of few volutions; aperture wide, terminating in a long, narrow, open, canal; columella smooth, elegantly tortuous.--_obs._ the above description includes all the true fig shells, which present a most graceful form; the contour partaking of the peculiar curve, called by painters the line of beauty. p. ficus, fig. . pyrum. humph. pyrula, lam. quadrate. (_quadratus._) square, applied when the outline of shells is formed by nearly straight lines meeting at right angles. quadrilateral. four-sided. quinqueloculina. d'orbigny. a genus of microscopic foraminifera. radiating. (_radians._) a term applied to the ribs, striæ, bands of colours, &c. when they meet in a point at the umbones of a bivalve shell, and spread out towards the ventral margin.--_ex._ the bands of colour in tellina radiata, fig. . radicated. (_radix_, a root.) attached, and as it were rooted by means of a fibrous byssus. radiolata. lam. a family belonging to the order cephalopoda, lam. the shells belonging to it are described as discoidal, with the spire central, and the chambers radiating from the centre to the circumference. this family contains the genera rotalina, lenticulina, and placentula. radiolites. a genus belonging to the family of rudistes, differing from sphærulites, in having both the valves more conical. radius. montf. a genus composed of ovulum volva, auct. and other similar species, having a long attenuated canal at each extremity. fig. . radix. montf. a genus composed of species of limnÆa, having a short spire and wide aperture.--_ex._ l. aperta, fig. . ramified. (_ramus_, a branch.) branched out.--_ex._ the varices of some murices, &c. ramphidoma. schum. pollicipes, leach. ramose. (_ramosus_, branched.) spread out into branches. _ex._ murex inflatus, fig. . ranella. auct. (_rana_, a frog.) _fam_. canalifera, _lam._ siphonostomata, bl.--_descr._ oval or oblong, depressed, thick, with two rows of continuous varices, skirting the outline, one on each side; spire rather short, pyramidal, acute, aperture oval, terminating in a canal at each extremity; outer lip thickened within, crenulated, or denticulated, forming an external varix; inner lip spread over a portion of the body whorl.--_obs._ the shells composing this well-defined genus, are for the most part covered with tuberculations, and granulations, and from the colour and squat shape of some species, have been likened to frogs. the ranellæ are mostly inhabitants of the east indian seas. the few fossil species known, occur in the tertiary beds. the two continuous rows of varices skirting the spire, distinguish this genus from triton, which it nearly approaches, and into which some species run by imperceptible gradations. fig. , . many new species were brought to this country by mr. cuming, and are represented in parts , , , , , , of the author's conchological illustrations. rangia. desmoulins. gnathodon, gray. rapanus. schum.? a genus consisting of species of pyrula, auct. which are thin, much inflated, with short canals. fig. , p. papyracea. rapella. sw. a genus of "pyrulinæ," sw. thus described: "shell ventricose, generally thin, almost globose; the base suddenly contracted, and forming a short canal, the channel almost obsolete; umbilicus large, partly concealed by the inner lip. r. papyracea. en. méth. , f. ." sw. p. . rapanus, schum. fig. . raphanister. montf. a species of madrepore, described as a shell. rapum. humph. turbinella, lam. razor shell. a common name by which shells of the genus solen, are known in the market. rectilinear. (_rectus_, right; _linea_, a line.) in a straight line. _ex._ the hinge of byssoarca noæ, fig. . recurved. (_re_, back; _curvo_, to bend.) turned backwards; the term, when applied to symmetrical conical univalves, is used to signify that the apex is turned towards the posterior margin, as in emarginula, fig. . reflected. (_reflected_, to fold back.) turned, or folded backwards. _ex._ the edge of the outer lip in bulinus, fig. , is _reflected_, while that of cypræa, fig. to , is _inflected_. remote. (_remotus_, distant.) remote lateral teeth in a bivalve shell, are those that are placed at a distance from the cardinal teeth. _ex._ the lateral teeth of aphrodita, (fig. .) are remote; those of donax, (fig. ) are near. reniella. sw. a sub-genus of malleus. lardn. cyclop. malac. p. . gray states it to be only a distorted specimen of vulsella, syn. b. m. p. . reniform. (_ren_, a kidney; _forma_, shape.) shaped like a kidney. _ex._ the aperture of ampullaria, fig. . renulina. lam. a genus of microscopic foraminifera. reophax. montf. a genus of microscopic orthocerata, bl. repent. (_repens_, creeping.) a term applied to those shells, which, being attached by the whole length of their shell, give the idea of creeping or crawling. _ex._ vermilia, fig. . reticulated. (_reticulatus._) resembling net-work. retifera. bl. the first family of the order cervicobranchiata, bl. containing the genus patella. reversed or sinistral shells, are those in which the aperture is on the left side of the shell, while it is held with the mouth downwards, and towards the observer. _ex._ balea, fig. . attached bivalves are said to be reversed, when the left valve is free, instead of the right; a circumstance which sometimes occurs in chama and ostrea. rheda. humph. hyalÆa, lam. rhinoclavis. sw. a genus of "cerithinæ," sw. thus described: "channel curved backwards, in an erect position; inner lip very thick, with a tumid margin; pillar generally with a central plait; operculum ear-shaped; lineatum. en. m. , fig. , vertagus. ib. f. , subulatum. lam. no. , fasciatum. mart. , f. . obeliscus, en. méth. , f. ; aluco, ib. f. , (aberrant,) semi-granosum. ib. , f. , asperum. mart. , f. ." rhinocurus. montf. a genus of microscopic foraminifera. rhinodomus. sw. a genus of "scolyminæ," sw. thus described: no internal groove; shell clavate; the spire longer than, or equal with the aperture; the whorls with ridges or longitudinal varices, and rendered hispid by transverse grooves; inner lip wanting; pillar with a terminal fold; aperture striated; outer lip with a basal sinus. r. senticosus, chem. tab. . f. - . rhizorus. montf. a genus described from a microscopic shell, appearing to be a cylindrical bulla. rhodostoma. sw. a sub-genus of "turbininæ," sw. p. . rhomboidal. ([greek: rhomboeidos], _rhomboeidus_.) having a rhombic form, i. e. four-sided; two sides meeting at acute, two at obtuse, angles. conchologists are not very strict in the application of this term, for, indeed, a perfect rhomboidal figure could not be found among all the testaceous productions of the sea. rhomboides. bl. a genus described as resembling byssomya in the shell, but differing in the animal. mytilus rugosus, gmelin. hypogÆa barbata, poli. rhombus. montf. ([greek: rhombos], _rhombos_, a rhomb.) a genus consisting of species of conus, having a rhomboidal or quadrilateral form and a coronated spire. _ex._ conus nocturnus, fig. . ricinula. lam. (resembling the seed-vessel of the _ricinus_.) _fam._ purpurifera, lam. entomostomata, bl.--_descr._ sub-ovate, thick, tuberculated; spire short; aperture narrow, terminating anteriorly in a short canal; outer-lip thickened, denticulated within, digitated without; columellar lip spread over a portion of the body whorl, and granulated.--_obs._ this interesting genus is composed of some neat little shells allied to purpura, from which they are distinguished by the finger-like branching of the outer lip, and the granulations of the columella. fig. , r. horrida. right. see dextral. rimula. defr. a genus consisting of a minute species of emarginula, auct. which has a fissure near the margin, but not reaching it. r. blainvillii, fig. . rimulina. d'orbigny. a genus of microscopic foraminifera. ringicula. deshayes. a genus founded on auricula ringens of lamarck and several small fossils, resembling in some respects pedipes of adanson; they would belong to tornatella, were it not for the lips being thickened and marginated, fig. , a. ringens. rissoa. freminville. _fam._ ellipsostomata, bl. melaniana, lam.--_descr._ oblong, turrited, acuminated; spire long, consisting of numerous whorls; aperture round or oval, pointed posteriorly, dilated anteriorly; outer lip slightly thickened, emarginated, operculum horny.--_obs._ the rissoæ are small white, marine shells, considered by some authors as resembling melaniæ, but placed by sowerby near the scalariæ. they are principally from the shores of the mediterranean, and are also very abundant on the british shores, as well as the east and west indian. fig. , r. reticulata. robulus. montf. a genus of microscopic foraminifera. rollus. montf. a genus composed of conus geographus, auct. fig. , and other species, rather cylindrical in form, and having a coronated spire. rosalina. d'orb. a genus of microscopic foraminifera. rostellaria. (from _rostrum_, a beak.) _fam._ alatæ, lam. siphonostomata, bl.--_descr._ turrited, fusiform, thick, smooth or ribbed; aperture oval, terminating anteriorly in a long canal, posteriorly in a channel running up the spire; outer lip dilated, thickened, sometimes digitated, running up all or part of the spire, with a sinus near the anterior canal; inner lip smooth, spread over part of the body whorl and of the spire. the red sea and the indian ocean produce the few known species of this genus.--_obs._ hippochrenes is the name given by de montfort, to those fossil species which have the outer lip simple and very much dilated. r. curvirostrum, fig. . aporrhais is a name given to another proposed genus, composed of rostellaria pes-pelecani, auct. fig. . and similar species. rostrated. (from _rostrum_, a beak.) having one or more protruding points, as tellina rostrata. rotalia. lam. a genus of microscopic foraminifera. the same as rotalites of de montfort. rotella. lam. (_a little wheel._) _fam._ turbinacea, lam.--_descr._ orbicular, generally smooth, shining; spire conical, depressed, short; aperture subtrigonal; outer lip thin, angulated near the centre; inner lip spread over the surface of the whorls, forming a thickened disc. operculum horny, orbicular, spiral, with numerous whorls.--_obs._ the pretty little shells thus described are found in seas of tropical climates. they are distinguished from other genera of the family by their lenticular form and the orbicular callosity of the under surface. fig. , r. vestiaria. rudistes. lam. a family of the order conchifera monomyaria, lam. the shells of which are described as irregular, very inequivalve, without distinct umbones; the ligament, hinge and animal entirely unknown. the shells contained in this family may be thus distinguished. . calceola. large valve conical; attached by a flat space between the umbones, which form the extremities of the shell. fig. . . hippurites. large valve cylindrical, with two internal lobes or varices. fig. . . sphÆrulites. large valve attached, including _radiolites_. birostrites is proved to be the cast of a sphærulites. fig. , . . hipponyx. flat valve attached, upper valve conical. fig. , . rudistes. bl. the second order of the class acephalophora, bl. containing the genera sphærulites, crania, hippurites, radiolites, birostrites and calceola. rudolphus. lam. monoceros, auct. rufous. reddish brown. rugose. rough, rugged. rupellaria. fl. de belvue. an unfigured shell placed by de blainville in a division of the genus venerirupis. rupicola. fl. de belvue. a shell described by de blainville as an equivalve, terebrating species of anatina. a. rupicola, lam. sabinea. a genus of shells resembling small species of littorina, as l. ulvæ, &c. of our shores. saddle oyster. placuna sella, so called on account of a resemblance in shape to a saddle; the part near the umbones being flat, and the ventral margins being turned up in a sort of fluting or peak. sagitta. (_an arrow._) an ancient name for belemnites. salient. (_saliens._) jutting out, prominent. salpacea. bl. the second family of the order heterobranchiata, bl. containing no genera of shells. sandalina. schum. crepidulina, lam. a genus of microscopic foraminifera. sanguinolaria. lam. (_sanguis_, blood.) _fam._ nymphacea, lam. pyloridea, bl.--_descr._ equivalve, inequilateral, transverse, sub-ovate, rounded anteriorly, sub-rostrate posteriorly, compressed, thin, covered with a shining epidermis, gaping at the sides; hinge with two cardinal teeth in each valve, and an external ligament supported upon a prominent fulcrum; muscular impressions two in each valve, lateral, irregular, palleal impressions with a large sinus.--_obs._ this description is made to exclude some of lamarck's species of sanguinolaria, such as s. occidens, s. rugosa, which are psammobiæ; and to include others which he has left out. the sanguinolariæ are sub-rostrated posteriorly, while the psammobiæ are sub-quadrate and have a posterior angle. fig. , s. rosea. sandy shores of tropical climates. saracenaria. defr. a genus of microscopic foraminifera. savignium. leach. a genus of sessile cirripedes, described as composed of four valves soldered together, and a convex bivalve operculum; the ventral and posterior valve on each side being soldered together, in other respects resembling pyrgoma. fig. . saxicava. fl. de belvue. journ. de ph. an. . (_saxum_, a stone; _cava_, a hollow.) _fam._ lithophagidæ, lam. pyloridea, bl.--_descr._ transverse, irregular, generally oblong, inequilateral, sub-equivalve, gaping anteriorly; ligament external; muscular impressions two, lateral; palleal impression interrupted, not sinuated; hinge, when young with sometimes two or three minute, obtuse, generally indistinct, cardinal teeth; which become obsolete when full grown.--_obs._ several genera have been founded only upon the difference between the young and old shell of the same species of this genus. the saxicavæ are found in the little hollows of rocks; in cavities on the backs of oysters, of roots of sea-weeds, &c. in northern and temperate climates. s. rugosa, fig. . scabricula. sw. a sub-genus of mitræ, consisting of species which have a roughened external surface, &c. sw. malac. p. . scabrous. rough. scala. klein. scalaria, auct. scalaria. auct. _fam._ scalariana, lam. cricostomata, bl.--_descr._ turrited, oval or oblong; spire long, composed of rounded, sometimes separate whorls, surrounded by regular concentric ribs; aperture oval, peristome reflected continuous, entire.--_obs._ the typical species of this genus, commonly called the wentletrap, (s. pretiosa) is celebrated for the beautiful appearance caused by the numerous ribs encircling the whorls, and formerly produced an immense price in the market. it is brought from china. there are many smaller species, some of which are equally elegant. fig. , s. pallasii, kiener. scalariana. lam. a family belonging to the first section of the order trachelipoda, lam. the shells belonging to it are described as having the inner and outer lips continuous, without a canal, emargination, or other division. in this respect the family is stated to differ from the turbinacea, and is therefore separated. the genera may be distinguished as follows:-- . vermetus. irregularly twisted, like serpula. fig. . . eulima. pyramidal; apex contorted; including _bonellia_. fig. , . . rissoa. pyramidal, straight, consisting of few whorls. fig. . . scalaria. with external varices. fig. . . cirrus. trochiform. fig. . . enomphalus. orbicular. fig. . . delphinula. few whorls, rapidly increasing. fig. . scallop. the common name for shells of the genus pecten, the larger species of which were worn by pilgrims to the holy land in the time of the crusades. scalpellum. leach. (a little knife or lancet.) _order_, pedunculated cirripedes, lam.--_descr._ flat, quadrated, acuminated, composed of thirteen valves, one dorsal, arcuated; one pair apicial, acuminated; one pair ventral; two pair lateral, small, sub-quadrate; pedicle scaly.--_obs._ this genus and _smilium_, are the only pedunculated cirripedes which have thirteen valves; in the latter genus, which we think should at any rate be united to this, the valves are somewhat differently placed, and the pedicle is said to be smooth. fig. , scalpellum vulgare. british. scapha. klein. (_a boat._) navicella, auct. scaphander. montf. bulla lignaria, auct. fig. . scaphella. sw. a genus of the family "volutinæ," sw. thus described: "shell smooth, almost polished; outer lip thickened internally; suture enamelled; lower plaits the smallest; apex of the spire various: . fusiformis. sw. bligh. cat. . undulatus. _ex._ conch. pl. . . junonia, _ex._ conch. pl. . . stromboides. . papillosa. sw. sow. gen." sw. malac. p. . scaphites. (_a boat._) _fam._ ammonacea, lam. and bl.--_descr._ convolute, chambered, closely related to the ammonites, from which it differs in the last whorl being eccentrically straightened, and lengthened, and again incurved towards the extremity. only known in a fossil state. fig. , s. æqualis. scaphula. sw. a genus of "olivinÆ," sw. thus described: "spire very short, thick, obtuse, and not defined; aperture very wide, with only two or three oblique plaits at the base. sw. patula, _sow._ tank. cat. . (_b._)" (sw. p. .) scarabus. montf. (_scarabæus_, a kind of beetle.) _fam._ colimacea, lam. auriculacea, fer.--_descr._ oval, somewhat compressed, smooth, with slightly raised varices; spire equal in length to the aperture, pointed, consisting of numerous whorls; aperture ovate, rounded anteriorly, pointed posteriorly, modified by the last whorl; outer lip sub-reflected, with several prominent folds on the inner edge; inner lip spread over a portion of the body whorls, with several prominent folds.--_obs._ the shells of this genus are found like auriculæ, in marshy places. c. imbrium is said to have been found on the tops of mountains, by captain freycinet. fig. *, s. imbrium. schizodesma. gray. a genus composed of species of mactra, auct. with the ligament placed in an external slit. fig. , m. spengleri. scissurella. d'orbigny. (_scissus_, cut.) _fam._ turbinacea, lam.--_descr._ sub-globose, umbilicated, with a spiral groove terminating at the margin of the outer lip in a slit; spire short; aperture oval, modified by the last whorl; outer lip sharp, with a deep slit near the spire. recent on the coasts of britain; fossil in the calcaire-grossièr.--_obs._ this genus, consisting of small shells, is known from pleurotomaria by the shortness of the spire; the latter genus being trochiform. fig. , s. elatior. scolymus. sw. a genus of the family "scolyminæ." sw. (turbinella) thus described: "sub-fusiform, armed with foliated spines; spire shorter; pillar with distinct plaits in the middle." the species enumerated are, "cornigerus, pugillaris, globulus, rhinoceros, ceramicus, capitellum, umbilicaris, mitis." sw. malac. p. . scortimus. montf. a genus of microscopic foraminifera. scrobicularia. schum. species of lutraria, act. of a rounded shape. ligula, leach. scrobiculated. (_scrobiculus_, a little ditch or furrow.) having small ditches or furrows marked on the surface. scutella. brod. (_scutellum_, a little shield.) _fam._ phyllidiana, lam.--_descr._ shaped like ancylus, pearly within; apex posteriorly inclined, central, involute; muscular impressions two, oblong, ovate, lateral; aperture large, ovate.--_obs._ this genus is intermediate between ancylus and patella; while in the aspect of the beak, the observer is reminded of navicella. scutibranchiata. bl. (_scutum_, a shield; _branchiæ_, gills.) the third order of paracephalophora hermaphrodita, bl. containing animals with patelliform, but not symmetrical shells, and divided into the families otidea and calyptracea. scutum. montf. (_a shield._) parmophorus elongatus, lam. securiform. (_securis_, an axe; _forma_, shape.) hatchet-shaped. _ex._ pedum, fig. . sedentary annelides. lam. the third order of the class annelides, lam. distinguished from the two other orders by the circumstance of the animal being enveloped by a shelly tube which it never entirely leaves. the order is divided into the families dorsalia, maldania, serpulacea, and amphitrites. fig. to . sea date. the common name for pholas dactylus in the market, given to it on account of its cylindrical shape. fig. . segmentina. flem. nautilus lacustris, montagu. test. brit. planorbis nitidus, drap. tab. . fig. to . semicordate. half heart-shaped. semidiscoidal. forming the half of a circular disc. semilunar. half moon-shaped. senectus. humph. a genus of "senectinæ," thus described by swainson: "imperforate; the base produced into a broad flat lobe, spire rather elevated and pointed; the whorls convex; aperture perfectly round; not more oblique than _helix_; inner lip entirely wanting, imperialis. mart. . f. . marmoratus. l. m. . f. ." sw. p. . semiphyllidiana. lam. the second family of the order gasteropoda, lam. the genera of which are distinguished as follows:-- . umbrella, round, flat; apex central, muscular impression not interrupted. fig. . . pleurobranchus, apex lateral, sub-spiral. fig. . senoclita. schum. cineras, leach. septaria. lam. see teredo. septum. (lat.) an enclosure, applied to the thin plate of crepidula, fig. ; also to the plates dividing the chambers of multilocular shells. seraphs. montf. terebellum convolutum, lam. fig. . serpula. auct. (_a little serpent._) _fam._ surpulacea, lam.--_descr._ tubular, narrow, pointed at the apex, gradually widening towards the aperture, attached irregularly, sometimes spirally, twisted, imbricated; keeled or plain; aperture generally round, with the edge simple, or angulated by the termination of external ribs or keels.--_obs._ this description is intended to include the genera serpula, spirorbis, vermilia, galeolaria, &c. the serpulæ abound in all seas, on rocky shores, at any time covered by water, attached to any kind of marine substance, whether moveable or stationary. the fossil species occur in almost all tertiary strata. fig. to . serpulacea. lam. the fourth family of the order sedentary annelides, lam. containing the following genera of tubular, irregular shells. . serpula, attached by a small portion of the shell. fig. . . spirorbis, attached by the whole length, coiled. fig. . . galeolaria, with the open extremity raised, and the aperture tongue-shaped. fig. . . vermilia, attached by the whole length, straight or waved. fig. . . spiroglyphus, which hollows a bed in the body to which it is attached. fig. . sowerby. (genera of shells, published at , great russell street, bloomsbury,) gives satisfactory reasons for re-uniting the whole of the preceding under the name serpula. . magilus, which burrows in coral; outer lip reflected. fig. to . . leptoconchus, outer lip reflected. fig. . . stylifer, spiral, thin, globular, living in starfish. fig. , . the three last genera should certainly find some other place in the system. sessile cirripedes. lam. (_sessilis_, low, dwarfish.) an order of cirripedes, consisting of those which are attached by the base of the shells, containing the genera tubicinella, balanus, coronula, acasta, pyrgoma, creusia. to which may be added some other genera enumerated in explanation of figures to . the shells of the sessile cirripedes consist of two different sets of valves: st. the _parietal_ valves, or pieces arranged in a circle, side by side, around the body of the animal, (an arrangement designated _coronular_ by de blainville.) nd. the _opercular_ valves, or pieces placed so as to enclose the aperture. between those opercular valves the ciliæ protrude which characterize the class. besides these two sets of valves, there is generally a shelly plate, serving as a sort of foundation to the rest. the sessile cirripedes may be thus arranged. . tubicinella. six parietal valves, tube-shaped, opercular valves perpendicular. fig. . . coronula. six parietal valves, opercular valves horizontal. fig. , , , . these two genera fix themselves in the skin of the whale. the latter has been divided into the genera chelonobia, cetopirus, diadema, and chthalamus. . platylepas. valves divided, each having a prominent internal plate. fig. . . clitia. parietal valves four, opercular valves two, valves dove-tailed into each other. fig. . . elmineus. parietal valves four, opercular valves four. fig. . . conia. parietal valves four, thick and porous at the base. fig. . . octomeris. parietal valves eight. fig. . . catophragmus. parietal valves numerous, irregular. fig. . . balanus. parietal valves six; opercular valves four, placed against each other conically in pairs. this genus has been divided into acasta, conoplea, chirona, and balanus. fig. , , . . creusia. parietal valves four, supported on the edge of a funnel-shaped cavity. fig. . . pyrgoma. paries simple, supported on a cavity. this genus has been divided into the genera nobia, savignium, pyrgoma, adna, megatrema, and daracia. fig. to . setiferous. hairy. shank shell. the vulgar name for the shell designated murex rapa. it is used in ceylon for ornamental purposes. siderolites. montf. a genus of microscopic foraminifera. sigaretus. lam. _fam._ macrostomata, lam.--_descr._ suborbicular, oblique, haliotoid, thick; spire depressed, consisting of two or three rapidly increasing whorls; aperture wide, entire, modified by the last whorl, the width exceeding the length; columella tortuous; inner lip spread thinly over part of the body whorl; epidermis thin.--_obs._ this genus is distinguished from natica, by the width of the aperture, and the absence of the umbilical callosity. it may be known from stomatia, and stomatella, by the texture, which in sigaretus, is never pearly as in stomatia, the former being partly an internal shell. fig. , s. concavus. mostly brought from tropical climates. siliqua. megerle. (a husk, or pod.) leguminaria, schum. a genus composed of species of solen, auct. which have an internal rib. fig. , solen radiatus. siliquaria. brug. _fam._ cricostomata, bl. dorsalia, lam.--_descr._ tubular, rugose, spiral near the apex, irregularly twisted near the aperture, with a longitudinal fissure radiating from the apex, and proceeding through all the whorls and sinuosities of the tube.--_obs._ this genus was included in serpula by linnæus, from which, however, it is distinguished by the longitudinal slit, fig. . s. anguina. the recent species are found in the sponges with siliceous spiculæ, in the mediterranean; the fossils in tertiary beds. simple. (_simplex_, lat.) single, entire, uninterrupted, undivided. simplegas. mont. , . (_simplex_, simple; [greek: gastêr], _gaster_, belly.) a genus described by de blainville, as being discoidal, and having the spire uncovered like ammonites, but having the chambers divided, by simple septa, like nautilus.--_obs._ the septa of the shell named simplegas by de montfort, are evidently sinuous, according to his figure. fig. , s. sulcata. sinistral. (_sinister_, left.) on the left side. a sinistral shell is a _reversed_ one. the sinistral valve of a bivalve shell may be known, by placing the shell, with its ligamentary or posterior part towards the observer; the sides of the shell will then correspond with his right and left side. sinuous. winding, serpentine. the septa of ammonites are sinuous. the muscular impression of the mantle, or palleal impression of some bivalve shells, is sinuated near the posterior muscular impression. sinus. (_sinus_, a winding, or bay.) a winding or tortuous excavation. the sinus in the outer lip of strombus, fig. ; and that in the muscular impression of venus, will be indicated by the letter _s_. siphon. ([greek: siphon], siphon.) a pipe, or tube. a shelly tube passing through the septa of chambered shells. it is said to be _dorsal_, _central_, or _ventral_, according to its situation near the outer, or inner parts of the whorl. see introduction. siphonal scar. the name applied by mr. gray, to the opening or winding sinus in the palleal impression of a bivalve shell, in the place where the siphonal tube of the animal passes. siphonaria. sow. ([greek: siphon], siphon.) _fam._ phyllidiana, lam. patelloidea, bl.--_descr._ patelliform, depressed, inclining to oval, ribbed; apex nearly central, obliquely inclining towards the posterior margin; muscular impression partly encircling the central disc, but interrupted in front, where the head of the animal reposes, and at the side by a siphon, or canal passing from the apex to the margin.--_obs._ this siphon, which is in some species very distinct, serves to distinguish this genus from patella. s. sipho, fig. *. siphonobranchiata. bl. (_siphon_, and _branchiæ_, gills.) the first order of paracephalophora dioica, bl. divided into the families siphonostomata, entomostomata, and angiostomata. siphonostoma. guild. a sub-genus of pupa, consisting of several elongated species, which have the aperture detached from the whorls; such as p. costata, and fasciata. siphonostomata. bl. ([greek: siphon], _siphon_; [greek: stoma], _stoma_, mouth.) the first family of siphonobranchiata, bl. the shells of which are extremely variable in form, but always have a canal or notch at the anterior extremity of the aperture. this family partly answers to the canalifera of lamarck and the genus murex in the system of linnæus. it contains the genera pleurotoma, rostellaria, fusus, pyrula, fasciolaria, turbinella, columbella, triton, murex, ranella, and struthiolaria. siphuncle. (siphunculus.) a small siphon. sistrum. montf. ricinula, auct. fig. . skenea. _flem._ a genus including some species of euomphalus and cirrus. smilum. leach. _fam._ pedunculated cirripedes.--_descr._ thirteen pieces, ten of which are in pairs, lateral, subtriangular; one posterior dorsal, linear; all smooth; peduncle hairy.--_obs._ this genus is distinguished from pentelasmis, by the number of its valves, and from scalpellum, by the hairy peduncle. s. peronii, fig. . snail. the common garden snail, so destructive to our vegetables, belongs to the genus helix. the water snail, found in ponds, is planorbis. sol. humph. a genus consisting of several species of the genus trochus, and corresponding with the sub-genus tubicanthus, sw. malac. fig. . solarium. auct. (_a terrace, or gallery_.) _fam._ turbinacea, lam. goniostomata, bl.--_descr._ discoidal beneath, conical above, with a wide umbilicus, the spiral margin of which is angulated and crenulated; aperture trapezoidal; peritreme thin, sharp; columella straight; operculum horny, subspiral.--_obs._ the solarium perspectivum, is commonly called the staircase trochus, from the angulated edges of the whorls being seen through the umbilicus, which reaches to the apex, and presents the appearance of a winding gallery. the species are not numerous, they belong to tropical climates. a few fossil species occur in the tertiary formations. fig. , s. perspectivum. soldania. d'orb. a genus of microscopic foraminifera. solen. auct. (_a kind of shell-fish_, plin.) _fam._ solenacea, lam. pyloridea, bl.--_descr._ bivalve, transversely elongated, sub-cylindrical, equivalve, very inequilateral, gaping at both extremities, umbones terminal, close to the anterior extremity; hinge linear, with several small cardinal teeth, and a long, external ligament; muscular impressions distant, anterior tongue-shaped, placed behind the cardinal teeth, posterior irregular, sub-ovate; palleal impression long, bilobed posteriorly.--_obs._ the above description of the genus solen, is framed so as to admit only those species which are commonly called razor shells, with the umbones terminal, and the anterior muscular impression behind them. they are found buried deep in the sand, in a perpendicular position, their situation being pointed out by a dimple, on the surface. they are abundant in temperate climates. some of the lamarckian solenes will be found in the genus solenocurtus, bl. fig. , . solenacea. lam. a family of the order conchifera, dimyaria lam. the shells belonging to it are described as transversely elongated, destitute of accessary pieces, gaping only at the lateral extremities; ligament external.--the genera may be thus distinguished. . solen. razor shells, truncated at the extremities. fig. . . panopÆa. broad, with prominent tooth. fig. , . . solenocurtus. rounded at the extremities, with internal bar. fig. . . solenimya. no teeth, epidermis over-reaching the shell. fig. . . glycimeris. thick, fulcrum of the ligament prominent. fig. . . lepton. flat, scale-shaped. fig . . novaculina. umbones nearly central; covered by a thin epidermis. fig. . . glauconome. oval, margins close. fig. . solenella. sow. (_solen._) _fam._ arcacea, lam.--_descr._ oval, equivalve, subequilateral, compressed, covered with a thin, shining, olive-green epidermis; hinge with three or four anterior, and numerous sharp posterior lateral teeth, arranged in a straight line; muscular impressions two, lateral; palleal impression with a large sinus; ligament external, prominent, elongated.--_obs._ this genus partakes of the characters of the genus nucula, and of the family solenacea. a few specimens of the only species known (s. norrisii, fig. .) were dredged by mr. cuming at valparaiso. solenimya. lam. (solen and mya.) _fam._ mactracea, lau. pyloridea, bl.--_descr._ equivalve, inequilateral, transversely oblong, rounded at the extremities with the umbones near the posterior side, covered with a shining brown epidermis extending beyond the edges of the shell; hinge without teeth; ligament partly internal, placed in the margin of an oblique, flattish, posterior rib; muscular impressions two, distant, lateral. from the mediterranean, australian, and atlantic oceans.--_obs._ solenimya differs from solenocurtus and the true solens, in having the posterior side of the shell the shortest; in the internal ligament; and in being destitute of teeth. it resembles glycimeris, but is not incrassated. fig. , solenimya radiata. solenocurtus. bl. (_solen_ and _curtus_, short.) _fam._ pyloridea, bl. solenacea, lam.--_descr._ oval, elongated, equivalve, sub-equilateral, with the edges nearly straight and parallel, and the extremities rather truncated; umbones not very prominent, sub-central; hinge with or without two or three rudimentary cardinal teeth; ligament prominent, placed upon thick callosities; muscular impressions two, distant, rounded; palleal impression straight, with a deep sinus. east indies--_obs._ distinguished from the true solenes by the central position of the umbones and an internal bar reaching partly across the shell. soletellina. bl. sanguinolaria radiata. s. diphos, f. . s. livida of sowerby, and similar species, are placed together in this genus. spatha. lea. a sub-genus of iridinÆ, consisting of i. rubens and i. nilotica, which have not distinctly crenulated margins. spatha solenoides, of lea, is the genus mycetopus d'orbigny. fig. . sphÆnia. turt. a genus consisting of a small species resembling saxicava, in general appearance, but having a spoon-shaped process on the hinge of one valve. s. binghamii, fig. . sphÆroidina. d'orb. a genus of microscopic foraminifera. sphÆrulacea. bl. the first family of cellulacea consisting of the following genera of microscopic foraminifera: miliola, melonia, saracenaria, textularia. sphÆrulacea. lam. the fourth family of cephalopoda, lam. described as multilocular, globular, sphærical, or oval, with the whorls enveloping each other; some of them have a particular internal cavity, and are composed of a series of elongated, straight and contiguous chambers which altogether form a covering for the internal cavity. this family contains the genera miliola, gyrogona and melonia. sphÆrulites. lam. (_sphæra_, a sphere.) _fam._ rudistes, lam. and bl.--_descr._ orbicular, inequivalve, irregularly foliated outside; lower valve cup-shaped, depressed; upper valve nearly flat, like an operculum.--_obs._ these fossils are not regarded as shells by all conchologists. s. foliacea, fig. . sphincterulus. montf. lenticulina, bl. a genus of microscopic foraminifera. spines. (_spina_, a thorn.) thin, pointed spikes. spinose. (spinosus.) having spines or elevated points, as neritina spinosa. fig. . spiral. (_spira_, a spire.) revolving outwards from a central apex or nucleus, like the spring of a watch. a shell or an operculum, may be spiral, without being produced into a pyramid. bands of colour, striæ, grooves, &c. commencing from the nucleus and following the volutions of the shell, are described by the above word. spiramilla. bl. a genus of serpulacea, differing from other serpulæ principally in the characters of the animal. spiratella. bl. limacinea, lam. fig. . spire. (_spira._) the cone or pyramid produced in a non-symmetrical univalve by its oblique revolution downwards from the apex or nucleus. the spire, in descriptions, includes all the volutions above the aperture. see introduction. spirifer. sow. (_spira_, a spire; _fero_, to bear.) _order_, brachiopoda, lam.--_descr._ transverse, equilateral; hinge linear, straight, widely extended on both sides of the umbones, which are separated by a flat area in the upper and larger valve; this area is divided in the centre by a triangular pit for the passage of the byssus; interior with two spirally convolute appendages.--_obs._ this genus, which is only known in a fossil state, is distinguished from terebratula externally, by the flat area in one valve, internally, by the singular spiral process from which the above name is derived. fig. , . most of the species belong to the mountain or carboniferous limestone. spiroglyphus. daud. a genus consisting of a species of serpula _auct._ which makes a groove for itself in the surface of shells. serpula spirorbis, var. dillwyn. fig. . spirolina. lam. a genus of microscopic foraminifera. spiroloculina. d'orb. a genus of microscopic foraminifera. spirorbis. lam. a genus composed of species of serpula, auct. which are coiled round in a spiral disc like a snake at rest. s. nautiloides, fig. , is the common little white shell, found upon the shell of lobsters. spirula. (_spira_, a winding compass.) _fam._ lituolata, lam. lituacea, bl.--_descr._ convolute, smooth, symmetrical, discoid, with parallel unconnected whorls, divided into numerous chambers by transverse septa; siphon continuous.--_obs._ this pretty little shell is partly internal, only a part of it being visible when on the animal. fig. . spisula. gray. a genus composed of mactra fragilis, and other similar species, which have the ligament sub-external, marginal, not separate from the cartilage; with the posterior lateral teeth double in one valve, and single in the other. m. fragilis, fig. , is the species figured for spisula in mr. gray's paper on the mactradæ, in the second series of loudon's magazine of natural history. we have since learned, however, that it was figured there by mistake, not having been intended for a spisula, but belonging more properly to the genus mactra, as defined by mr. gray, whose description of spisula, is as follows:--"shell ovate, trigonal, sub-angular at each end. hinge and lateral teeth as in mactra, but hinge of left tooth small. siphonal inflexion ovate." the principal difference between spisula and mactra is, that the ligament is not separated from the cartilage in the former. spondylus. auct. (_a shell-fish_, ancients.) _fam._ pectenides, lam. sub-ostracea, bl.--_descr._ inequivalve, sub-equilateral, irregularly foliaceous and spinose, auriculated, denticulated at the margins, attached by the lower and deeper valve; hinge rectilinear, with two prominent teeth in each valve, locking into corresponding cavities in the opposite valve; umbones separated by a broad, elongated, triangular disc in the lower valve; ligament contained in a groove, dividing the triangular area in the centre; muscular impressions one in each valve, sub-central, sub-orbicular. the mediterranean, east and west indies, and china, produce spondyli most abundantly.--_obs._ this genus is remarkable for the richness and beauty of the spines and foliations, which adorn the external surface of most of the species, the splendid colours by which many of them are varied, and the natural groupings formed by their attachment to each other. fig. , and frontispiece. sporulus. montf. a genus of microscopic foraminifera. squamose. (_squama_, a scale.) scaly, covered with scales, as the pedicle of pollicipes mitellus, fig. *. stenopus. guild. ([greek: stenos], narrow, [greek: pous], foot.) a genus nearly "allied to the linnæan helices, from all of which it differs in the curious contraction of the pedal disc, and the caudal tentaculum furnished with a gland beneath." the shell is described as heliciform, umbilicated, transparent, with the aperture transverse. the two species described are stenopus cruentatus and lividus; they are both from the caribbæan islands, guild. zool. journ. xii. p. , tab. , f. to . stomatella. lam. see stomatia. stomatia. auct. ([greek: stoma], _stoma_, mouth.) _fam._ macrostomata, lam.--_descr._ sub-orbicular, oblong, auriform, variegated without, iridescent within; spire depressed; aperture entire, very wide, oblique; peritreme uninterrupted. _obs._ this genus is known from haliotis by being destitute of the series of holes; is distinguished from sigaretus by the substance of the shell, the latter being internal, and never pearly. our description includes stomatella, lam. the stomatiæ are marine, and belong to the east indies and new holland. fig. , s. phymotis. storillus. montf. , . a genus of microscopic foraminifera, included in the genus rotalites in m. de blainville's system. straparollus. mont. a genus containing some species of helix, auct. generic characters not defined. streptaxis. gray. _fam._ colimacea, lam.--_descr._ ovate, or oblong; when young, sub-hemispherical, deeply umbilicated, with rapidly enlarging whorls. at length the penultimate whorl is bent towards the right and dorsal side of the axis, and the umbilicus becomes depressed, and often nearly closed. the mouth is lunulate, the edge slightly thickened and reflected, and often with a single tooth on the outer side of the inner lip.--_obs._ this genus of land shells is separated from helix on account of the eccentricity of the penultimate whorl. s. contusa, fig. . striated. (_stria_, a groove.) marked with fine grooves or lines. strigocephalus. defr. pentamerus, sow.? gypidia, dalman. strombus. auct. _fam._ alatæ, lam. angiostomata, bl.--_descr._ oblong, turrited, rather ventricose, solid; aperture generally lengthened, terminating posteriorly in a short canal, and anteriorly in an emargination or truncated canal; outer lip, when young, thin; when full grown, thickened and expanded, lobed at the spiral extremity, sinuated anteriorly near the caudal canal.--_obs._ this well known genus includes some species of immense size, commonly called conch shells. most of the recent species are brought from the indian ocean. very few fossil species are known. the young shells have very much the appearance of cones, the outer lips being thin. there are also several species which do not, even when full grown, thicken their outer lips very considerably. the genus strombus is distinguished from rostellaria, by the notch in the outer lip, which in the latter genus is close to the canal. fig. , s. pugilis. strophomena. rafinesque. orthis, dalman. strophostoma. deshayes. a fossil shell, of the family of colimacea, lam. in some degree resembling anostoma, having the aperture turned upwards towards the spire, it is, however, umbilicated, and is said to have an operculum resembling that of cyclostoma. it is the ferussina of grateloup. fig. , , . struthiolaria. auct. (_struthio_, an ostrich.) _fam._ canalifera, lam.--_descr._ oblong, turrited, thick; spire turrited, composed of several angulated whorls; aperture oval, sub-quadrate, oblique; outer lip thickened, reflected, advancing in the centre, receding towards the extremities; inner lip thickened, expanded over the columella and part of the body whorl.--_obs._ this singular genus, consisting of three or four recent species, is named "pied d'autruche" by the french, on account of some resemblance in the outer lip to the foot of the ostrich. from new zealand. fig. , s. straminea. stylifer. brod. (_stylus_, a style; _fero_, to bear.)--_descr._ thin, pellucid, turbinated; apex a little out of the perpendicular; aperture wide anteriorly, gradually narrowing towards the spiral extremity, where it terminates acutely.--_obs._ this is a genus of small, transparent shells, found burrowing in the rays of starfish. there are but two or three species at present known, one of which is elongated like terebra, the other nearly globular. fig. , s. astericola. west indies, gallapagos, and britain. stylina. flem. stylifer, brod. sub. (_under._) used as a prefix and signifying nearly. thus a bivalve-shell, the valves of which are nearly alike, would be described as _sub_-equivalve. sub-aplysiacea. bl. the first family of the order monopleurobranchiata, bl. containing several genera of mollusca without shells, and the genus pleurobranchus. sub-bivalves. a term of distinction applied by de blainville, to those spiral univalves which have an operculum; these, as they constitute two distinct pieces, he considers as forming a medium between univalves and bivalves. sub-mytilacea. bl. the sixth family of the order lamellibranchiata, bl. the shells belonging to which are described as free, rather pearly, regular, equivalve; hinge dorsal, laminated; ligament external; two muscular impressions; palleal impression not sinuated. this family, with the exception of the last genus, agrees with the family nayades of lamarck, and contains the genera anodon, unio, and cardita. sub-ostracea. bl. the second family of lamellibranchiata, bl. the shells of which are described as of a compact texture, sub-symmetrical; with the hinge rather complex; one single, sub-central, muscular impression, without any traces of palleal impression. this family corresponds with the pectenides of lamarck, and part of the genus ostrea in the system of linnæus. it contains the genera spondylus, plicatula, hinnites, pecten, pedum, lima. sub-spiral. not sufficiently spiral to form a complete volution. subula. bl. (_an awl._) a generic name under which m. de blainville includes terebra maculata, auct. f. , together with nearly all the species of terebra, enumerated by lamarck and other authors; only leaving in the latter genus those species, which being more bulbous, or ventricose, nearly resemble buccinum in general form. these last mentioned species, such as terebra buccinoidea, (fig. ) have been formed into a new genus by mr. gray, under the name bullia. if both these genera were adopted, the genus terebra would be extinct. subulate. (_subula_, an awl.) a term applied to shells which are long and pointed as in terebra. fig. , . succinea. drap. (_succinum_, amber.) _fam._ colimacea, lam. limacinea, bl. _sub-genus_, cochlohydra, fer.--_descr._ ovate, rather elongated; aperture large, entire, longitudinal; spire short; outer lip thin, continuous with the thin, sharp-edged columella; inner lip spread over a part of the body-whorl.--_obs._ the shells belonging to this genus of partly amphibious mollusca, are distinguished from limnæa by not having a fold on the columella the s. amphibia is of a bright amber colour. fig. , . temperate and tropical climates. sulcated. (sulcatus, lat.) having grooves or furrows. sulci. grooves or furrows. suture. (_sutura_, lat.) a seam, stitch, joining together. applied particularly to the line which marks the joining of the whorls of the spire. the suture is distinguished as _simple_, as in most cases; or _double_, when accompanied by a parallel groove close to it; _marginated_, when produced into a ledge by the matter which fills up and covers it; _obsolete_, when it is filled up so as not to be visible, as in the case of ancillaria. sylvicola. humph. cyclostoma, lam. symmetrical, ([greek: sun], _syn_, similar; [greek: metron], _metron_, proportion.) both sides alike. although the term is used thus as one of distinction, it is to be observed that no shells are strictly and perfectly symmetrical; even in the nautilus, the apex verges in a slight degree towards one side of the shell. two kinds of univalve are symmetrical, or nearly so; st. those which are symmetrically convolute, as the nautilacea and the ammonacea, which are spiral; nd. those which are not spiral, but simply conical, as the patelliform shells. bivalves belonging to the brachiopoda are also symmetrical. _ex._ patella, fig. . ammonites, fig. . symphynota. lea. a genus of nayades, in which mr. lea proposed to include species of the genus unio, the valves of which are connate, or united at the dorsal margin. we believe that this distinction, as a genus, has been abandoned by its author. the fact is, that all the uniones are symphynotæ when in a young state. in unio alatus, (fig. ) and dipsas plicatus, (fig. ) it will be observed that the valves have not separated at the dorsal edge, but are broken lower down. tapada. (gray. turton. p. .) a division of the genus helix, containing helix aperta, auct. or the tapada snail. tapes. schum. pullastra. sow.? tectus. montf. a genus composed of species of the genus trochus, having elevated, conical spires, and columella notched or truncated by a spiral fold. fig. . trochus maculatus, presents an example. telebois. montf. a genus of microscopic foraminifera. telescopium. montf. cerithium telescopium, auct. fig. . tellina. linn. _fam._ nymphacea, lam. conchacea, bl.--_descr._ sub-equivalve, inequilateral, compressed, rounded anteriorly, slightly beaked or angulated posteriorly, the posterior ventral margin having a flexuosity; hinge with two cardinal and generally two lateral teeth in each valve; muscular impressions, two in each valve, remote; palleal impression with a large sinus.--_obs._ the fold or bending in the posterior margin distinguishes this genus from others which it nearly resembles. it is composed of some bivalves of great beauty and variety, which are found in nearly all climates. fig. , t. radiata, , t. lingua-felis. tellinides. lam. _fam._ nymphacea, lam.--_descr._ sub-equivalve, inequilateral, transverse, compressed, rounded anteriorly, slightly beaked or angulated posteriorly; hinge with two cardinal teeth in each valve, and one lateral tooth in one valve, very near the cardinal teeth. muscular impressions two, distant, palleal impression with a large sinus. _obs._ this genus is distinguished from tellina in having but one lateral tooth near the cardinal teeth. fig. , t. rosea. tropical. tenuipedes. (_tenuis_, slender; _pedes_, feet.) the second section of the order conchifera dimyaria, divided into the families mactracea, corbulacea, lithophagidæ, nymphacea. teraclita. schum. conia, auct. terebellum. lam. (_terebra_, an augur?) _fam._ convolutæ, lam. angyostomata, bl.--_descr._ smooth, slender, oblong, sub-cylindrical; spire obtuse, short, sometimes hidden; (seraphs, montf.) aperture long, narrow posteriorly, wider anteriorly; outer lip slightly thickened, truncated, unconnected at the base with the columella; inner lip thin, smooth, nearly straight, spread over a portion of the body-whorl, continued in a ridge above the sutures of the spire.--_obs._ montfort has separated the fossil species with hidden spires, under the name seraphs. (t. convolutum, lam.) only one recent species is known, of which there are several varieties, one spotted, one marked in sub-spiral lines, another in patches. it is brought from the east indies. fig. , t. convolutum; , t. subulatum. terebra. (_an augur, a piercer._) _fam._ purpurifera, lam. entomostomata, bl.--_descr._ subulate, elongated, pointed, turrited; spire long, consisting of numerous whorls; aperture small terminating in a short, reflected canal; outer lip thin; columella tortuous; operculum horny. the recent species are mostly tropical.--_obs._ nearly all the species enumerated by lamarck and other authors are included by de blainville in his genus subula; those few species which that conchologist left in the present genus, being shorter and more ventricose than the others, approximate in shape to some of the buccina, and are distinguished by mr. gray under the generic name bullia. it seems strange, that de blainville, being convinced of the necessity of separating the two groups, and consequently applying a new generic term to one of them, should have given that term to the larger number and the more typical species of the lamarckian genus. fig. , bullia vittata. (terebra.) fig. , terebra maculata. (subula.) terebralia. sw. a genus of "cerithinæ," sw. thus described: "outer lip much dilated, generally uniting at its base to the inner lip; leaving a round perforation at the base of the pillar; channel truncate; operculum round: palustre. mart. f. ." sw. p. . terebrating shells. (_terebro_, to pierce.) shells which reside in holes pierced in rocks, wood, &c. by means of some corrosive secretion of the animal. _ex._ pholas, teredo, &c. terebratula. brug. (_terebrans_, bored.) _fam._ brachiopoda, lam.--_order._ palliobranchiata, bl.--_descr._ inequivalve, equilateral, oval or sub-trigonal, ventricose or compressed, attached by a tendon passing through an opening in the dorsal, or upper and larger valve, the umbo of which advances beyond that of the other valve; hinge destitute of a ligament, with two teeth in the dorsal valve, locked into corresponding cavities in the ventral, or lower valve, and with two curious processes originating at the umbo of the lower valve, presenting, in some species, the appearance of fine winding tape, advancing towards the front of the valve, and again receding to the centre, where the ends unite; muscular impressions two, placed near the centre of each valve.--_obs._ the terebratulæ are included in the genus anomia in the system of linnæus. the recent species are not very numerous--they are found in all climates. the fossil species are more numerous than the recent ones, occurring in the secondary and tertiary formations. t. psittacea, fig. . teredina. (from teredo.) _fam._ tubicolæ, lam. adesmacea, bl.--_descr._ valves equal, inequilateral, with prominent umbones, as it were soldered to the outside of the rounded end of a shelly tube, of which they form a part; aperture of the tube partly divided; a flat accessary valve placed on the umbones.--_obs._ this genus, which is only known in a fossil state, is distinguished from teredo, by the valves being fixed on the tube, and the tube being closed at one extremity. fig. , , t. personata. teredo. auct. (_a piercer._) _fam._ tubicolæ, lam. adesmacea, bl.--_descr._ valves equal, inequilateral; presenting when closed, an orbicular figure, with a large angular opening in front, and a rounded opening at the back; placed at the anterior extremity of an irregular, flexuous, elongated tube, open at both ends; the anterior termination divided in a double aperture opened and closed at the will of the animal by two opercula.--_obs._ this genus of molluscous animals, is remarkable for boring holes in wood, which are filled by their elongated tubes, and give it a honey-comb appearance. fig. . t. navalis. fig. , a piece of bored wood. terminal. when the umbones of a bivalve shell are placed at or near the extremity, as in mytilus, fig. , pinna, fig. , they are said to be _terminal_. the same term is also applied to the nucleus of an operculum, when it forms an extreme point, or is close to one of the edges. tessellated. (wrought in chequer-work). a term applied to the colouring of shells, when arranged in regular defined patches like a tessellated pavement. testacella. (_testa_, a shell.) _fam._ limacinea, lam. and bl.--_descr._ haliotoid, compressed; aperture wide, oblique; columella flat, oblique; spire short, flat, consisting of less than two whorls.--_obs._ this shell which is extremely small compared with the animal, is placed upon its back, near the posterior extremity. the animal is found in some of our gardens, and very much resembles the common garden slug. fig. , t. haliotoidea. testaceous. (_testa_, a shell.) shelly. testaceous mollusca, are soft animals having shells. a testaceous operculum is one composed of shelly matter. tetracera. bl. the first family of the order polybranchiata, bl. containing no genera of testaceous mollusca. textilia. sw. a sub-genus of conus, consisting of conus bullatus, &c. sw. malac. p. . textularia. defr. a genus of microscopic foraminifera. thalamus. montf. a genus described as resembling conilites, but curved and granulated. thallepus. sw. a genus of "aplysianiæ," sw. thus described: "body more slender and fusiform;" (than aplysia,) "the lobes of the mantle short, and incapable of being used for swimming; tentacula two, large, ear shaped; eyes not visible. t. ornatus, _sw._ sp. nov." sw. p. . thallicera. sw. a generic name under which swainson distinguishes ampullaria avellana, auct. thecidium. (_thecas_, a box.) _fam._ brachiopoda, lam. _order_, palliobranchiata, bl.--_descr._ lower valve concave, sub-trigonal, with the umbo produced into a triangular, slightly incurved beak, and with two short, pointed processes advancing from beneath the umbones; upper valve flat, rounded square, with a short, blunt appendage, formed to fit between the tooth-like process of the other valve; its inner surface ornamented with symmetrically curved ridges. thecosomata. bl. the first family of the order aporobranchiata, bl. containing the genera hyalæa, cleodora, cymbulia, pyrgo. theliconus. sw. a sub-genus of conus. lardn. cyclop. malac. p. . thelidomus. sw. a generic name under which swainson has described a division of the genus helix, and which he has also used to designate a genus in the family of "rotellinæ," founded upon an aggregate of loose particles collected and agglutinated in a spiral form by the larva of an insect. sw. malac. p. and . themeon. montf. a genus of microscopic foraminifera. theodoxus. montf. a division of the genus nerita. fig. , n. virginea. thetis. sow. (_a sea nymph._) a genus of fossil shells, described as resembling mactra, but not having the internal ligament, and having several small, acuminated, cardinal teeth, but no lateral teeth. it resembles tellina in some degree, but has not the posterior fold. thiarella. sw. a sub-genus of mitra, lardn. cyclop. malac. p. . thracia. leach. _fam._ lithophagidæ, lam. pyloridea, bl. a genus described as intermediate between anatina, and mya, and in some degree resembling corbula. t. corbuloides, fig. . thunder-stones. one of the vulgar appellations which have been applied to shells of the genus belemnites. thiatyra. leach. a genus composed of amphidesma _flexuosa_, lam. and similar species, belonging more properly to the genus lucina. tiara. sw. a genus of "mitranæ," sw. thus described: "aperture narrow, linear, or of equal breadth throughout; outer lip and base of the body whorl contracted, the former generally striated; an internal canal at the upper part of the aperture; shell (typically) turrited, and equally fusiform; representing the _muricidæ_ and cymbiola." sw. malac. p. . the principal difference between tiara and mitra appears to be that in the latter, the aperture is more linear and contracted in the centre. mitra episcopalis is an example. tinoporus. montf. a genus of microscopic foraminifera. tiranites. montf. a division of the genus baculites. tomella. sw. a genus of "pleurotominæ," sw. thus described: "fusiform, smooth; the spire of very few whorls, and not longer than the channel; inner lip with a thick callosity at the top; the slit short and wide; lineata, en. méth. , f. , clavicularis, ib. f. . filosa. en. méth. , f. . lineolata. ib. f. ." sw. p. . tomogerus. montf. anastoma, auct. fig. . tonichia. gray. syn. b. m. p. . a genus composed of those species of chiton which have the margin smooth. tornatella. auct. _fam._ plicacea, lam.--_descr._ oval, spirally grooved; spire short, rather obtuse, consisting of few whorls; aperture long, narrow, rounded anteriorly; outer lip simple; inner lip thin, slightly spread, columella spiral, incrassated, confluent with the outer lip. the recent species are few. several fossil species occur in london clay, inferior oolite and calcaire-grossièr. monoptygma, lea, resembles this genus, but has a fold on the inner lip. fig. , t. solidula. tortuous. (_tortuosus_) twisted. this adjective is sometimes applied as a specific name; as arca tortuosa. trachelipoda. lam. ([greek: trachêlos], _trachelos_, a neck; [greek: poda], _poda_, foot.) the third order of the class mollusca, in the system of lamarck. the trachelipodous mollusca are described as having the posterior part of the body spirally twisted and separated from the foot; always enveloped in a shell. the foot is free, flat, attached to the base of the neck. shell spiral, and enclosing the animal when at rest. this order contains the families, colimacea, lymnacea, melaniana, peristomiana, neritacea, janthinea, macrostomata, scalariana, plicacea, canalifera, alata, purpurifera, columellaria, convolutæ. the genera belonging to these families, are represented in the plates, fig. , to . transverse. (crosswise.) a shell is said to be transverse, when its width is greater than its length, that is, when it is longer from one side to the other than from the umbones to the ventral margins. the term is applied by some authors to express the direction of the lines of growth in bivalve shells, and the spiral lines in spiral shells. see concentric. trapezium. meg. cypricardia, lam. trapeziform, or trapezoid. ([greek: trapezion], _trapezion_, _trapezium_; [greek: eidos], _eidos_, form.) having four unequal and unparallel sides. _ex._ cucullæa, fig. . tribulus. klein. ricinula, lam. trichotropis. brod. and sow. ([greek: trichos], _trichos_, hair; [greek: tropis] _tropis_, keel.) _fam._ purpurifera, lam.--_descr._ turbinated, keeled, thin, umbilicated; aperture longer than the spire, entire; columella obliquely truncated; outer lip thin, sharp; epidermis horny, produced into long hairs at the angles of the shell; operculum horny, with the nucleus lateral.--_obs._ although the shells of this genus have something of the shape of turbo, they are distinguished from that genus at once by the thinness of the shell. they are also known from buccinum, by the absence of a canal. only two or three species are known, which belong to the northern and arctic oceans. t. bicarinata, fig. . tridacna. auct. _fam._ tridacnacea, lam. chamacea, bl.--_descr._ equivalve, regular, inequilateral, radiately ribbed, adorned on the ribs with vaulted foliations, waved at the margins, with a large, anterior hiatus close to the umbones, for the passage of a large byssus, by which the animal fixes itself to marine substances; hinge with a partly external ligament; two laminar teeth in one valve, one in the other.--_obs._ the beautiful shells composing this genus are of a delicate white colour, tinged with buff. one species, the t. gigas, attains a remarkable size, measuring from two to three feet across, and weighing five hundred pounds. tridacna is distinguished from hippopus by the large opening in the hinge. t. elongata, fig. . tridacnacea. lam. a family belonging to the first section of the order conchifera dimyaria, lam. described as regular, equivalve, solid, and which are remarkable for the deeply sinuated or undulated ventral margin. this family contains the genera: . hippopus. valves closed at or near the hinge. fig. . . tridacna. an hiatus near the hinge. fig. . tridentate. (_tridentatus_.) having three teeth, or salient points. _ex._ hyalæa tridentata, fig. . trigona. schum.? triangular species of cytherea, such as c. lævigata, triplas corbicula, ventricosa, bicolor, &c. fig. _b._ trigonacea. lam. a family belonging to the order conchifera dimyaria, containing the genera trigonia and castalia, the latter of which ought to be removed to the nayades. fig. , . trigonal. triangular, having three sides. trigonella. humph. mactra, auct. trigonia. brug. ([greek: trigônon], _trigonon_, triangular.) _fam._ trigonata, lam. camacea, bl.--_descr._ equivalve, inequilateral, transverse, sub-trigonal, costated and granulated without, pearly and iridescent within, denticulated on the inner margin, rounded anteriorly, truncated posteriorly; hinge with four oblong, compressed, diverging teeth in one valve, receiving between their grooved sides, two similar teeth in the other; ligament external, thick; muscular impressions two in each valve.--_obs._ only one recent species of this marine genus is known, the t. pectinata, which comes from new holland; and was formerly so rare, that a much worn odd valve has been sold for a considerable sum. it is of a brilliant pearly texture within, tinged with purple or golden brown. fossil species occur in lias, upper and lower oolite, and green-sand. t. pectinata, fig. . trigonosemus. könig. a genus composed of species of terebratula, auct. which have one valve produced into a beak, perforated, or as it were truncated at the apex. t. lyra, fig. , differing from terebratula lyra, lam. trigonostoma. a sub-genus of helix, with a trigonal aperture. gray's turton, p. . trigonotreta. könig. a genus composed of species of terebratula, auct. which have the hinge of the larger valve produced into a triangular disc, divided by a triangular foramen in the centre. spirifer, sowerby, belongs to this genus. fig. , . trilobate. ([greek: treis] three; [greek: lobos], division, lobe.) divided into three lobes or principal parts. ex. malleus, fig. . triloculina. d'orbigny. a genus of microscopic foraminifera. tripartite. (_tripartitus_) composed of or divided into three separate parts. triphora, or tristoma. deshayes. a genus composed of small reversed species of cerithium, auct. which have the anterior canal closed at the anterior of the aperture, but opened at the extremity, and a small tubular opening on the upper part of the whorls, making three openings on the body whorl. this genus stands in the same relation to cerithium as the typhis to murex. fig. in the old plates, and fig. in the new plates. triplex. humph. murex, linn. triplodon. spix. hyria, auct. triptera. quoy et gaimard, cuviera, fer. described in the voyage de la coquille, and represented as a molluscous animal destitute of a shell. triquetra. bl. triangular species of venus auct. trisis. oken. arca tortuosa, auct. tristoma. described as triphora. triton. auct. _fam._ siphonostomata, bl. canalifera, lam.--_descr._ oblong or oval, thick, ribbed or tuberculated, with discontinuous varices placed at irregular distances; spire prominent, mammillated; aperture round or oval, terminating anteriorly in a generally long, slightly raised canal; columellar lip granulated or denticulated; outer lip thickened, reflected, generally denticulated within; epidermis rough; operculum horny.--_obs._ however nearly allied the tritons may appear to be to the murices and ranellæ there are still to be traced in the shells of each of those genera, several constant and well marked distinctions, by which they maybe at once recognized. in the ranellæ, the varices run in two rows along the spire; in the murices, they form three or more rows; but in the tritons, they do not follow each other, _i.e._ they do not occur in the same part of each volution. the large species of triton, are sometimes used as trumpets. the tritons are brought from the mediterranean, ceylon, the east and west indies, and south seas. fig. to . tritonidea. sw. a genus of "buccininæ," sw. thus described: "shell bucciniform, but the basal half is narrowed, and the middle more or less ventricose; spire and aperture equal. pillar at the base with two or three obtuse and very transverse plaits, not well defined; outer lip internally crenated and with a superior siphon; inner lip wanting, or rudimentary." this genus is the same as the one first distinguished by mr. gray under the name of pollia. we do not regret the discovery made by mr. swainson of that name being previously occupied for a genus of lepidopterous insects. fig. , represents tritonidea articularis. (pollia, gray.) trivia. gray. a genus composed of those small species of cyprÆa, auct. which are characterized by small ridges on the dorsal surface, and have the anterior of the columella internally concave and ribbed. c. pediculus. auct. fig. , . trochatella. sw. a sub-genus of helicinæ, consisting of those species which are acute and trochiform. trochia. sw. a genus of the family buccininæ, thus described: "shape intermediate between purpura and buccinum; whorls separated by a deep groove; inner lip when young, depressed, when adult, thickened, convex and striated; basal canal very small. t. sulcatus. e. m. . f. ." sw. malac. p. . trochidon. sw. a sub-genus of "trochinæ," sw. lardn. cyclop. malac. p. . trochilÆa. sw.? pileolus, auct. trochurus. humph. monodonta. lam. trochus. auct. (_a top._) _fam._ turbinacea, lam. goniostomata, bl.--_descr._ turbinated, thick, striated, tuberculated or smooth; spire elevated, conical, consisting of numerous whorls; under surface discoid; aperture more or less depressed in an oblique direction, generally angular; columella arcuated, more or less prominent at its union with the outer lip, contiguous to the axis of the shell; operculum horny, orbicular, with numerous whorls.--_obs._ lamarck distinguished this genus from turbo by the general form, which is more conical, and the aperture, which is angulated, while that of turbo is rounded. monodonta or odontis is only separated on account of the notch at the termination of the columella. but these characters glide so imperceptibly from one genus to the other, that there is no line of demarcation to be found but in the operculum. accordingly, sowerby (in gen. of sh. .) has stated his reasons for considering as trochi, all the species which have horny opercula; and as turbines, all those which have testaceous opercula. fig. to . the trochi are found in all climates. tropÆum. sow. crioceratites. trophon. montf. murex magellanicus, auct. and several other species which belong more properly to fusus than to murex. trumpet shell. a large species of triton (variegatus), used by natives of south sea islands as a trumpet, to call warriors and herds of cattle together. it answers the purpose tolerably well, producing a very sonorous blast. truncated. (_truncus_, cut short.) terminating abruptly, as it were cut short. _ex._ solenensis, fig. . truncatulana. d'orb. a genus of microscopic foraminifera. truncatella. risso. a genus composed of several species of land shells which have been confounded by some authors with cyclostoma. the genus is thus described: "shell turriculated, cylindrical, decollated or truncated at the apex, no epidermis; aperture oval, short, with lips continuous, simple." _ex._ truncatella truncatulina, lowe, zool. journ. t. . p. . our plates, fig. , . it is found on the shores of britain, the mediterranean, and west indies. tuba. lea. a genus of small fossil shells, described as resembling turbo, but with the aperture more like that of melania. lea. contrib. geol. tubercle. (_tuberculus._) a small swelling excrescence, or knob. tuberculated. having a number of small lumps or pimples, as turrilites, fig. . tubicinella. lam. (_tubicen_, a trumpeter.) _order_, sessile cirripedes, lam.--_descr._ a cylindrical tube, composed of six elongated valves jointed together side by side, striated longitudinally, surrounded by concentric rings; aperture circular, enclosed by an operculum of four valves, placed perpendicularly in an epiphragm.--_obs._ the tubicinellæ are found with nearly the whole shell buried in the thick skin of the whale. t. balænarum. tubicolaria. lam. (_tuba_, a tube; _cola_, an inhabitant.) a family of the order conchifera dimyaria, lam. consisting of bivalves soldered as it were within, or connected with, a testaceous tube. the genera contained in this family may be thus distinguished. . aspergillum. valves fixed, tube perforated and fringed. fig. . . teredina. valves fixed, prominent, tube closed at one end. fossil. fig. , . . clavagella. one valve fixed, the other free. fig. . . teredo. both valves free, tube open at both ends. fig. , . . fistulana. valves free, tube closed at one end, straight, long. fig. , . . gastrochÆna. valves free, tube closed at one end, short, bulbous. fig. . tubivalves. bl. shells composed of two valves connected in a tube, corresponding with the family tubicolæ of lamarck. tuliparia. sw. a sub-genus of "coronaxis," sw. lardn. cyclop. malac. p. . turbinacea. bl. the sixth family of polythalamacea, bl. containing the genera cibicides and rosallites, microscopic foraminifera. turbinacea. lam. a family of the first section of the order trachelipoda, lam. containing the following genera. . solarium. with umbilicus reaching to the apex; including _bifrontia_ and _orbis_. fig. to . . rotella. a callosity on the under side. fig. . . phasianella. oval; operculum shelly. fig. . . planaxis. columellar lip flat; aperture notched. fig. . . turbo. top-shaped; mouth generally round; operculum shelly. fig. . . trochus. top-shaped; mouth generally angulated; operculum horny, consisting of many whorls; including _elenchus_. fig. , , . . margarita. operculum horny, consisting of few whorls; pearly. fig. . . littorina. similar, not pearly; including _assiminnea_. fig. , *. . phorus. attaching dead shells, stones, &c. fig. . . monodonta or odontis. a notch and prominent point at the lower part of the aperture. fig. . . lacuna. with an umbilicus. fig. . . turritella. elongated, screw-shaped. fig. to . turbinated. (_turbo_, a top,) top-shaped. the term is applied generally to those shells which are large at one extremity, and narrow to a point at the other. _ex._ trochus, fig. ; turbinellus, fig. . turbinellus. auct. (_a little top._) _fam._ canalifera, lam. siphonostomata, bl.--_descr._ turbinated, thick, wide near the apex, generally tuberculated; spire short, depressed, mammillated; aperture rather narrow, terminating anteriorly in an open canal; outer lip thickened within; columella having from three to five prominent, compressed, transverse folds. the species of this genus are mostly tropical.--_obs._ the turbinelli are a well marked genus of marine shells, the species of which are numerous. no fossil species are known. the genus cancellaria makes the nearest approach to turbinellus in some characters, but may be distinguished by the roundness of its form, the raised lines inside the outer lip, and the obliquity of the folds on the columella. fig. to . turbo. auct. (_a top._) _fam._ cricostomata, bl. turbinacea, lam.--_descr._ turbinated, solid, ventricose, generally grooved or tuberculated; spire short, pointed; aperture generally rounded, sub-effuse anteriorly, entire; operculum shelly, solid, incrassated on the outer side, horny and sub-spiral on the inner side. the turbines are mostly tropical.--_obs._ the only certain means of distinguishing this extensive genus of marine shells from trochus, is the operculum, which in the latter genus is horny, spiral, and composed of a great number of whorls. the trochi, however, are in general more conical, and flatter at the under side of the whorls, and this constitutes lamarck's distinction between the genera. t. setosus, fig. . turgid. (_turgidus._) puffed up, swollen, inflated. this term is applied synonymously with ventricose. turricula. humph. melania, auct. turriculacea. bl. the seventh family of the order polythalamacea, bl. containing the genus turrilites, fig. . turrilites. lam. (_turris_, a tower; [greek: lithos], a stone.) _fam._ turriculacea, lam. ammonacea, bl.--_descr._ chambered, turrited, spiral; septa sinuous and lobate, perforated by a siphon; aperture rounded, with the outer lip expanded. this genus, which is distinguished from the other ammonacea by having the spire produced, _i. e._ not being convolute, consists of several species, occurring only in chalk-marl. fig. . turris. montf. a genus composed of those species of mitra, auct. which have the whorls angulated, with the aperture lengthened and undulated. turrited. the spire of an univalve shell is said to be _turrited_ when the whorls of which it is composed are regulated so as to have the appearance of little turrets rising above each other, as in mitra, fig. . turritella. lam. (_a little tower._) _fam._ turbinacea, lam. cricostomata, bl.--_descr._ turrited, elongated, generally grooved spirally; spire pointed, consisting of numerous whorls; aperture rounded or angulated; inner and outer lips thin, confluent anteriorly; operculum horny.--_obs._ the shells composing this well defined genus, are commonly called screws, a name to which the spiral grooves of most of the species seems to entitle them. fig. , t. imbricata. tympanostoma. schum. (_timbrel mouth._) potamis, brongn. typhis. montf. a genus composed of murex tubifer, auct. and other similar species, which have the canal closed and a perforated tube between each varix on the angulated part of the whorls. besides the fossil species originally described, there are now five species known, which are figured in part , of the conchological illustrations by the author. typhis tubifer, fig. . ultimus. montf. (_the last._) a genus composed of ovulum gibbosum, auct. fig. , and other species in which the canals are not distinctly defined, nor elongated. this fanciful name is given to the genus on account of its being described in the last page of the book. umbilicated. (_umbilicatus._) having an umbilicus, as nautilus umbilicatus. umbilicus. (_a navel._) the hollow formed in spiral shells when the inner side of the volutions do not join each other, so that the axis is hollow. the umbilicus is marked with the letter u in helix algira, fig. . the term is also used to express any small, neat, rounded hollow. umbo. (_the boss of a buckler or shield._) the point of a bivalve shell above the hinge, which constitutes the apex or nucleus of each valve, from which the longitudinal rays diverge, and the lines of growth, commencing at the minutest circle, descend in gradually enlarging concentric layers to the outer margin. the umbones will be marked with the letter _u_, in cytherea, fig. . umbrella. (_a little shade._) _fam._ semiphyllidiana, lam. patelloidea, bl.--_descr._ patelliform, sub-orbicular, compressed, rather irregular; apex slightly raised, placed near the centre; margin acute; internal surface with a central, callous, coloured disc, surrounded by a continuous, irregular muscular impression.--_obs._ this genus is known from patella, by its continuous muscular impression. it is commonly called the chinese umbrella shell. there are but two species at present known; the u. mediterranea, and the u. indica, fig. . undated. (_unda_, a wave.) waved. undulated. (_undulatus._) minutely waved. unguiculated. (_unguis_, a nail or hoof.) an unguiculated operculum is one in which the layers are disposed laterally, and the nucleus constitutes part of the outer edge. ungulina. daud. (_ungula_, a nail or claw.) _fam._ mactracea, lam. conchacea, bl.--_descr._ equivalve, sub-orbicular, sub-equilateral, with margins entire, simple, closed all round; hinge with one short, sub-divided cardinal tooth in each valve, and a very minute additional tooth in one valve, an oblong ligamentary pit divided into two portions, one of which receives the cartilage, the external ligament is immediately below the umbones; muscular impressions, two in each valve, oblong; impression of the mantle entire. u. transversa, fig. . coast of africa. uni-auriculated. having one auricle. see auriculated. unicornus. montf. monoceros, auct. unio. (_a pearl._) _fam._ nayades, lam. submytilacea, bl.--_descr._ inequilateral, equivalve, regular, free, pearly within, covered by a smooth epidermis without; umbones prominent, generally corroded; muscular impressions two in each valve, lateral, distant; the anterior composed of several small divisions; hinge varying in age, species, and individuals.--_obs._ the above description is framed so as to include all the genera of the lamarckian nayades, together with castalia, which are placed in the family trigonacea, they are all fresh-water shells, commonly called fresh-water muscles. the distinctions of the various genera into which they have been divided, will be found in their respective places, and under the name nayades. they are all represented in figures to . of these fig. to , are more generally considered as forming the genus unio. uniopsis. sw. a sub-genus of alasmodon. sw. p. . univalve. (_unus_, one; _valva_, valve.) a shell consisting of a single piece, as distinguished from bivalves and multivalves, which are composed of two or more principal pieces. spiral shells having an operculum, are called sub-bivalves by some authors. upper-valve. the free valve in attached bivalves. uvigerina. d'orb. a genus of microscopic foraminifera. vagina. megerle. solen _vagina_, auct. vaginula. (_a little sheath, the husk of corn._) _class_, pteropoda, lam.--_descr._ pyramidal, slightly inflated in the centre, thin, fragile; aperture oblong, with the edges turned slightly outwards.--_obs._ the little shells of this genus, which are only known in a fossil state, differ from cuvieria in being pointed at the extremity. found in the tertiary beds of bordeaux. v. daudinii, fig. . vaginulina. d'orb. a genus of microscopic foraminifera. valvata. müll. _fam._ peristomata, lam. cricostomata, bl.--_descr._ thin, turbinated; spire short, composed of from three to six rounded whorls; aperture circular; peritreme acute, entire; operculum horny, spiral.--_obs._ this genus of small shells resembles cyclostoma, from which the recent species may be known by the horny texture of the external surface, being fresh-water shells. the fossils of course belong to the fresh-water formations. v. piscinalis, fig. . europe and north america. valves. (_valva_, a door, a folding piece.) the two pieces composing a bivalve shell, which close upon each other, turning upon a hinge consisting of a ligament, cartilage, and teeth. see bivalve, multivalve, and univalve. valvulina. d'orb. a genus of microscopic foraminifera. varix. (_a swelling vein._) a varix is formed on the outer surface of a spiral shell, by the thickened, reflected edge of a former aperture, after fresh deposits of testaceous matter have increased the size by adding to the growth of the shell beyond it. in this manner there are frequently many varices, or edges of former apertures, in various parts of the spire and the body whorl. they are sometimes placed at regular distances from each other, as in harpa, fig. ; sometimes _continuous_, as in ranella, fig. ; sometimes _discontinuous_, as in triton, fig. ; sometimes _ramose_, as in murex, fig. ; sometimes _simple_, as in scalaria, fig. ; sometimes _spinose_, as in murex spinosus. the term _varix_ has also been applied to any swelling ridge, such as that on the lower part of the columella of ancillaria, fig. . velates. montf. neritina perversa, auct. fig. . velletia. gray? a genus described as differing from ancylus in being dextral. velletia lacustris, ancylus lacustris, auct. fig. sowerby gen. fig. . velutina. auct. _fam._ macrostomata, lam.--_descr._ sub-globose, covered with a velvety epidermis; spire short, composed of two rapidly enlarged ventricose whorls; aperture large, sub-ovate; peritreme thin, entire, separated from the last whorl; columella tortuous, thin.--_obs._ this shell does not resemble any other genus in the family. fig. . northern seas. venericardia. lam. a genus composed of the shorter species of cardita. venerirupis. lam. (from _venus_ and _rupis_, a rock.) the oblong species of venus auct. which live in cavities of rocks and stones. this genus is united by sowerby with some other species of venus under the name pullastra. v. vulgaris, fig. . ventral. (_venter_, the belly.) the margin of a bivalve shell opposite the hinge. the under valve in brachiopodous bivalves is the ventral valve. the ventral surface of an univalve spiral shell is that which faces the observer when the aperture is placed towards him. the ventral part of the whorls of symmetrical convolute shells, is the inner part, that which is nearest to the spire. ventral siphon. in symmetrical convolute univalves, is one placed near the inner edge of the whorls. ventricose. (_ventricosus._) swelled, rounded out, (_bombé fr._) as harpa ventricosa, fig. . venus. auct. (_goddess of beauty._) _fam._ marine conchacea, lam. conchacea, bl.--_descr._ equivalve, inequilateral, sub-globose, sub-ovate, transverse, externally rugose, striated, ribbed, cancellated or smooth; margins entire, simple, close; hinge with three more or less distinct cardinal teeth, diverging from the umbones in each valve; muscular impressions two, lateral, distant; palleal impressions sinuated posteriorly; ligament external.--_obs._ this extensive genus, including some bivalves of splendour and beauty, justifying the name given to it, may be known from cytherea by the absence of a lateral tooth, which is found near the cardinal teeth in the latter. artemis is distinguished not only by its beautiful form, but by the deep angular sinus in the palleal impression. fig. , a. found mostly in temperate and tropical climates. vermetus. adanson. _fam._ scalariana, lam. cricostomata, bl.--_descr._ spiral at the apex, irregularly twisted towards the aperture; aperture round, small.--_obs._ this shell resembles the serpulæ in general appearance, although it is regularly spiral near the apex. the animal is known to be a true mollusc, rather nearly allied to that of the genus dentalium, which is also placed wrongly in the lamarckian system. vermetus lumbricalis, fig. . coast of africa. vermicular. (_vermicularis._) worm-shaped, tubular, serpentine. _ex._ vermilia triquetra, fig. . vermicularia. lam. vermetus, adanson; afterwards vermetus, lam. vermilia. lam. a genus composed of species of serpula, which are attached by the whole length of the shell, no part being free. vermilia triquetra, fig. . vertebralina. d'orb. a genus of microscopic foraminifera. vertex. apex. vertigo. müll. _fam._ colimacea, lam.--_descr._ cylindrically fusiform, sinistral, hyaline; aperture marginated, sinuated, denticulated on the inner edge; peristome sub-reflected.--_obs._ this genus of minute land shells, resembles pupa, but is a reversed, hyaline shell. vertigo pusilla, fig. . europe. verruca. schum. clitia, leach. vesica. sw. a sub-genus of bulinus, sw. p. . vexilla. sw. a genus of "nassinæ," sw. thus described: "general shape of _purpura_, the inner lip flattened and depressed; the outer, when adult, thickened, inflected and toothed; aperture wide; picta _sw._ chem. pl. , f. - ." sw. malac. p. . virgulina. d'orb. a genus of microscopic foraminifera. vitrella. sw. a sub-genus of "bullinæ," sw. lardn. cyclop. malac. p. . vitrina. drap. (_vitreus_, glassy.) _fam._ limacinea, lam. and bl.--_descr._ ovate, thin, glassy, fragile; spire short; last whorl large; aperture wide, transverse; peritreme simple; columella spiral, linear.--_obs._ this genus of land-shells is not known in a fossil state. the recent species are found among moss and grass, in shady situations. de ferussac has divided this genus into helicolimax, fig. , and helixarion, fig. . vitularia. sw. a genus of "muricinæ," sw. thus described: "general habit of _muricidea_, but the inner lip is depressed and flattened as in the _purpurinæ_; varices simple, nearly obsolete. tuberculata, sw. en. m. . fig. . (_murex vitulinus_, auct.)" sw. p. . vivipara. a generic name given by montfort, and retained by some authors for paludina, lam. on account of the animals being _viviparous_, i. e. the young being perfectly formed before they leave the ovaries. viviparous. see vivipara. voluta. auct. (_volvo_, to revolve.) _fam._ columellaria, lam. angyostomata, bl.--_descr._ sub-ovate, rather angulated, thick, generally tuberculated, smooth; spire short, conical, with a mammillated apex; aperture generally angulated, large, terminating anteriorly in a deep notch; columella smooth, with several plaits, of which the lowest is the largest; outer lip thickened within.--_obs._ the genus voluta, as left by linnæus, is only characterized by the folds on the columella, and includes many shells which, although they agree in this respect with the genus, are yet quite opposite to each other in all other characters. thus the auriculæ, which are land shells, and have the aperture entire, are mixed up with others which are marine, and have a canal, as turbinellæ, and the fasciolariæ, and others which have merely a notch, as the true volutes. this genus, as it is circumscribed at present, includes a great number of beautiful shells, most of which are rich in colouring. cymba and melo have been separated by mr. broderip from the genus voluta of lamarck, for reasons stated in their respective descriptions. fig. . volvaria. lam. (_volva_, a shuttle.) _fam._ columellaria, lam.--_descr._ cylindrical, convolute, spirally striated; spire very short, nearly hidden; aperture narrow, as long as the whole shell; columella with three oblique plaits; outer lip dentated.--_obs._ the volvaria are only known in a fossil state, and resemble some species of bulla in general form, but are distinguished by the plaits on the columella. fig. , v. concinna. volutella. sw. (_a little volute._) a genus composed of those species of marginella, auct. which have the spire concealed, and the aperture smooth within. fig. , persicula of schumacher. volutilithes. sw. (_voluta_, and [greek: lithos], _lithos_, a stone.) a genus composed of some fossil species of voluta, which have the plaits on the pillar generally numerous, indistinct, and sometimes wanting altogether, with a pointed spire. fig. , v. spinosa. volution. see whorl. vorticialis. lam. a genus of microscopic foraminifera. vulsella. lam. (_a little tongue._) _fam._ ostracea, lau. margaritacea, bl.--_descr._ equivalve, irregular, longitudinal, compressed, oblong; umbones separated by a slight area in both valves; hinge with a large pit in the centre, containing the cartilage, the ligament being spread over the areas; muscular impressions, one on each valve, sub-central, oblong.--_obs._ this genus differs from ostræa in the equality of the valves, and in having a hollow pit in the hinge for the cartilage. vulsella lingulata, fig. . watering-pot. aspergillum, fig. , commonly so called on account of the resemblance of its perforated termination to that of the spout of a watering-pot. wentle trap. scalaria pretiosa, commonly so called. whorl. a complete turn or revolution round the imaginary axis of a spiral shell. the last whorl is called the _body-whorl_. the whorls are described as _non-contiguous_, when they do not touch each other; _continuous_, in the opposite case. _depressed_ when they are flat. they are _angulated_, _heeled_, or coronated; _distinct_, or indistinct. they are sometimes, as in cypræa, hidden by the last whorl. xylophaga. sow. ([greek: xulon], _zylon_, wood; [greek: phagô], _phago_, to eat.) _fam._ tubiscolæ, lam.--_descr._ equivalve, globose, closed at the back; with a large, angular hiatus in front; hinge with a small curved tooth advancing from beneath the umbones in each valve.--_obs._ this shell, which is found in a cylindrical cavity, eaten in wood by the animal, resembles teredo, but has not the shelly tube, nor the posterior hiatus. x. dorsalis, fig. , . xylotrya. leach. xylophaga, sow. zonites. montf. a genus formed of helix algira, and other similar species with depressed spires and large umbilici; included in the sub-genus helicella. fig. . zua. leach. a genus described as differing from bulinus in having a polished epidermis, and a thickened, not reflected lip. zua lubrica, b. lubricus, auct. zurama. leach. a sub-genus of helix. h. pulchella, auct. gray's turton, p. . * * * * * explanation of plates, and systematic view of the lamarckian arrangement. _class_, annelides. _order_, sedentaria. _fam._ dorsalia. fig. . siliquaria anguina. agathirses, montf. _fam._ maldania. . dentalium octogonum. . pharetrium fragile, with the outer tube broken. _fam._ serpulacea. . serpula bicarinata. . spirorbis nautiloides, on sea-weed. . galeolaria decumbens, on a conia. . vermilia triquetra. . spiroglyphus, on a portion of patella. . magilus antiquus, old shell. campulotus, guild. (from guerin.) . the same, in a young state. . leptoconchus striatus. . stylifer astericola. . the same, in a portion of star-fish. _class_, cirripedes. _order_, sessile cirripedes . tubicinella balænarum. . coronula testudinaria. chelonobia, leach, astrolepas, klein. . ---- balænaris. cetopirus, ranz. . ---- diadema. diadema, ranz. . chthalamus, ranz. (from blainville.) . platylepas pulchra, leach. one valve separate, showing the inside. . clitia verruca, leach. octhosia, ranz. verruca, schum. . conia porosa. teraclita, schum. . elminius leachii. . catophragmus imbricatus, (from sowerby's genera.) . octomeris angulosus, (from sow. gen.) . balanus tintinnabulum. . ---- montagui. acasta, leach. . ---- galeatus, conoplæa, say. . creusia gregaria. _b._ showing the internal structure. . nobia grandis. . savignium crenatum. } } . pyrgoma cancellata. } pyrgoma, auct. } . adna anglicum. } } . megatrema semicostata.} _order_, pedunculated cirripedes. . pentelasmis lævis. antifa, lam. a. anterior. . scalpellum vulgare. . smilium peronii. . pollicipes polymeus. ramphidoma, schum. *. pollicipes mitellus. capitulum, klein. . brismæus rhophodius. . lithotrya dorsalis. absia, leach, litholepas, bl. . ibla cuvieriana. . heptalasmis warwickii. octolasmis, gray. . cineras vittatus. . otion cuvieri. _class_, conchifera. _order_, c. dimyaria. _fam._ tubicolaria. . aspergillum vaginiferum. penicillus, brug. . clavagella, a fossil species. . teredina personata. . lignite, pierced by teredinæ. . teredo navalis; _a_, tube (from sowerby's genera.) . wood bored by teredo. . xylophaga dorsalis. xylotrya, leach. . the same, in wood. (this would be more properly placed in pholadaria.) . gastrochæna modiolina, in the tube (from sowerby's genera.) . fistulana clava. } } (from sowerby's genera.) . tube of the same. } _fam._ pholadaria. . pholas dactylus; _a_, plates of the hinge. . ---- papyracea. pholadidæa. . pholadomya candida. . galeomma turtoni. . front view of the same. (here xylophaga should be placed, see tubicolaria.) _fam._ solenacea. . solen ensis. ensis, schum. ensatella, sw. . solen radiatus. solenocurtus, bl. leguminaria, schum. siliqua, megerle. . lepton squamosum. (from turton.) . novaculina gangetica. . glanconome chinensis. . panopæa australis. } } (from sowerby's genera.) . hinge of panopæa faujasii.} . glycimeris siliqua. . solenimya mediterranea. _fam._ myaria. . anatina rostrata. auriscalpium, megerle. . anatinella sibbaldii. . mya truncata. . periploma inæquivalvis. osteodesma, desh. _a_, bone of the hinge, (from blainville.) . myochama anomioides; lower valve with clavicle, and hinge of upper valve. . external view of the same, attached to a trigonia. . cleidothærus chamoides, attached valve. . upper valve of the same, with the clavicle. _fam._ mactracea. . lutraria papyracea. ligula, leach. carinella, adans. . ---- solenoides. cutellus ----? . mactra stultorum. . ---- plicataria. spisula? gray. . ---- spengleri. schizodesma, gray. . ---- bicolor. mulinia, gray. . gnathodon cuneatus. clathodon, conrad. . crassatella rostrata. . amphidesma reticulatum. . erycina plebeja. mesodesma, desh. . cuming mutica. . ungulina transversa, (from sowerby's genera.) _fam._ corbulacea. . corbula nucleus. . pandora rostrata. _fam._ lithophagidæ. . petricola roccellaria. . ---- carditoidea. coralliophaga, bl. . thracia corbuloides. . saxicava rugosa. . hiatella biaperta. . sphænia binghamii. . venerirupis vulgaris. _fam._ nymphacea. . sanguinolaria rosea. lobaria, schum. . ---- diphos. soletellina, bl. . psammobia ferroensis. gari, schum. . corbis fimbriata. fimbria, megerle. . grateloupia moulinsii. (from lea.) . egeria triangulata, (from lea.) . lucina tigerina. . tellina radiata. . ---- lingua-felis; _a_, showing the fold in the ventral margin. . tellinides rosea. . donax cuneatus. . capsa braziliensis, young. . astarte danmoniensis. crassina, lam. fluviatile conchacea. . cyclas rivicola. cornea, megerle. . pisidium amnicum. pisum, megerle. . cyrena fuscata. corbicula, megerle. . cyrenoides dupontia. . potamophila radiata. galathæa, lam. _v._ ventral margin. marine conchacea. . cyprina vulgaris. arctica, schum. . cythera meretrix; _e._ escutcheon. _a._ c. meroe; _gen._ meroe. _b._ c. tripla; _gen._ trigona. _c._ c. maculata; _gen._ chione. _d._ c. castrensis; _gen._ circe. . artemis lincta; _s_, sinus in the palleal impression. . venus cancellata. antigona, schum. _a._ anterior; _p._ posterior; _c._ cardinal teeth. _a._ v. verrucosa. dosina, schum. . pullastra textile. _fam._ cardiacea. . venericardia, recent species, resembling v. planicostata, lam. . cardium dionæum. cardissa, sw. hemicardium, nonnull. . ---- angulatum. *. ---- greenlandicum. aphrodita, lea, acardo, sw. **. --- hemicardium. _gen._ hemicardum. . cardita calyculata. . cypricardia angulata. . isocardia moltkiana. . megalodon cucullatus, (from sow. min. con.) . hippagus isocardioides, (from lea.) . hippopodium ponderosum, (from sow. min. con.) . pachymya gigas, (from sow. min. con.) _fam._ arcacea. . arca antiquata. . bysso-arca noæ. . cucullæa auriculifera, (from sowerby's genera.) . pectunculus pilosus. . myopara costata, (from lea.) . crenella. . nucula margaritacea, three views. . solenella norrissii. _fam._ trigonacea. . trigonia pectinata. . castalia ambigua. tetraplodon pectinatus, spix. _fam._ nayades. . alasmodon complanatus, say. margaritana, schum. . dipsas plicatus, leach. cristaria, schum. . hyria corrugata, lam. paxyodon, schum. triplodon. . syrmatophora, sow. prisodon, schum. diplodon, spix. . unio littoralis, lam. mysca ovata, turton. . ---- alatus. symphynota, lea. . ---- atratus, lam. naia, sw. . monocondylæa paraguayana. . iridina elongata. pleiodon, conrad. } platiris, lea. } . mycetopus solenoides, d'orb. spatha, lea. } . anodon cataractus. _fam._ chamacea. . chama lazarus. jataronus, adanson. . diceras perversum, (from sowerby's genera.) . etheria semilunata. _order_, monomyaria. _fam._ tridacnacea. . hippopus maculatus. . tridacna elongata. _fam._ mytilacea. . mytilus achatinus. . ---- polymorphus. dreissina. . modiola tulipa. . lithodomus dactylus. . pinna saccata. _fam._ malleacea. . avicula hirundo. . ---- margaritifera. meleagrina, lam. . malleus vulgaris. himantopoda, schum. . perna ephippium. . catillus lamarckii. inoceramus, sow. (from blainville.) . crenatula mytoloides. } } . gervillia aviculoides. } (from sowerby's genera.) } . pulvinites adansonii. } _fam._ pectinides. . pecten varius. janera, schum. . ---- plica. decadopecten, rüppell. . hinnites pusio. pecten pusio, lam. . lima squamosa. . dianchora striata, (from sow. min. con.) . plagiostoma spinosum, (from sow. min. con.) . spondylus americanus, hinge. (see frontispiece.) . plicatula gibbosa. harpax, parkinson. . pedum spondyloideum, (from sow. gen.) _fam._ ostracea. . ostrea edulis. . ---- folium. dendostrea, sw. . gryphæa incurva. . exogyra conica, (from sow. min. con.) . placuna placenta. _gen._ placenta, schum. . vulsella lingulata. . anomia ephippium. . hinge of the same, with bony process. . hinge, showing the fissure. . placunanomia cumingii. . hinge of the same, showing the fissure. . hinge of the unattached valve. . mulleria. (from sow. gen.) _fam._ rudistis. . sphærulites foliacea. (radiolites is more conical.) . calceola sandalina. . birostrites inæquiloba, internal cast of sphærulites. . _a._ crania personata, dorsal valve; _b._ c. antiquata, interior. (this would be more properly placed in brachiopoda.) . hippurites cornucopia, (from blainville.) . hipponyx cornucopia, attached valve. . upper valve of the same. _fam._ brachiopoda. . orbicula lævis. . terebratula psittacea; _a._ anterior margin. . atrypa reticularis. trigonotreta, könig. . cyrtia exporrecta. . delthyris plycotes, (from dalman.) . leptæna depressa, dalman. producta, sow. (from sow. gen.) *. producta antiquata. . orthis basalis, dalman. strophomena, rafinesque. . trigonosemus lyra, könig. . magas pumilus, sow. . gypidia conchidium, (from dalman.) . interior of the large valve of the same. (from dalman.) . pentamerus aylesfordii, (from sow. min. con.) . ---- lævis. . spirifer trigonalis. } } trigonotreta, könig, (from sow. gen.) . ---- dorsatus. } . thecidium recurvirostrum. (here should come crania, see rudistes.) . pycnodonta radiata, (from fischer.) . hinge of the same. . lingula anatina. _class_, mollusca. _order_, pteropoda. . atlanta helicialis. . cleodora cuspidata. . creseis spinifera. . cuvieria columella. . spiratella limacinea, with animal; limacella, lam. limacina cuvier. (from blainville.) . vaginula daudinii. . hyalæa tridentata. archonte, montf. _order_, gasteropoda. _fam._ phyllidiana. . chiton spinosus. . chitonellus striatus. (from sow. gen.) . patella oculus; _a._ anterior. . patella pellucida. helcion, montf. ansates, klein. . patelloida antillarum. lottia, gray. *. siphonaria sipho. _fam._ semiphyllidiana. . pleurobranchus membranaceus. . umbrella indica. gastroplax, bl. _fam._ calyptracea. . calyptræe equestris. . ---- extinctorium. . ---- auriculata. . ---- pileus. infundibulum, montf. . side view of the same. . crepidula porcellana. . capulus ungaricus, two views. pileopsis, lam. . emarginula fissura. . parmophorus elongatus. scutus, montf. . rimula blainvillii. . cemoria flemingii. . fissurella oriens. . ancylus fluviatilis. _fam._ bullæana. . bulla fragilis. akera, nonnul. . ---- aperta. bullæa, lam. . ---- aplustre. aplustre, schum. . ---- naucum. atys, montf. . ---- lignaria. scaphander, montf. . ---- ampulla. . ---- lineata. _fam._ aplysiacea. . aplysia petersoni. . dolabella rumphii. _fam._ limacinea. . parmacella calyculata, cryptella. webb. . parmacella olivieri. (from de ferussac.) . ---- palliolum. (from de ferussac.) . limax antiquorum. . plectophorus corninus. . testacella haliotoidea. . helixarion, cuv. } } vitrina, drap. cobresia, haubner. . helicolimax pellucida. } _order_, trachelipoda. _fam._ colimacea. _sub-genera_ of de fer. . helix brevipes, drap. helicophanta. . succinea amphibia. } } cochlohydra. . ---- patula. amphibulima, lam. } . helix hæmastoma. acarus, } montf. } . ---- pomatia. } helicogena. } . streptaxis contusa, gray.} } . another view of the same.} . anastoma depressum. } } . another view of the same. } } . helix nux-denticulata. } helicodonta. } . proserpina nitida. } } . polygyra septemvolva. } } . another view of the same. } . carocolla lamarckii. } } helicigona. . helix pileus. geotrochus, sw. } . ---- algira. zonites, montf. } } helicella. . ---- citrina. naninia, gray. } . ---- epistilum helicostyla. . bulinus rosaceus; _a._ apex. } } . ---- guadaloupensis; bulinulus, } leach. } cochlostyla. . ---- lyonetianus. gibbus, montf. } } . ---- lubricus. cionella, jeffreys.} . achatina virginea liguus, montf. } } cochlitoma. . achatinella, sw. } . polyphemus glans, montf. cochlicopa. . bulinus decollatus, in a young state. cochlicella. . azeca tridens, jeffreys. turbo tridens, } cochlogena. gmelin. } . pupa uva. } } . alæa marginata; jeffreys. } } cochlodonta. . vertigo pusilla. } } . megaspira ruschenbergiana. } . clausilia macascarensis; _a_, a break, } to show the clausium. } cochlodina. } . balea fragilis. } . auricula judæ. . ---- coniformis. conovulum, lam. melampus, montf. . pedipes adansonii. *. scarabæus imbrium. . chilina dombeyana. . carychium minimum. . partula australis. . cyclostoma ferrugineum. . ---- involvulus. cyclophorus, montf. . nematura deltæ. . helicina major. . operculum of the same. _fam._ lymneana. . limnæa stagnalis. . ---- auricularia. radix, montf. . ---- castanea. physa, drap. . planorbis corneus. . planaria niteus, (from lea.) _fam._ melaniana. . melania subulata. melas, montf. . melania prærosa and monodontoides. anculosa, say. . melanopsis costata. faunus, montf. . pirena terebralis. . pasithæa striata, (from lea.) _fam._ peristomata. . ampullaria fasciata. amphibola; _a_, aperture. . ---- guinaica. lanistes, montf. . ---- cornu-arietis. ceradotes, guild. . paludina bengalensis. . valvata piscinalis. _fam._ neritacea. . navicella elliptica. . neritina virginea. theodoxus, montf. . ---- spinosa. clithon, montf. . ---- perversa. velates, montf. (from sow. gen.) . natica mamilla. polinices, montf. . ---- lineata. . nerita peloronta. peloronta, oken. . neritopsis granosa. . pileolus plicatus. . janthina fragilis. _fam._ macrostomata. . sigaretus concavus. . stomatia phymotis. . stomatella imbricata. . velutina lævigata. galericulus, nonnul. . haliotis rubra, young. . ---- tricostalis, lam. padollus, montf. . scissurella elatior, magnified. } } (from sow. gen.) . pleurotomaria reticulata. } _fam._ plicacea. . pyramidella terebellum. . tornatella solidula. acteon, montf. . monoptygma elegans. (from lea.) _fam._ scalariana. . vermetus lumbricalis. . rissoa reticulata. . eulima labiosa. . ---- marmorata. bonellia, desh. . cirrus nodosus, sow. . euomphalus pentangulus. (from sow. min. con.) . scalaria pallassii. aciona, leach. . delphinula laciniata. _fam._ turbinacea. . solarium perspectivum. . ---- bifrons. bifrontia and omalaxis, desh. . orbis rotella. (from lea.) . another view of the same. . rotella vestiaria, pitonellus, montf. . trochus stellaris, lam. calcar, montf. turbo, sow. . ---- maculatus. tectus, montf. . ---- agglutinans. phorus. . ---- pharaonis. clauculus, montf. . margarita tæniata. . littorina vulgaris. *. assiminea grayana. . lacuna pallidula. . planaxis sulcata. . monodonta labeo; odontis, sow. . phasianella variegata. . turbo setosus. marmarostoma, sw. . tuba striata. (from lea.) . turritella imbricata. . monotygma, gray. _fam._ canalifera. . cerithium aluco, front. . nerinea goodhallii. (from geol. trans.) . triphora plicata. (from deshayes.) . end view of the same. . potamis muricata. pyrazus, montf. tympanostomata, schum. . cerithium telescopium. _gen._ telescopium. . pleurotoma babylonia; _a, a_, extremities of the axis. . ---- strombiformis, clavatula, lam. . turbinella corniger. scolymis, sw. . ---- polygona. polygonum, schum. . spirillus. _gen._ pyrella, sw. turbinella spirillus, auct. . cancellaria reticulata. . fasciolaria trapezium. . fusus colus; _a_, anterior of the aperture; p, posterior. . pyrula perversa. fulgur, montf. . ---- papyracea. rapanus, schum. bulbus, humph. rapella, sw. . ---- ficus. ficula, sw. . struthiolaria straminea. . ranella ranina. apollon, montf. . ---- neglecta. bufo, montf. . murex inflatus. chicoreus, montf. . ---- haustellum. brontes, montf. . typhis tubifer. (from deshayes.) . triton pilearis. . ---- cutaceus. aquillus, montf. . ---- lotorium. lotorium, montf. . ---- anus. persona, montf. _fam._ alatæ. . rostellaria curvirostrum. . ---- columbaria. hippochrenes, montf. (from sow. gen.) . ---- pes-pelicani. aporrhais, petiver. . pteroceras aurantiacum. . strombus pugilis. _fam._ purpurifera. . cassidaria echinophora. morio, montf. . side view of the outer lip, to shew the canal. . oniscia oniscus. cassidara. . cassis tuberosa, reduced. . ---- erinaceus. cassidea, sw. . ---- testiculus. cypræcassis, stutchbury. . ricinula horrida. sistrum, montf. . purpura persica. . tritonidea (_pollia_, gray.) articularis. . phos senticosa. . monoceros crassilabrum. . concholepas peruviana. . harpa ventricosa. . dolium maculatum. . buccinum undatum; _a_, anterior of the aperture; _p_, posterior. . ---- papillosum. alectrion, montf. . nassa arcularia. . ---- neritoidea. cyclops, montf. . cyllene, gray. . eburna zeylanica. . bullia vittata. . terebra maculata. subula, bl. . trichotropis bicarinata. _fam._ columellata. . columbella mercatoria. . mitra plicaria; _c_, termination of the columella. . conohelix marmorata. . voluta vespertilio. cymbiola, sw. . cymba porcina. . melo Æthiopicus. . volutilithes spinosus. . marginella glabella. glabella, sw. cucumis, klein. . ---- persicula. volutella, sw. persicula, schum. . volvaria concinna. _fam._ convolutæ. . ovulum ovum. . ---- verrucosum. calpurnus, montf. . ---- volva. radius, montf. . ---- gibbosum. ultimus, montf. . cypræovulum capense. . cypræa arabica, back. . the same, front. . cypræa algoensis. luponia, gray, front. . ---- pediculus. trivia, gray, back. . the same, front. . terebellum convolutum. seraphs, montf. . ---- subulatum, front. . erato mangeriæ. . ancillaria glabrata. anolax, brongn. . ---- cinnamonea. . oliva maura. . ---- subulata. hiatula, sw. . conus nocturnus. rhombus, montf. . ---- nussatella. hermes, montf. . ---- textile. cylinder, montf. . ---- geographus. rollus, montf. _order._ cephalopoda. _first division._ polythalamous cephalopoda. _fam._ orthocerata. . amplexus coralloides. (from sow. min. con.) . orthoceratites annulatus. . nodosaria æqualis. . belemnites, with the outer coat broken to shew the alveole. . ---- portion of the alveole separated. . ---- hastatus. hibolithes, montf. (from blainville.) . conularia quadrisulcata. . conilites pyramidatus, (from blainville.) _fam._ lituacea. . spirula peronii. _fam._ nautilacea. . nummulites buticularis, outside. helicites, bl. camerina, brookes. . the same inside, to shew the chambers. . nautilus pompilius, young. see frontispiece. . simplegas sulcata. . endosiphonites. (from camb. philos. trans.) _fam._ ammonacea. . ammonoceras. (from blainville.) . ammonites; _a_, break in the shell, showing the sinuous septa. . orbulites crassus. globulites, nonnul. angulites, montf. reduced. *. ---- discus. aganides, montf. . goniatites striatus. . scaphites æqualis. . crioceratites duvallii. . turrilites tuberculatus. . baculites faujasii. portion near the centre. *. hamites cylindricus; _a_, internal cast of part of the shell; _b_, hollow external cast of the remainder. _second division._ monothalamous cephalopoda. . argonauta argo. . bellerophon tenuifasciata. (from sow. gen.) . the same, shewing the dorsal keel. _order._ heteropoda. . carinaria mediterranea. * * * * * explanation of the new plates. _order._ sessile cirripedes. . pyrgoma monticularia. _sub-genus_, daracia, gray, back and front. . the same, in situ. _fam._ myaria. . lyonsia norvegica. anatina, nonnul. inside view of both valves. . outside, with the valves closed. . næra longirostrum. anatina longirostris, lam. inside of both valves. . outside, with both valves closed. . a smaller species of næra, shewing the inequality of the valves. _fam._ mactracea. . amphidesma tennis. abra, leach. . ervillia nitens. _fam._ corbulacea. . potamomya, of some authors. a fresh-water shell resembling corbula. outside, valves closed. . inside of both valves. fluviatile conchacea. . cyclas amnica. pera, leach. _fam._ cardiacea. . cardilia semisulcata. isocardia semisulcata, lam. internal view. . external view of the same valve. . cardium apertum. papyridea, sw. . the same, shewing the umbones. . pleurorynchus, fossil, (from mineral conchology.) _fam._ phyllidiana. . chiton fascicularis. phakellopleura, guild. . ---- amiculatus. amicula, gray. _fam._ calyptracea. . scutella, brod. internal view. . external view of the same. . ancylus, a reversed species, illustrating the genus velletia, gray. enlarged view. . the same, natural size. . pedicularia. enlarged figure, (copied from swainson.) . the same, natural size, growing on coral. _fam._ colimacea. . achatina? octona. macrospira, guild. . stenopus cruentatus, guild. under side. . ---- lividus. . helix, the aperture covered by the epiphragm. . pupa secale, drap. abida, leach. . ---- pagoda. gonidomus, sw. . truncatella, enlarged figure. . the same, natural size. . auricula caprella. _gen._ caprella, nonnul. front view. . the same, dorsal view. . pupina vitrea. . ---- antiquata. . ---- namezii. . ---- lubrica. callia? gray. . cyclostoma, a pupiform species. megalomastoma, guild. . ---- planorbulum. cyclotus, guild. . ---- a similar species, with the complicated notch at the posterior part of the aperture. pterocyclos, gray. . helicina acutissima, nobis. view of the under side. trochatella, sw. . the same in profile. . } } . } strophostoma, desh. three views. } . } _fam._ peristomata. . paludina impura. bithinia, gray? . ampullaria avellana. thallicera, sw. ampullarina? . a species of ampullaria having a thickened ledge on which the shelly operculum rests. pachystoma, guild. changed to pachylabra, sw. _fam._ plicacea. . ringicula, desh. a fossil species, front view. . back view of the same. _fam._ turbinacea. . turbo nicobaricus. chrysostoma, sw. . trochus iris. elenchus, humph. _fam._ purpurifera. . purpura vexilla. _gen._ vexilla, sw. . priamus. achatina priamus, auct. the propriety of placing it in this family will depend upon the correctness of the statement made by dr. beck that this shell is marine, and possesses an operculum. . purpura crispata. polytropa, sw. . pseudoliva plumbea. gastridium, sow. _fam._ canalifera. . fusus longevus. clavalithes, sw. . ---- bulbiformis. leiostoma, sw. . pyrella, sw. turbinella spirillus, auct. . pleurotoma lineata. tomella, sw. . pyrula melongena. _gen._ myristica, sw. . murex vitulinus. _gen._ vitulina, sw. . typhis sowerbii. . a brown variety of the same. . typhis cumingii. _fam._ columellata. . voluta vexillum. harpula, sw. . mitra monodonta. mitreola, sw. . ---- bicolor. mitrella, sw. . columbella nitidella. _gen._ nitidella, sw. _fam._ convolutæ. . oliva volutella. _gen._ lamprodoma, sw. . ---- maura. . cypræa globulus. _gen._ globularia, sw. . ---- pulchella, fossil. _gen._ cyprædia, sw. the end. * * * * * table of lamarck's conchological system. _classes of invertebrated _orders._ _families._ _genera._ animals._ annelides. sedentary _dorsalia_ siliquaria. _maldania_ dentalium. _serpulacea_ serpula, spirorbis, galeolaria, vermilia, magilus. cirripedes. sessile tubicinella, coronula, _multivalve._ balanus, acasta, pyrgoma, creusia. pedunculated anatifer, pollicipes, cineras, otion. conchifera dimyaria _tubicolaria_ aspergillum, clavagella, _bivalve._ fistulana, septaria, teredo, teredina. _pholadaria_ pholas, gastrochæna. _solenacea_ solen, panopæa, glycimeris. _myaria_ mya, anatina. _mactracea_ lutraria, mactra, crassatella, erycina, ungulina, solemya, amphidesma. _corbulacea_ corbula, pandora. _lithophagidæ_ saxicava, petricola, venerirupis. _nymphacea_ sanguinolaria, psammobia, psammotæa, tellina, tellinides, corbis, lucina, donax, capsa, crassina. _fluviatile cyclas, cyrena, galathæa. conchacea_ _marine conchacea_ cyprina, cytheræa, venus, venericardia. _cardiacea_ cardium, cardita, cypricardia, hiatella, isocardia. _arcacea_ cucullæa, arca, pectunculus, nucula. _trigonacea_ trigonia, castalia. _nayades_ unio, hyria, anodon, iridina. _chamacea_ diceras, chama, etheria. monomyaria _tridacnacea_ tridacna, hippopus. _mytilacea_ modiola, mytilus, pinna. _malleacea_ crenatula, perna, malleus, avicula, meleagrina. _pectenides_ pedum, lima, plagiostoma, pecten, plicatula, spondylus, podopsis. _ostracea_ gryphæa, ostræa, vulsella, placuna, anomia. _rudistes_ sphærulites, radiolites, calceola, birostrites, discina, crania. _brachiopoda_ orbicula, terebratula, lingula. mollusca pteropoda hyalæa, cleodora, limacina, _univalve._ cymbulia. gasteropoda _phyllidiana_ chiton, chitonellus, patella. _semiphyllidiana_ pleurobranchus, umbrella. _calyptracea_ parmophorus, emarginula, siphonaria, fissurella, pileopsis, calyptræa, crepidula, ancylus. _bulleana_ bulla, bullæa. _aplysiacea_ aplysia, dolabella. _limacinea_ parmacella, limax, testacella, vitrina. trachellipoda _colimacea_ helix, carocolla, anastoma, helicina, pupa, clausilia, bulinus, achatina, succinea, auricula, cyclostoma. _lymneana_ planorbis, physa, lymnæa. _melaniana_ melania, melanopsis, pirena. _peristomata_ valvata, paludina, ampullaria. _neritacea_ navicella, neritina, nerita, natica, janthina. _macrostomata_ stomatia, stomatella, haliotis. _plicacea_ tornatella, pyramidella. _scalariana_ vermetus, scalaria, delphinula. _turbinacea_ solarium, rotella, trochus, monodonta, turbo, planaxis, phasianella, turitella. _canalifera_ cerithium, pleurotoma, turbinella, cancellaria, fasciolaria, fusus, pyrula, ranella, murex, triton. _alata_ rostellaria, strombus, pteroceras. _purpurifera_ cassidaria, cassis, ricinula, purpura, monoceros, concholepas, harpa, dolium, buccinum, eburna, terebra. _columellata_ columbella, mitra, voluta, marginella, volvaria. _convoluta_ ovulum, cypræa, oliva, ancillaria, conus. polythalamous _orthocerata_ belemnites, orthoceras, cephalopoda nodosaria, hippurites, conilites. _lituacea_ spirula, spirolina, lituola. _cristacea_ renulina, cristellaria, orbiculina. _spherulacea_ miliola, gyrogona, melonia, (microscopic.) _radiolacea_ rotalites, lenticulina, placentula, (micros.) _nautilacea_ discorbites, siderolites, polystomella, vorticialis, nummilites, nautilus. _ammonacea_ ammonites, ammonoceras, turrilites, baculites. monothalamous argonauta. cephalopoda heteropoda carinaria. * * * * * table of the conchological system of de blainville. key. = type malacozoaria = sub-type malentozoaria classes a = cephalophora b = paracepholophora dioica c = paracephalophora monoica d = paracephalophora hermaphrodita e = acephalophora f = nematopoda g = polyplaxiphora orders a = cellulacea b = polyphalamacea c = siphonobranchiata d = asiphonibranchiata e = pulmobranchiata f = chismobranchiata g = monopleurobranchiata h = aporobranchiata i = nucleobranchiata j = cirrobranchiata k = cervicobranchiata l = scutibranchiata m = palliobranchiata n = rudistes o = lamellibranchiata _classes._ _families._ _genera._ _orders._ {_planulacea_ renulina, peneroplis. { { a {_sphærulacea_ {miliola, pollontes, melonia, { { {saracenaria, textularia. { { { {_nummulacea_ {nummulites, orbiculina, { {helicites, placentula, { {vorticialis, siderolites. { a { { { {_orthocerata_ {belemnites, conularia, { { { {conilites, orthoceras, { { { {baculites. { { { { { {_lituacea_ {icthysarcolites, lituola, { { { {spirula, spirolina, { { { {hamites, ammonoceras. { { { { { b {_cristacea_ crepidulina, oreas, linthuris. { { { {_ammonacea_ {discorbis, scaphites, { { {ammonites, simplegas. { { { {_nautilacea_ {polystomelle, nautilus, { { {lenticulina. { { { {_turbinacea_ cibicides, rotalia. { { { {_turriculacea_ turrilites. { { {pleurotoma, rostellaria, { {fusus, pyrula, { {_siphonostomata_ {fasciolaria, turbinella, { { {columbella, triton, { { {struthiolaria, ranella, { { {murex. { { { { {cerithium, pyrena, melanopsis, { { {planaxis, subula, terebra, { { {eburna, buccinum, harpa, { { c {_entomostomata_ {dolium, cassis, cassidaria, { { { {ricinula, cancellaria, { { { {purpura, concholepas, terebra, { { { {mitra { { { {_univalves_ { { { {strombus, conus, terebellum, { { { {_angyostomata_ {oliva, ancillaria, voluta, { { { {mitra, marginella, volvaria, { { { {cypræa, ovulum. { { { { { { {_goniostomata_ solarium, trochus. { { b { { { { { { {monodonta, turbo, { { { { {pleurotomaria, littorina, { { { { {delphinula, cyclostoma, { { { {_cricostomata_ {paludina, valvata, scalaria, { { { { {proto, turitella, vermetus, { { { { {siliquaria, magilus. { { { { { { { d {_hemicyclostomata_{nerita, neritina, clithon, { { { {velates, pileolus, navicella, { { { {natica. { { { { { {_ellipsostomata_ {helicina, ampullaria, melania, { { { {rissoa, phasianella, { { { {pleurocerus. { { { { { {_oxystomata_ janthina. { { { { {_limnacea_ limnæa, physa, planorbis. { { { { { {_auriculacea_ {auricula, pedipes, tornatella, { { c e { {tomogerus, pyramidella. { { { { { { {succinea, bulinus, achatina, { { { _limacinea_ {clausilia, pupa, partula, { { {helix, vitrina, testacella, { { {parmacella, limacella, limax. { { { { f {sigaretus, cryptostomata, { { {stomatella, velutina. { { { { {_sub-aplysiaca_ pleurobranchus. { { { { { g {_aplysiaca_ aplysia, dolabella. { { { { { {_patelloidea_ umbrella, siphonaria. { { { { { {_akera_ bulla, bellerophon, sormetus. { { { { h _thecosomata_ hyalæa, cleodora, cymbulia. { { { { {_nectopoda_ carinaria. { { i { { { {_pteropoda_ {atlanta, spiratella, { { {argonauta. { { { { { j dentalium. { { { { { { {_retifera_ patella. { { d { k { { { {_branchifera_ {fissurella, emarginula, { { {parmophorus. { { { { {_otides_ haliotis, ancylus. { { l { { {_calyptracea_ {crepidula, calyptræa, { {capulus, hipponyx, notrema. { { {lingula, terebratula, { { {strophomena, dianchora, { { m {thecidium, plagiostoma, { { {podopsis, orbicula, crania. { { { { n {sphærulites, hippurites, { { {radiolites, birostrites, { { {calceola. {_bivalves_ e { { {_ostracea_ {anomia, placuna, ostræa, { { {gryphæ. { { { {_sub-ostracea_ {spondylus, plicatula,, { { {hinnites, pecten, pedum,, { { {lima. { { { { {vulsella, malleus, avicula, { {_margaritacea_ {perna, crenatula, inoceramus, { { {catillus, pulvinites, { { {gervillia. { { { {_mytilacea_ pinna, mytilus. { { { {_arcacea_ arca, pectunculus, nucula. { { { {_sub-mytilacea_ anodon, unio, cardita. { { { {_chamacea_ {chama, diceras, etheria, { { {tridacna, hippopus, { { {isocardium, trigonia. { { { o { {cardium, donax, tellina, { {lucina, cyclas, cyprina, {_conchacea_ {mactra, erycina, crassatella, { {venerirupis, venus, { {coralliophaga, clotho, { {corbula, sphænia, ungulina. { { {pandora, anatina, thracia, { {mya, lutricola, psammocola, { {soletellina, sanguinolaria, {_pylorides_ {solenocurtus, solen, solemya, { {panopæa, glycimeris, { {saxicava, byssomya, { {rhomboides, gastrochæna, { {clavagella, aspergillum { {_adesmacea_ {pholas, teredina, teredo, {fristulana, septaria. {_lepadicea_ {gymnolepas, pentalepas, { {polylepas, litholepas. { f { { {_balanidea_ {balanus, acasta, octhosia, _multivalves_{ {conia, creusia, pyrgoma, { {chthalamis, coronula, { {chelnobia, cetopirus, { {diadema, tubicinella. { { g _seriales_ {chiton, chitonellus. [illustration: fig. to .] [illustration: fig. to .] [illustration: fig. to .] [illustration: fig. to .] [illustration: fig. to .] [illustration: fig. to and .] [illustration: fig. and to .] [illustration: fig. to .] [illustration: fig. to . next plate.] [illustration: fig. . to .] [illustration: fig. to . . cancelled.] [illustration: fig. to .] [illustration: fig. to .] [illustration: fig. to .] [illustration: fig. to .] [illustration: fig. to . . . in the next.] [illustration: fig. . . to . in the next.] [illustration: fig. . to . .] [illustration: fig. to . in the last.] [illustration: fig. to .] [illustration: fig. to .] [illustration: fig. to .] [illustration: fig. * to .] [illustration: fig. to .] [illustration: fig. to .] [illustration: fig. to .] * * * * * works on natural history, sold at reduced prices by henry g. bohn, york street, covent garden. artis's (e. t.) antediluvian phytology, illustrated by a collection of the fossil remains of plants, peculiar to the coal formations of great britain, selected for their novelty and interest, from upwards of a thousand specimens now in the possession of the author, and systematically described, with the view of facilitating the study of this important branch of geology: including remarks on the systems of _count sternberg_, _baron schlotheim_, _professor martius_, and _mons. brongniart_; also communications from professor buckland, and other eminent geologists, to. _with plates_, (published at l s) _cloth boards_, s bauer's illustrations of the genera of ferns, in which the characters of each genus are displayed in the most elaborate manner, in a series of magnified dissections and figures, highly finished in colours, after the beautiful drawings of francis bauer, esq. botanical draughtsman to her majesty; with descriptive letter-press by sir william jackson hooker, parts to , imperial vo. - to be completed in parts, price s each. beechey.--botany of captain beechey's voyage, comprising an account of the plants collected by messrs. lay and collie, and other officers of the expedition, during the voyage to the pacific and behring's strait, performed in her majesty's ship _blossom_, under the command of captain f. w. beechey, by sir william jackson hooker and g. a. w. arnott, esq. _illustrated by plates, beautifully engraved, complete in parts_, to. _price s each._ - ---- zoology of captain beechey's voyage, compiled from the collections and notes of captain beechey and the scientific gentlemen who accompanied the expedition, by dr. richardson, n. a. vigors, esq., g. t. lay, esq., e. t. bennett, esq., richard owen, esq., john edward gray, esq., w. sowerby, esq. and the rev. dr. buckland, to. _illustrated by finely coloured plates by sowerby, extra cloth bds._ l s boase's (dr. h. s. _sec. roy. geol. soc. of cornwall_) treatise on primary geology, being an examination, both practical and theoretical, of the older formations, vo. _cuts_, (published at s) _cloth bds._ s "an admirable work, involving some of the most refined discussions of which geology is susceptible."--_literary gazette._ burmeister's manual of entomology, translated from the last german edition by w. e. shuckard, member of the entomological society, &c. with considerable and important additions by the author, (communicated expressly for this edition,) and many original notes by the translator. illustrated by thirty-three engravings on steel, in which are represented above five hundred subjects, _chiefly generic distinctions, anatomical sections, organs, eggs, larvæ, &c. of insects; together with a beautifully coloured frontispiece_, thick vol. vo. _comprising above closely printed pages_, (published at l s _in bds._) _hf. bd. morocco_, s curtis's flora londinensis; revised and improved by george graves, extended and continued by sir w. jackson hooker; comprising the history of plants indigenous to great britain, their uses, economy, and various interesting particulars, with alphabetical, linnæan, and other indexes; the drawings made by sydenham edwards and lindley, vols. royal folio (or parts), containing plates, _exhibiting the full natural size of each plant, with magnified dissections of the parts of fructification, &c. all beautifully coloured_, (pub. at l s in parts) l s ---- the same, _elegantly hf. bd. morocco, top edges gilt_, l this is the only extensive work on the indigenous botany of this country, which gives well-coloured representations of the plants _in their full natural size_. cuvier.--histoire naturelle des mammiferes, avec des figures originales enluminées, dessinées d'après les animaux vivants, ouvrage publié sous l'autorité de l'administration du muséum d'histoire naturelle, par f. cuvier et e. geoffroy saint-hilaire, vols. royal folio, _containing exquisitely coloured plates of animals_, (published at l s) _very splendidly half-bd. turkey morocco, gilt edges_, l *** the advertiser having purchased of the parisian publishers all the remaining copies of this magnificent work, is enabled to offer them at the above extremely reduced price. this is the finest work on mammiferous animals ever published in any country, and has always been considered, both for the high talent displayed in the text and the extremely beautiful execution of the plates, which resemble drawings, as taking the first place in the class to which it belongs. as very few copies remain for sale, and the price is so extremely low, the book must soon become scarce, and rise in value. "un des ouvrages les plus exacts et les mieux exécutés que l'on ait encore donnés sur les mammifères."--_brunet._ "it is unnecessary to dilate upon the splendid style in which this work is brought out, or on the ability and fidelity that characterise as well the figures as the descriptions contained in it, since these must be well known to all who have seen any of the numbers. it will doubtless form the standard work of reference for the mammalia. necessarily too expensive for general circulation, public libraries, and the collections of the rich can alone possess it; but to these it is indispensable; while the manner in which it is executed renders it worthy of a place by the side of their most costly and elegant volumes."--_zoological journal._ denny's monographia pselaphidarum et scydmÆnidarum britanniÆ; or an essay on the british species of the genera pselaphus of herbst, and scydmænus of latreille, in which those genera are subdivided, and all the species hitherto discovered in great britain are accurately described and arranged, with an indication of the situations in which they are usually found, vo. _with coloured plates, containing figures of beetles_, (pub. at l s) _extra cloth bds_. s norwich, this volume has for some time been considered scarce, and sold for more than the published price. donovan's natural history of the insects of india, new edition, considerably enlarged, brought down to the present state of the science, with alphabetical and systematic indices, etc. by j. o. westwood, esq. f.l.s. to. _with plates, containing upwards of exquisitely coloured figures_, (published at l s) _extra cloth bds. elegantly gilt_, l s ---- natural history of the insects of china, new edition, considerably enlarged, brought down to the present state of the science, with alphabetical and systematic indices, etc. by j. o. westwood, esq. f.l.s. to. _with plates, containing upwards of exquisitely coloured figures_, (published at l s) _extra cloth bds. elegantly gilt_, l s "donovan's works on the insects of india and china, are splendidly illustrated and extremely useful,"--_naturalist._ "the entomological plates of our countryman donovan, are highly coloured, elegant, and useful, especially those contained in his quarto volumes (insects of india and china) where a great number of species are delineated for the first time."--_swainson._ drury's illustrations of foreign entomology, wherein are exhibited upwards of six hundred exotic insects, of the east and west indies, china, new holland, north and south america, germany, &c. very few of which are figured in any other work; engraved with the greatest accuracy by the celebrated moses harris, author of the _aurelian_, &c. all most correctly and beautifully coloured from the original specimens, new and much improved edition, with the following important additions:--the modern names, generic and specific characters, synonymes of later naturalists; accounts of the economy, habitations, and food of many of the insects; and scientific and alphabetic indexes, by j. o. westwood, esq. f.l.s. secretary of the entomological society, &c. vols. to. _ plates_, (originally published at l s) _hf. bd. morocco, uncut_, l s d ---- the same, _richly bound in green morocco, gilt edges_, l s "the exquisite work of drury displays the complete insect in a degree of perfection that leaves nothing to be desired."--_sir james e. smith._ this new edition is exquisitely coloured, and must rank high among the luxurious publications of the age. its literary and scientific excellence is in keeping with its attractive appearance. "a few years ago, a new edition, with impressions from the original plates, was published under the editorial care of mr. westwood, by mr. henry bohn the bookseller. it is not easy to speak of this edition in terms of too high commendation. the colouring, executed from the original drawings, under the superintendence of one of the ablest entomological artists of the day, is faithful to nature, and owing to the fineness of the paper and a particular process to which it has been subjected, possesses a lustre and beauty which were unattainable at the time when the original edition appeared. the text has been in a great measure re-written; ample and accurate descriptions introduced; the modern nomenclature applied, and the intricacies of synonomy unravelled; indexes and much original matter added, and the whole work adapted to the present advanced state of the science."--_sir w. jardine._ edwards's (george) natural history of birds, new edition, vols. royal to. with plates, beautifully coloured like drawings, (published at l) _hf. bd. morocco, uncut, top edges gilt_, l s - ---- the same, large paper, with the plates beautifully coloured like drawings, vols. folio, (published at l) _hf. bd. morocco, uncut, gilt tops, rare_, l greville's cryptogamic flora, comprising the principal species found in great britain, inclusive of all the new species recently discovered in scotland, vols. royal vo. _with beautifully coloured plates_, (published at l s) _neatly half bound morocco_, l s - this, though a complete work in itself, forms an almost indispensable supplement to the thirty-six volumes of sowerby's english botany, which does not comprehend cryptogameous plants. it is one of the most scientific and best executed works on indigenous botany ever produced in this country. 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"this is a very excellent and valuable work, as indeed the talent employed on it sufficiently ensures. the plates are beautifully coloured, and the letter-press accurately and well written. we strongly recommend it to our scientific readers."--_neville wood._ lamarck's conchology, containing a complete translation of his descriptions of both the recent and fossil genera, illustrated by highly-finished lithographic plates, comprising nearly accurate figures of shells drawn by j. mawe, edited by edmund a. crouch, f.l.s. royal to. (published at l s d) _in extra cloth boards_, s d ---- the same, with the plates beautifully coloured, (published at l s) _elegantly bound in gilt cloth_, l s d "this work will be found admirably adapted for the purpose for which it is intended, viz. to introduce to the student the improved system of conchology founded by the celebrated french naturalist lamarck, which is done in a clear and concise manner, by giving a short yet adequate description of the various classes, orders, families, and genera, composing the system; accompanied with illustrations of characteristic and generally well known species, drawn from nature. we can strongly recommend it to the attention of all those who feel interested in this department of natural history. the plates, twenty-two in number, are thickly though not confusedly studded with figures--indeed, considerable taste is displayed in their arrangement; they are beautifully coloured, and have more the appearance of highly finished drawings than merely tinted engravings, and on the whole, it reflects great credit upon the artist-author." _literary gazette._ latham's general history of birds, being the natural history and description of all the birds (above four thousand) hitherto known or described by naturalists, with the synonymes of preceding writers; the second enlarged and improved edition, comprehending all the discoveries in ornithology subsequent to the former publication, and a general index, vols. to. _with upwards of exquisitely coloured plates, elegantly hf. bd. morocco_, l s winchester, - the index sold separately, price s d in boards. this celebrated work was published at twenty-five guineas in boards, with the plates coloured in a very inferior manner. the present copies are all coloured like highly finished drawings, with studious accuracy, under the direction of several eminent ornithologists, and most of the subjects have been compared with living or preserved specimens in the museums and gardens of london. copies coloured in this manner would not have been published at less than fifty guineas. indeed the few copies of the old edition formerly coloured by miss stone, similar in execution but inferior in accuracy to the present, have been sold as high as from fifty to one hundred guineas at the sales of col. stanley, john dent, esq. and sir mark sykes. "no scientific works on natural history ever obtained so much celebrity as those of our venerable countryman dr. latham. his _general history of birds_, which is an enlargement of his _synopsis_, is undoubtedly the most useful and valuable work of its class, that has yet appeared as it contains exact scientific descriptions of every bird known at the time." _neville wood._ lewin's (j. w.) natural history of the birds of new south wales, collected, engraved, and faithfully painted after nature, by john william lewin, late of paramatta, new south wales; third and greatly improved edition, with an index of the scientific names and synonymes to the present time ( ), contributed by mr. gould, mr. eyton, and other scientific gentlemen, folio, _with plates, beautifully coloured_, (published at l s) _neatly hf. bd. morocco_, l s "admirable figures, full of truth and nature; accompanied by valuable observations on the habits and economy of the birds."--_swainson._ "according to the first ornithologists of the day, these plates are of permanent value."--_wood._ lindley's british fruits; or figures and descriptions of the most important varieties of fruit cultivated in great britain, vols. royal vo. _containing most beautifully coloured plates, chiefly by mrs. withers, artist to the horticultural society_, (published at l s) _elegantly hf. bd. green morocco extra, gilt edges_, l s this is an exquisitely beautiful work. every plate is like a highly finished drawing, similar to those in the horticultural transactions. lindley's ladies' botany; or a familiar introduction to the study of the natural system of botany, _new edition_, mo. _with numerous wood-cuts_, (published at s) _elegantly bound in cloth, with gilt back and sides_, s ---- the same, _with the plates coloured, extra gilt cloth_, s "the want of a popular introduction to the study of botany on the improved natural system has been completely removed by this volume of dr. lindley's. it is accurate in its science, graceful in its style, and familiar in its language; it enables the student to take some common, or easily accessible plant, as the representative of each natural family, to examine its several parts, to compare them with the plates, and learn their uses from the descriptions; when he has done this with care, and understood, and remembered what he has done, he will be a botanist; if not a learned one, at least acquainted with all the fundamental facts of the science." _athenæum._ "we are infinitely indebted to professor lindley for leading us so far in the study of botany in a plain and intelligible way. a multitude of plates, a clear text, and a most judicious and agreeable arrangement, render this introduction to perhaps the most innocent and delightful of all studies, truly acceptable." _literary gazette._ mantell's fossils of the south downs, or illustrations of the geology of sussex, royal to. _with plates_, (published at l s) _extra cloth bds_. l s "my attention was first drawn to these remains by mr. mantell, who has illustrated the subject in his excellent work on the fossils of the south downs." _parkinson's organic remains._ "for the detailed history of the organic remains of the wealden formation, see mr. mantell's highly instructive and accurate volume on the geology of sussex." _buckland's bridgewater treatise._ martin's (p. i.) geological memoir on a part of western sussex, with some observations upon chalk-basins, the weald-denudation, and outliers-by-protrusion, to. _large map and coloured plates_, (published at l) _cloth bds._ s mudie's (robt.) history of british birds, or the feathered tribes of the british islands, vols. vo. _second edition, the plates beautifully coloured_, (published at l s) _extra cloth bds. elegantly gilt on the backs_, s "this is, without any exception, the most truly charming work on ornithology which has hitherto appeared, from the days of willughby downwards. other authors describe, mudie paints; other authors give the husk, mudie the kernel. we most heartily concur with the opinion expressed of this work by leigh hunt (a kindred spirit) in the first few numbers of his right pleasant _london journal_. the descriptions of bewick, pennant, lewin, montagu, and even wilson, will not for an instant stand comparison with the spirit-stirring emanations of mudie's 'living pen,' as it has well been called. we are not acquainted with any author who so felicitously unites beauty of style with strength and nerve of expression--he does not specify, he paints." _wood's ornithological guide._ "the '_feathered tribes_' is indeed an exquisite work, and unquestionably the best that has yet appeared on the habits of our native birds, in that it is scarcely second to those of wilson and audubon. mudie is the most accurate observer of nature,--selby excepted, and he treats not exclusively of habits--consequently the '_feathered tribes_' deserves a distinguished place on the shelves of the philosophic ornithologist."--_ornithologist's text book._ parkinson's organic remains of a former world, being an examination of the mineralized remains of the vegetables and animals of the antediluvian world, generally termed extraneous fossils, vols. to. _with coloured plates by sowerby, exhibiting above fossil remains_, (published at l s) _extra cloth bds._ l s this distinguished work is continually referred to by dr. buckland in his bridgewater treatise. "a work on the same subject, equally elegant, comprehensive, and impartial, does not exist in english; nor, as far as we know, in any other language. it is written in a plain, intelligible, and equal style, such as may, with pleasure, be perused by all classes of readers."--_british critic._ "'organic remains of a former world,' replete with interest and instruction."--_dr. mantell._ parkinson's introduction to the study of fossil organic remains; especially those found in the british strata, intended to aid the student in his inquiries respecting the nature of fossils, and their connection with the formation of the earth, rd edition, vo. _illustrated by fossil specimens_, (published at s) _extra cloth bds._ s "in this well-printed volume, which may be called a grammar of oryctology, mr. parkinson has comprised an extensive and well-arranged variety of information on the subject of fossil organic remains; supplying to the learner, an easy and complete introductory manual; and to the well-informed, a text-book of convenient reference. the graphic illustrations are copious and distinct."--_eclectic review._ pursh's flora americÆ septentrionalis; or a systematic arrangement and description of the plants of north america; containing, besides what have been described by preceding authors, many new and rare species, collected during twelve years travels and residence in that country, vols. vo. _with plates_, (published at l s) _cloth_, s ---- the same, _with the plates beautifully coloured_, (published at l s d) _cloth_, l s richardson's fauna boreali-americana, or zoology of north america, containing descriptions of the subjects collected in the late northern expeditions under the command of captain sir john franklin, by john richardson, m.d., wm. swainson, esq., and the rev. wm. kirby, published under the authority of the right hon. the secretary of state for colonial affairs, _with numerous beautifully coloured plates_, vols. to. (published at l s) _cloth_, l s d _the following may be had separately_: vol. . birds, by swainson, _coloured plates_, (published at l s) _cloth_, l s . fishes, by richardson, _coloured plates_, l s . insects, by kirby, _coloured plates_, l s "we cannot speak in too high terms of admiration with regard to that splendid national production the _fauna boreali-americana_. it is undoubtedly the best work of its kind that has ever appeared, and will, we expect, long remain so."--_neville wood._ "whether we consider the condensed mass of novel information, the number of species for the first time introduced to our systems, the accuracy of the scientific details, the beauty and correctness of the illustrations and the whole appearance of the book, it reflects the highest degree of credit upon the authors, the artist, and the government."--_loudon._ selby's magnificent work, the figures of british birds, containing an exact and faithful representation, in their full natural size, of all the known species found in great britain, _ figures in beautifully coloured plates_, vols, elephant folio, (published at l) _elegantly hf. bd. morocco, full gilt back and gilt edges, with glazed paper to the plates_, l s ---- the same, _plain plates_, (published at l s) _hf. bd. calf_, l s the grandest work on ornithology published in this country, the same for british birds that audubon's is for the birds of america. every figure, excepting in a very few instances of extremely large birds, is of the full natural size, beautifully and accurately drawn, with all the spirit of life. "every individual of the falcon and owl families would make a perfect picture of itself, so beautifully and correctly are they executed: they have certainly never been equalled even by gould and audubon." _ornithologist's text book._ "the author has been most successful, especially in the larger birds, and it would be impossible to improve on any of the _raptores_, which for fidelity, boldness, and spirit, are unequalled--every feather is distinct, yet beautifully blended."--_wood's ornithological guide._ selby's illustrations of british ornithology, vols. vo. second edition, (published at l s) _in bds._ s this is the most complete scientific manual of british ornithology yet published. every known british bird is enumerated, with an ample description of its plumage, habits, etc., the scientific as well as familiar names given by different naturalists, and references to all those who have figured it. "selby's is the most masterly work that has ever appeared on the birds of britain, and is quite indispensable to every ornithologist." _ornithologist's text book._ sowerby's manual of conchology, containing a complete introduction to the science, illustrated by upwards of figures of shells, etched on copper-plates, in which the most characteristic examples are given of all the genera established up to the present time, arranged in lamarckian order, accompanied by copious explanations; observations respecting the geographical or geological distribution of each; tabular views of the systems of lamarck and de blainville; a glossary of technical terms, &c. &c. new edition, considerably enlarged and improved, with numerous wood-cuts in the text, now first added, vo. _cloth_, l s ---- the same, coloured plates, _gilt cloth_, l s this is the only work which, in a moderate compass, gives a comprehensive view of conchology, according to the present advanced state of the science. it will not only be found useful to all who wish to acquire an elementary acquaintance with the subject, but also to the proficient, as a book of reference. swainson's zoological illustrations, or original figures and descriptions of new, rare, or interesting animals, selected chiefly from the classes of ornithology, entomology, and conchology, and arranged on the principles of cuvier and other modern zoologists, both series complete, vols. royal vo. _containing_ finely coloured plates, (published at l s) _unbound_, l s ---- the same, _very neatly half-bound morocco, uncut,_ l s *** _this fine work was published in parts at s d each. either of the series, in vols. may be had separately, at £ . s each in parts, or £ . s d half-morocco; but separate parts can only be sold at the original price._ this highly esteemed publication, by one of the most eminent zoologists of the age, has long been considered very scarce, and from its being the sole property of the author has not hitherto been sold under the published price. in consequence, however, of his leaving england, he has thought it advisable to dispose of the whole stock to the advertiser, who now offers the complete copies, which are very few in number, at the low prices affixed. the whole of the figures are original, having been drawn by mr. swainson himself, chiefly from specimens in his own collection, and coloured under his immediate inspection. they are universally allowed to be unrivalled for beauty and fidelity. "it might, perhaps, almost be deemed presumption to offer any remarks on a work emanating from the pen and pencil of, undoubtedly, the first ornithologist of the day, but we feel it our duty to give our readers _some_ idea of the contents of the _zoological illustrations._ it will be sufficient, if we mention that his coloured figures of birds are almost unequalled,--they are certainly not surpassed. the figures are beyond conception lovely and delicate, and it only remains for us to remark, that every philosophic ornithologist must possess the zoological illustrations, if indeed they are now to be had."--_wood's ornithologist's text book._ swainson's exotic conchology, or figures and descriptions of rare, beautiful, or undescribed shells, with new letter-press descriptions, parts, royal to. _containing_ large and beautifully coloured figures of shells, (published at l s) _elegantly half-bound morocco, gilt edges_, l s d each of the six parts may be had separately, at s per part. "many of the most rare and beautiful species of this singularly elegant genus (the volutes), have been figured by swainson in the first plates of his _exotic conchology_, with a verisimilitude that has never been equalled, and probably never will be excelled, by any artist. this talent, combined with his scientific knowledge as a naturalist, must render the above work the most eminent of its kind in this country."--_dubois._ swainson's ornithological drawings, being figures of the rarer and most interesting birds of brazil. complete in parts, royal vo. containing seventy-eight beautifully coloured plates, (published at l s d) _elegantly hf. bd. morocco, in one volume_, l s this exceedingly beautiful work is in very few even of the most complete ornithological libraries, as only copies were printed, and mr. swainson refused to sell any excepting to those who had originally subscribed for them. "mr. swainson's name stands so deservedly high, both as an ornithologist and an artist, that, in introducing this splendid work to the notice of our readers, we shall simply say that we consider it in every respect worthy of its author. farther commendation we feel would be superfluous."--_loudon._ wallich, plantÆ asiaticÆ rariores, parts, imperial folio, _coloured plates_, (published at l) _sewed_, l wilson's american ornithology, or natural history of the birds of the united states; with a continuation by charles lucien bonaparte, prince of musignano, new and enlarged edition, completed by the insertion of above one hundred birds omitted in the original work, and illustrated by valuable notes, with an interesting life of the author, by sir william jardine, bart., f.r.s.e., f.l.s. vols. vo. _with a fine portrait of wilson, and plates, exhibiting figures of birds, accurately engraved, and most beautifully coloured, on glazed drawing paper_, (published at l s) _elegantly hf. bd. morocco, top edges gilt_, l s "the valuable notes and interesting life of wilson added to this new edition are from the pen of sir william jardine, a naturalist of congenial mind in feeling and talent. the plates are better executed than those in the american edition, and the greatest possible attention has been paid to accuracy of colouring. altogether we have rarely seen a more valuable work on natural history, and not one more entertaining."--_literary gazette._ "the splendid work of alexander wilson will always be regarded as a subject of pride by his adopted country, as it certainly is by that which gave him birth (scotland)."--_chambers._ "the history of american birds, by alexander wilson, is equal in elegance to the most distinguished of our own splendid works on ornithology."--_cuvier._ "this is by far the best edition of the american ornithology, both on account of the beautiful plates and the interesting notes of the editor. every ornithologist must, of course, possess the work, and he should if possible procure this edition." _neville wood._ woodville's medical botany, containing systematic descriptions of medicinal plants, with a circumstantial account of their effects, and of the diseases in which they have been most successfully employed, third edition, to which is added a supplementary volume, by sir william jackson hooker, _illustrated by coloured plates by sowerby_, vols. to. (published at l s) _half-bound morocco, uncut_, l s ---- the fifth or supplementary volume, entirely by sir w. j. hooker, with coloured plates, to complete the old editions, (published at £ . s. d.) cloth boards, £ . s. d. no well-stored english library should be without woodville's medical botany, a work of long-established reputation, and the best on a subject which must, more or less, be interesting to every man of inquiry. it contains accurate figures and descriptions of all the plants used in english medicine, and is of such authority with professional men, as to be almost as essential to them as the pharmacopoeia itself. subsequent publications of a similar kind, though with woodville as their text-book, have fallen greatly short of the original, as well in comprehensiveness of plan, as in accuracy of delineation and correctness of colouring. it having long been a matter of regret that so excellent a work, from the want of a new edition, should remain so much behind the present state of pharmaceutical science, sir william undertook to supply this defect, by adding a supplementary volume, containing all the new and acknowledged discoveries, and all the plants added to the pharmacopoeias since the publication of the work in . new plates have likewise been given for the _cinchonas_, and other plants, which were not properly identified in the time of woodville; and new letter-press or _errata_ for such descriptions as were deficient or incorrect. all these alterations and additions have been given in the supplementary or fifth volume, preserving everything contained in the original work, inclusive even of the incorrect plates and letter-press, though duplicate, leaving it to the purchaser's option either to cancel or retain them, as he pleases. * * * * * _just published, in imperial vo. price, coloured, £ s. plain, s._ part i of the thesaurus conchyliorum, by g. b. sowerby, jun. containing descriptions of all the species hitherto known of the following genera of shells; helicina, pupina, rostellaria, aporrhais, struthiolaria and strombus, accompanied by highly finished coloured engravings. this work is commenced, and will be continued on a more extensive, complete, and economic plan than has hitherto been attempted. it is intended to be so complete as to supersede the necessity of keeping an extensive conchological library, or of consulting a variety of books for the purpose of identifying species. it will form a complete conchological library in itself. the vast increase in the number of species, either undescribed or published in miscellaneous works, and voyages; the difficulty of obtaining such works, or of naming species without them, and the confusion of synonymes which has been the result, are facts which prove the importance of the present undertaking. the facilities enjoyed by the author, in having access to several of the most important collections; and obtaining the fullest information respecting the localities of subjects by those who have sought them in their native abodes, will, it is trusted, enable him to supply a generally acknowledged desideratum. he hopes to do this in such a manner as to fulfil the expectations of his friends, who may rest assured that neither pains nor expense will be spared to ensure the correctness, completeness, and beauty of the work. the plan of the work is as follows:--it will consist of a complete series of monographs of genera of shells. all the species and varieties of each genus will be described and figured. the essential characters will be given in latin. the explanations and general information will be expressed in english. the figures of average sized shells will be reduced to half the real diameter; those of larger size will be still further reduced; and those of small size will be represented of the natural dimensions. the size of the book is imperial octavo. the paper, printing, engraving and colouring of the best description. a part, containing several monographs will appear every third month, or oftener if possible, the price of each part to depend upon the number of figures which it contains, at the rate of one penny for each figure. the nd part will appear on the st of august. * * * * * the conchological illustrations, _or, figures of hitherto unfigured recent shells, part to _, price, s. d. each, may now be had with indices complete. none of the genera contained in this work will be given in the thesaurus until all the other genera are exhausted. * * * * * sowerby, naturalist. no. , great russell street, bloomsbury. * * * * * corrections made to printed text anomia: "sub-equilateral" corrected from "sub-equilaternal" argonauta: "cephalopoda" corrected from "cepholopoda" ib. "the argonaut is the testaceous part" corrected from "... agonaut ..." haliotis: "oblique" corrected from "obilque" polylepas: "lepas, rock." corrected from "lepas, linn." rhinodomus: "no internal groove" corrected from "... grove" . "panopæa australis" corrected from "... ausrtalis" heading: "fam. brachiopoda" corrected from "... brachipoda" illustrated index of british shells. containing figures of all the recent species, with names and other information. by g. b. sowerby, f.l.s. london: simpkin, marshall, and co., paternoster row; and the author, , pembroke square, kensington. . * * * * * preface. the first idea of this work arose from the occasional use of mr. damon's 'catalogue of the shells of great britain and ireland,' named after the 'history of british mollusca,' etc. here was, on one side, a very useful list of names, without figures or references to guide an inquirer to the species; and on the other, a very large and splendid work, placed by its heavy price beyond the reach of naturalists in general. there was nothing between the two; nothing within reach that would assist collectors of british shells to name their acquisitions from ocean, beach, river, pond, or hedgerow. a public want seemed here to be discovered. it was thought that a list like the above, with a coloured drawing of every species, if produced at an available price, would supply that want. at first no more than this was thought of, but afterwards, as the preparations advanced, various suggestions were made tending to some extension of the plan. the results are here presented. about figures in the plates represent all the recognized species. they amount to , being more than are admitted in the latest monograph. the greater part of these are either new or newly introduced as british. the rest are raised from varieties to species. as the nomenclature used by messrs. forbes and hanley in their great work will be most generally adopted in this country, it is followed here with very few alterations; and the synonyms given (in italics) are selected from those which are most familiar and likely to be met with. some information is added respecting habits and localities, range of depth of marine species, and comparative abundance. the letters c., cc., mc., r., rr., and mr., signifying 'common,' 'extremely common,' 'moderately common,' 'rare,' etc., must be taken with great caution, especially the latter, as subject to continual change. a list is given of british fossil shells identical with now living species. a familiar description of british mollusca and some peculiarities in their families and genera will, it is hoped, form a useful and suitable introduction to the names and figures. the author's best thanks are due to his friends, madame de burgh, who has collected many beautiful shells; r. mcandrew, esq., f.l.s., whose dredging experiences are so extensive; j. g. jeffreys, esq., f.r.s., etc., whose researches have resulted in so many additions to our fauna; mr. brice wright, the naturalist, of great russell street, and others, who have in the most liberal manner supplied him with specimens from which his drawings are taken. the loan of delicate and minute shells to authors and artists has so often proved disastrous, that nothing but a generous friendship, and a zealous love of natural history, could have induced proprietors so freely to incur the risk. * * * * * introduction to shell-bearing british mollusca. a common garden snail, observed crawling and feeding, is easily seen to possess a distinct head, upon which are four feelers or horns, with eyes at the end, and underneath which is a mouth; a broad disc, extending the whole length of the body, is the organ of locomotion; a spiral or coiled shell surmounts the whole. if, on the other hand, an oyster be opened, no distinct head, or place for eyes or mouth, can be seen, but only a seeming mass of pulp, with a round gristle in the centre (the muscle of attachment), the former enclosed in a soft skin with a double fringe round the edge (mantle), placed within a shell composed of two pieces. all mollusca are more or less completely represented by these two. the snail and its class are named _gasteropoda_ (abdomen-creeping), and their shells _univalves_; the oyster and its class, _acephala_ (headless), and their shells _bivalves_. we begin with the latter class at-- plate i. _pholadidæ_, or "borers," - , have the power of piercing and inhabiting holes in submarine wood, rocks, and stones. the hinder part of the body is lengthened out in the form of a double tube, with openings for the ingress and egress of fluids. _teredo_, - , has short valves, two pallets fixed at the sides of the siphons, and lines its hole with a shelly tube. _pholas_ and _pholadidea_, - , have long valves and sometimes accessory plates. the shell of _xylophaga_, , is like that of _teredo_, but the animal has neither pallets nor tube. _gastrochæna_, , has a gaping shell, and encloses itself in a bottle-shaped covering of cemented stones and sand. _saxicava_, , , _venerupis_, , and _petricola_, , burrow in sand, or live in holes of rocks. _myadæ_, or "gapers," _mya_, , , and _panopæa_, , *, burrow downwards in sand and mud, their siphons protected by a coriaceous covering. their shells are not closed all round, and those of _mya_ have a spoon-shaped process in the hinge of one valve. _corbulidæ_, - , have short siphons with fringed edges, and the foot protrudes through a hole in the otherwise closed mantle. plate ii. _poromya_, , *, and the beautiful pearly _pandora_, , , might be included in the family of _corbulidæ_. _lyonsia_, , and _thracia_, - , represent the _anatinidæ_. - are _solenidæ_, or "razor-shells." solens burrow in deep holes in the sand, where they remain in a perpendicular position at a great depth below the surface, where yet their presence may be traced by the opening left. their large muscular foot enables them to take great leaps when out of the holes. plate iii. _psammobia_, - , and _tellina_, - , include some of our most beautiful shells. the animals have a large, fleshy, curved foot, and the mantle open and fringed. their shells are provided with an external ligament, and teeth on the hinge. _donax_, or "wedge," , , has long, separated, fringed siphons. besides the small external ligament, properly so called, the _mactridæ_ have a triangular pit in the hinge of their shell, containing an elastic substance or spring, designed to resist the action of the adductor muscles. _mactra_, - , ends the plate. plate iv. _lutraria_, - , is another genus of _mactridæ_. the _veneridæ_, - and , or "venus" tribe, differ from it in not having the spring-holding pit. _artemis_, , , is known by a large angular bend in the pallial impression; and _cytherea_, , is distinguished from venus by one tooth on the hinge standing out a little way from the central ones. _astarte_, - , belongs to the _cyprinidæ_. plate v. fig. - also represent genera of _cyprinidæ_. they have no bend in the palleal impression. _cardium_, or "cockle," - , presents a peculiarity in the foot, which is large and bent, and enables the animal to leap in a very lively manner. the family of _lucinidæ_ occupy the remaining figures. _lucina_ has a curious tongue-shaped doubling of the pallial impression. plate vi. the _kelliadæ_, - , are marine, while the _cycladidæ_, completing the plate, are fresh-water bivalves, and may be found in many ponds and rivers. plate vii. of the _unionidæ_, or "fresh-water mussels," _unio_, - , has teeth on the hinge, and _anodon_, , has not: it is a thin shell. the foot of these molluscs is very large, and is used in cutting the animal's way through the mud in which it burrows. of the marine, or true mussels, _modiola_, - , and _crenella_, - , have a portion of the shell reaching beyond the point or apex, which in _mytilus_ is terminal, - . _dreissina_, , is shaped like _mytilus_, but lives in fresh-water docks. the _mytilidæ_ attach themselves by means of horny threads spun from the foot, and called a "byssus." plate viii. shells of _arcadæ_, - , have the hinge characterized by a series of teeth on each side of the apex. _nucula_, _arca_, and _pectunculus_ are easily distinguished. _limopsis_, , has a spring pit between the two rows. our figure of _pinna_, , is from a young specimen: it grows to great size, and spins a very silky byssus. the shell of _anomia_, , is fixed to rocks, etc., by means of a bony button passing through a hole or sinus in the lower valve. _lima_, - , has a light, thin shell, and its mantle is adorned with beautiful fringes. it swims rapidly through the water by the opening and shutting of its valves, and also has the habit, in seasons of rest, of protecting itself by a network or vest of marine fragments strung together by its byssal threads. plate ix. contains the shells of our pectens, or scallops, - . the animals swim like _lima_, as above, and also spin a byssus. the class _brachiopoda_, - , so named because what seem to be organs of locomotion consist of a pair of coiled, ciliated arms, ends the list of headless molluscs and their bivalve shells. plate x. class _pteropoda_, - , contains minute mollusca, with glassy shells variously formed, and wing-like expansions for swimming. _chiton_, - , or "coat of mail," which may often be seen incrusting rocks, commences the _gasteropoda_; although seemingly fixed, they are capable of locomotion, using the whole of the oval disc, which may be seen on turning them over, for the purpose. the same may be said of the "limpet" tribe, _patella_, - . plate xi. this plate commences with other forms of the limpet tribe, _fissurella_, , , with a hole at the top; _puncturella_, , with a fissure near the top; and _emarginula_, - , with a slit at the margin. _haliotis_, , or pearly "ear-shell," leads to the _trochidæ_, or "tops," - . plate xii. _ianthina_, - , is genus of oceanic molluscs, which are provided with a beautiful floating apparatus, on which the female carries her egg-bags. _neritina_, , and the _paludinidæ_, - , live in fresh-water. the animal of _paludina_ is sprinkled all over with bright, golden specks. the _littorinæ_, or "winkles," - , are marine, and frequent the shore among seaweeds. _lacuna_, - , belongs to the same family. plate xiii., xiv. are small genera, various in their characters and habits, but reasonably included in the last family, _littorinidæ_. plate xv. the animals of _turritella_, - , and _cæcum_, , , are not unlike, although the shells are so different; eyes at the base of the tentacles, a short foot, and horny operculum. the somewhat similar animal of _aporrhais_, , , is brilliantly coloured with gold and red. _cerithium_, - , differs from _cerithiopsis_, - , more in regard to the animal than the shell; the latter animal has a retractile proboscis, and its operculum is not spiral. plate xvi. _chemnitzia_, - , and _truncatella_, , together with _stylifer_, _eulima_, and _odostomia_, form the family of _pyramidellidæ_. notwithstanding the difference in the shells, the animals are very similar, having a retractile proboscis, and eyes immersed at the base of their tentacles. the animal of _natica_, - , has a lobe on the upper part of the foot, reflected over the shell in front, and another lobe behind. the shells of _laminaria_, , , are completely enveloped in similar lobes. plate xvii. the shells of _odostomia_ are known by a fold in the inner lip of the aperture. plate xviii. two _tritons_, , , are admitted for the first time as british, on what we consider fair evidence, although only two or three specimens have been taken off guernsey. one of _t. nodiferus_ was incrusted by a truly british _lepralia_. _murex_, , is now familiar as an aquarian, as well as _purpura_, . a milky secretion found in the head turns purple when exposed, and gives the celebrated purple dye. _buccinum_, - , includes the common "whelk," . _fusus berniciensis_, , is among the rarest and most beautiful of our british shells. plate xix. _nassa reticulata_, , is a favourite inhabitant of the tank; it burrows in search of food among the pebbles, elevating its siphon above the surface. _mangelia_, - , has a similar long siphon. the shell of _erato_, , is wrapped in the lobes of the animal's mantle, as is also that of _cyprea_, , the latter presenting a beautiful object. plate xx. after _tornatella_, , and _ovula_, , , come _bullidæ_, - , including several genera differing remarkably in the shape and disposition of the lobes of their mantles, which in some instances, as in _philine_, - , cover the shell. the stomach of _scapander_, , , is a remarkable kind of mill, composed of two bones, between which the food is ground. the shells of _aplysia_, , and _pleurotranchus_, , , are quite internal. _spirula_, , belonging to the cephalopodous or cuttlefish tribe, is only introduced doubtfully, as there is no proof of the species living in our seas. plate xxi., xxii., xxiii., xxiv. these are occupied by shells of _gasteropoda pulmonifera_, so named because they breathe air by a pulmonary cavity, instead of water by gills. the _limnæadæ_, or fresh-water snails, contained in plate i., live in water, but breathe by exposing the pulmonary cavity to air at the surface. _succinea_, plate xxii., - , lives by the sides of streams, sometimes immersed. _conovulus_, - , affects brackish marshes. our common slugs yield, on dissection, thin shells, which are concealed beneath the mantle, _limax_, - . the shells of _testacellus_, , , are fixed near the end of the foot, outside. the glassy shells of _vitrina_, , , do not enclose the whole slug-like animal. the other genera of land snails have shells large enough to receive the animal when retracted and withdrawn for repose. * * * * * british fossil shells. the following living species are also found in a fossil state in drift and strata of the british isles. they are all enumerated in mr. searles wood's monograph of the crag mollusca. the numbers refer to the species as figured in our plates, mr. wood's nomenclature being inserted in italics when differing from ours. pl. i. teredo . pholas . pholadidea . gastrochæna , as _dubia_. saxicava , . venerupis . mya , . panopea , *, as _faujasii_. corbula , ? sphænia . neæra . pl. ii. poromya . pandora , as _inæquivalvis_, , as _pinna_. thracia , . solen, , . solecurtus , as _mactra strigilata_. syndosmya, as _abra_, , . pl. iii. psammobia , , . tellina , , , , as _ovata_, , as _balthica_, . scrobicularia , as _trigonella plana_. donax , as _vittatus_. mactra , , , as _ovalis_, , , . pl. iv. lutraria . tapes , . artemis . venus , , , . astarte , , , , as _borealis_. pl. v. cyprina . circe . isocardia . cardium , , , , . lucina , as _loripes_, , as _cryptodon flexuosum_, . diplodonta . clausina , as _cryptodon f._ pl. vi. montacuta , , . kellia , . poronia , as _kellia r._ cyclas , . pisidium , , , . pl. vii. unio , . anodon . modiola , , . crenella , , , . mytilus , , . pl. viii. nucula , . leda , . area , , , as _pectunculoides_. pectunculus . avicula . pinna . ostrea . anomia , , , . lima , , . pl. ix. pecten , , , , , , , , , . pl. x. chiton , as _fascicularis_. patella . acme . propilidium, as _tectura_, . dentalium , . capulus . calyptræa . pl. xi. fissurella , as _græca_. puncturella . emarginula , . trochus , , , , as _papillosus_, , , , . margarita . adeorbis . scissurella . pl. xii. paludina . valvata . littorina . lacuna . pl. xiii. rissoa *, as _paludestrina subumbilicata_, , ?, ?, , , . pl. xiv. rissoa , , as _chemnitzia_. aclis , as _alvania ascaris_, , as _chemnitzia n._ pl. xv. turritella . aporrhais . cæcum , . cerithium , . cerithiopsis, as _cerithium_, . scalaria , , . eulima , . pl. xvi. chemnitzia , , as _similis_, , . natica , , as _catena_, , as _groenlandica_. velutina . trichotropis . pl. xvii. odostomia , , as _plicata_, , as _plicata_, ?, . pl. xviii. purpura . buccinum ? fusus , as _trophon_, , as _tr._, , as _tr. gracile_, , as _tr. t._, , as _tr. p._ trophon , . pl. xix. nassa , . mangelia, as _clavatula_, , , , as _philberti_, , , as _boothii_, , , , ?, , . erato . cypræa . pl. xx. tornatella , as _actæon tornatilis_. ovula , as _bulla_. cylichna, as _bulla_, , , as _regulbiensis_, , , . bulla . philine as _bullæa_, , . scaphander, as _bulla_, . pl. xxi. limnæa , , , . planorbis , , as _complanatus_, and in the upper fresh-water formation, all except , . pl. xxii. succinea , . conovulus , and in the more recent fresh-water deposits, all except and to . pl. xxiii. helix , , and upper fresh-water, all except , , , , , , . pl. xxiv. upper fresh-water deposits, all except , . * * * * * index to the genera. referring to plates and figures. achatina, xxiv. . aclis, xiv. , . acmæa, x. , . acme, xxiv. . adeorbis, xi. . akera, xx. . amphispira, xx. , . ancylus, xxi. - . anodonta, vii. . anomia, viii. - . aplysia, xx. . aporrhais, xv. , . arca, viii. - . argiope, ix. , . artemis, iv. , . assiminea, xiii. , . astarte, iv. , . avicula, viii. . azeca, xxiv. . balea, xxiv. . barleeia, xiv. . bithinea, xii. , . buccinum, xviii. - . bulla, xx. - . bulimus, xxiv. - . calyptræa, x. . _capulus_, pileopsis. cardium, v. - . carychium, xxii. . cæcum, xv. - . _cemoria_, puncturella. ceratisolen, ii. . cerithiopsis, xv. - . cerithium, xv. - . chemnitzia, xvi. - . chiton, x. - . circe, v. . _clavatula_, mangelia. clausilia, xxiv. - . clausina, v. - . cochlodesma, ii. . conovulus, xxii. - . corbula, i. - . crania, ix. . crenella, vii. - . cyclostoma, xxiv. . cyclas, vi. - . cylichna, xx. - . cypræa, xix. . cyprina, v. . cytherea, iv. . dentalium, x. , . diodonta, ii. , *. diplodonta, v. . donax, iii. , . dreissina, vii. . emarginula, xi. - . euomphalus, xiv. , . ervillia, iii. . eulima, xv. - . eulimella, xiv. - . fissurella, xi. , . fusus, xviii. - . galeomma, vi. , . gastrochæna, i. . haliotis, xi. . _helix_ (zonites), xxii. - . helix, xxiii. - . _hinnites_, pecten, ix. . hippothyris, ix. . hyalæa, x. . ianthina, xii. - . isocardia, v. . jeffreysia, xiv. - . kellia, vi. - . lachesis, xviii. . lacuna, xii. - . lamellaria, xvi. , . leda, viii. , . lepton, vi. - . lima, viii. - . limax, xxii. - . limnæa, xxi. - . limopsis, viii. . littorina, xii. - . lucina, v. - . lucinopsis, iv. . lutraria, iv. - . lyonsia, ii. . mactra, iii. - . mangelia, xix. - . margarita, xi. - . _marginella_, erato. _megathyris_, argiope. modiola, vii. - . montacuta, vi. - . murex, xviii. , . mya, i. - . mytilus, vii. - . nassa, xix. - . natica, xvi. - . neæra, i. - . neritina, xii. . nucula, viii. - . odostomia, xvii. - . ostrea, viii. . otina, xvi. . ovula, xx. , . paludina, xii. , . pandora, ii. , . panopæa, i. , *. patella, x. - . pecten, ix. - . pectunculus, viii. . petricola, i. . phasianella, xi. . philine, xx. - . pholas, i. - , . pholadidea, i. . physa, xxi. , . pileopsis, x. . pilidium, x. . pinna, viii. . pisidium, vi. - . planorbis, xxi. - . pleurobranchus, xx. . _pleurotoma_, mangelia. poromya, ii. , *, ix. propilidium, x. . psammobia, iii. - . puncturella, xi. . pupa, xxiv. - . purpura, xviii. . recluzia, xvi. . rissoa, xiii. - ; xiv. saxicava, i. , . scalaria, xv. - . scaphander, xx. , . scrobicularia, iii. . scissurella, xi. . _segmentina_, planorbis, xxi. , . skenea, xiv. - . solen, ii. - . solecurtus, ii. , . spirialis, x. - . spirula, xx. . stylifer, xv. . succinea, xxii. - . syndosmya, ii. - . sphænia, i. . tapes, iv. - . tellina, iii. - . terebratula, ix. - . teredo, i. - . testacellus, xxii. , . thracia, ii. - . tornatella, xx. . trichotropis, xvi. . triton, xviii. , . trochus, xi. - . trophon, xviii. - . truncatella, xvi. . turritella, xv. - . turtonia, vi. . unio, vii. - . valvata, xii. , . velutina, xvi. , . venerupis, i. . venus, iv. - . _vertigo_, pupa. vitrina, xxii. - . xylophaga, i. . zonites, xxii. - . zua, xxiv. . [illustration: british shells. plate i.] plate i. teredo. pierces and inhabits wood. fig. . t. navalis, _linn._--_t. batavæ._--herne bay, r. pallets shelly, crescented; valves with auricles extended sidewise; tube long. . t. norvegica, _spengl._--_t. bruguieri._--port patrick, teignmouth, etc., mc. pallets shelly, not crescented; auricles not extended. . t. megotara, _hanl._--_t. nana_ (young).--herne bay, devon, swansea, etc., r. pallets shelly, spade-shaped; auricles raised and expanded. . t. bipennata, _turt._--ireland, scarborough, etc., r. pallets horny, long; auricles lobed. . t. malleolus, _turt._--torquay, rr. pallets shelly, mallet-shaped; valves narrow. . t. palmulata, _lamk._--_t. bipalmulata._--floating wood, ire., s. eng. pallets horny, short; valves small, shaped like _t. navalis_. xylophaga. in fixed and floating timber. . x. dorsalis, _turt._--ayrs., dubl., exm., scarb., etc., c. two dorsal plates, no tube, no pallets. pholas. pierces and inhabits stone. . p. dactylus, _linn._--_p. hians_, _p. callosa_.--eng., scot., ire., c. dorsal plates four; hinge pitted. . p. candida, _linn._--eng., scot., ire., c. one dorsal plate; valves not beaked. . p. parva, _penn._--_p. callosa_, _p. tuberculata_.--salcombe, belfast, cornwall, etc., m. c. one dorsal plate; valves beaked. . p. crispata, _linn._--_p. bifrons._--hastings, liverp., scarb., dubl., forth, etc., c. no dorsal plate; valves broad, beaked, with oblique division. . p. striata. rare and doubtful as british. valves closed. pholadidea. pierces and inhabits stone. . p. papyracea, _p. loscombiana_, _p. goodalli._--s. devon, n. ire., r. valves closed, with a cup. _p. lamellata_, turt., when young, not closed; no cup. gastrochÆna. bores and inhabits stone, thick shells, etc. . g. modiolina, _lamk._--_g. pholadia_, _g. hians_, _mya dubia_, _mytilus ambiguus_, _pholas faba_.--torbay, birterbuy, galway, weymouth, etc. valves thin, gaping, enclosed in bottle-shaped tube. saxicava. bores and inhabits stone. . s. rugosa, _linn._--_mytilus r._, _hiatella r._, _s. gallicana_, _s. pholadis_, _byssomya pholadis_, _mya byssifera_.--eng., scot., ire., c. valves oval. . s. arctica, _linn._--(_mya_) _hiatella a._, _anatina a_., _hiatella minuta_, _solen minutus_, _s. rhomboides_, _agina purpurea_, _solen p._--eng., scot., ire., c. valves rhomboidal; angle serrated. _omitted._--s. fragilis, _nyst._ _not_ the young of _s. rugosa_. vigo bay. petricola. inhabits stone. . p. lithophaga, _retz._--_p. striata_, _costellata_, _rocellaria_, _ruperella_, lamk., _mya_ and _sphænia decussata_.--cork, bristol, r. as british. venerupis. bores and inhabits stone. . v. irus, _linn._ (donax).--_tellina cornubiensis_, _cuneus foliaceus_, _petric._, and _pullastra_, i.--in limestone at plymouth and other southern coasts. wedge-shaped. mya. burrows in mud and sand. . m. truncata, _linn._--_m. ovalis_ and _sphænia swainsoni_ (young).--various localities and depths, c. truncated at end. . m. arenaria, _linn._--herne bay, portsmouth, etc., c. tapering at end. panopÆa. burrows in mud. . p. norvegica, _spengl._--_p. glycimeris_, _p. arctica_.--scarborough, zetland ( fath.), rr. quadrate. *. p. aldrovandi, _lamk._--cornwall, one specimen, _jeffreys_. oblique. corbula. dredged in mud and sand. . c. nucleus, _lamk._--_c. striata_, _mya_, and _c. inæquivalvis_.--dublin, torquay, forth, to fath., c. valves unequal, beaked. . c. rosea, _brown_.--weymouth, rr. as brit. valves not beaked. . c. ovata, _forbes_.--isle of man, rr. oval, truncated at end. sphÆnia. burrows in foliaceous shells. . s. binghami, _turt._--_corbula b._--torquay, guernsey, swansea, forth, etc., r. neÆra. lives incrusted in sand. . n. costellata, _desh._--_corbula c._, _n. sulcata_.--loch fyne, rr. radiately -ribbed. . n. cuspidata, _olivi_.--forth, northumberland, cape clear, etc., mr. pear-shaped. . n. abbreviata, _forbes_.--loch fyne, mc. radiately -ribbed. [illustration: british shells. plate ii.] plate ii. poromya. on mud, in deep water. fig. . p. granulata, _nyst._--_p. anatinoides_, forbes.--skye, r. *. p. subtrigona, _jeffreys_.--shetland, mr. minute, posteriorly expanded. see pl. ix. pandora. . p. rostrata, _lamk._--_tellina inæquivalvis_, linn.; _p. margaritacea_ and _inæquivalvis_.--s. devon?, guernsey, r. as brit. valves long. . p. obtusa, _leach_.--_solen pinna_, mont.--s. devon, dorset, mc. ire., r. valves short and broad. lyonsia. with byssal attachment. . l. norvegica, _chemn._--_mya_ and _anatina n._, _mya_ and _anatina striata_, _m. nitida_, _lyonsia elongata_, _myatella_, and _osteodesma_.--tenby, bantry, oban, etc., to fath. with movable ossicle on hinge. thracia. laminarian and coralline. . t. distorta, _mont._--(_mya_) _anatina_ and _amphidesma d._, _th. truncata_.--distribution general, but not common. short, truncated, irregular. . t. convexa, _wood_.--(_mya_) _anatina_ and _amphidesma c._, _t. declivis_.--s. devon, bantry bay, arran, etc., mc. inflated. . t. phaseolina, _lamk._--_amphidesma p._, _t. declivis_.--various localities and depths, c. oval, obliquely truncated. . t. pubescens, _pult._--(_mya_) _anatina_ and _amphidesma p._, _t. declivis_.--s. devon, cornwall, belfast, etc., c. oblong, straightly truncated. . t. villiosulca, _macgillivray_.--_t. ovata_, brown.--exmouth, swansea, bantry bay, etc. various depths, mc. cochlodesma. laminarian and coralline. . c. prÆtenue, _pult._--(_mya_) _anatina_, _ligula_, and _amphidesma pr._--dorset, devon, man, bantry b., oban, etc., ( to fath.), r. spoon-shaped process on hinge. ceratisolen. burrows in sand. . c. legumen, _linn._--(_solen_) _psammoiia_ and _solenicurtus l._--exmouth, swansea, bantry, etc., c. hinge nearly central. solen. burrows perpendicularly in sand. . s. pellucidus, _penn._--various british localities, to fath. curved; hinge not terminal. . s. ensis, _linn._--eng., scot., ire., generally to fath., c. arched and slender. . s. marginatus, _pult._--_s. vagina_, penn., not linn.--exmouth, clyde, cork, etc., littoral to fath., mc. straight, with terminal constriction. . s. siliqua, _linn._--_s. novacula_, _s. ligula_.--eng., scot., ire., many places; littoral and laminarian, c. straight, end not constricted. diodonta. . d. fragilis, _linn._--(_tellina_) _psammobia f._, _tellina jugosa_ and _ochroleuca_.--dublin, tenby, weymouth, r. oval or wedge-shaped. *. d. barleei, _jeffr._--arran, rr. minute, subquadrate. solecurtus. . s. coarctatus, _gmel._--_s. cultellus_, _s. emarginatus_, _s. antiquatus_, etc.--torbay, anglesea, man, skye, etc., r. oblong, smooth. . s. candidus, _renieri._--(_solen_) _s. strigilatus_, turt., not linn., _psammobia scopula_.--s. devon, dublin, etc., r. striated. syndosmya. . s. prismatica, _mont._--(_ligula_) _mya_ and _amphidesma p._--weymouth, forth, dublin, antrim, etc., littoral, mc. more pointed and narrow than _s. intermedia_. . s. tenuis, _mont._--(_mactra_) _amphidesma t._--dorset, scarborough, antrim, etc., to fath., mc. short, subtrigonal. . s. intermedia, _thompson._--_mya_ and _syndosmya nitida_, _abra profundissima_.--in mud, to fath., zetland, skye, cape clear, etc., r. broader and more pointed than _s. prismatica_. . s. alba, _wood._--(_mactra_) _m._ and _amphidesma boysii_ and _a. album_.--brit. co. generally, c. short, rounded, oval. [illustration: british shells. plate iii.] plate iii. psammobia. inhabits sand and mud. fig. . p. ferroensis, _chemn._--(_tellina_) _t. incarnata_, _t. radiata_, _t. trifasciata_, _t. truncata_.--brit. co. generally; coralline, c. oblong, keeled and angulated behind. . p. costulata, _turt._--_p. discors._--torbay, cornwall, skye, etc., r. ribbed behind. . p. tellinella, lamk.--_p. florida._--exmouth, guernsey, tenby, bantry b., oban, zetland, etc., to fath., c. oval, smooth. . p. vespertina, _chemn._--(_lux v._) _solen_, _sanguinolaria v._, _tellina depressa_, _variabilis_.--weymouth, scarborough, tenby, bantry, etc., guernsey, c. not angular nor keeled behind. tellina. . t. crassa, _penn._--_t. maculata_, _t. rigida_.--s. devon, guernsey, man, tenby, bantry, forth, etc., low-water to fath., c. thick, orbicular. . t. balaustina, _linn._--birterbuy, skye, exmouth, rr. as british. . t. donacina, _linn._--_t. trifasciata_, _t. variegata_, _t. llantivyi_.--various british loc., and s. europe, to fath., c. wedge-shaped. , . t. proxima, _brown._--var. _t. calcarea_ ( ), _t. ovalis_, _t. sordida_, _sanguinolaria sordida_, _macroma tenera_.--skye, etc., r. , . t. pygmÆa, _phil._--devon, cork, shetland, etc., to fath., c. smaller, more convex, and more truncate than _t. donacina_. , . t. tenuis, _da costa._--_t. planata_, _t. polita_, _t. exigua_.--on sandy shores, in various localities, c. flat, thin. . t. incarnata, _linn._--_t. squalida_, _t. depressa_.--devon, bantry, tenby, r. flat, beaked. . t. solidula, _pult._--_t. rubra_, da costa, _t. carnaria_, _t. zonata_, _psammobia solidula_, _t. balthica_.--all british coasts; littoral, c. thick, inflated. . t. fabula, _gronovius._--_t. discors._--on sandy shores generally, c. valve with oblique striæ (omitted by error). ervillia. . e. castanea, _mont._--(_donax_) _mesodesma c._, _capsa c._--cornwall and scilly isles, r. ligament within. scrobicularia. . s. piperita, _gmel._--generic syn.: _mya_, _venus_, _trigonella_, _mactra_, _lutraria_, _listera_.--specific syn.: _hispanica_, _borealis_, _plana_, _gaditana_, _listeri_, _compressa_.--scarborough, southend, swansea, cork, clyde, c. broad, compressed. donax. . d. anatinus, _lamk._--_d. trunculus_, linn.?, _cuneus vittatus_, _d. ruber_ (young).--brit. co. generally, sandy shores, c. broad; margin crenulated. . d. politus, _poci._--(_tellina_) _d._ and _capsa complanata_.--s. devon, bantry bay, etc., mr. smooth; inner edge not crenated. mactra. lives on sandy beaches. . m. stultorum, _linn._--(_cardium_) _tellina radiata_, _trigonella r._, _m. cinerea_, _m. magna_.--british co. generally, c. . m. elliptica, _brown._--british co. generally, c. oval. . m. subtruncata, _costa._--_m. lactea_, _m. triangula_, _m. crassatella_.--brit. co. generally, c. obliquely cuneiform. . m. helvacea, _chemn._--_m. glauca_, _m. neapolitana_.--odd valves found dead in cornwall, r. large, obliquely oval. . m. solida, _linn._--_trigonella zonaria_ and _gallina_.--brit. co. generally, c. trigonal, thick. . m. truncata, _mont._--forth, cork, cornwall, etc., c. trigonal, deep, thick. [illustration: british shells. plate iv.] plate iv. lutraria. inhabits mud. fig. . l. intermedia?, _sowb._--perhaps only the young of _l. elliptica_. . l. elliptica, _lamk._--_mactra lutraria_, linn.--scarborough, torbay, dublin, forth, lerwick, etc., c. broad, oval. . l. oblonga, _chemn._--(_mya_) _l. solenoides_, _l. hians_, _mactra hians_, _chama magna_.--cornwall, devon, etc., mc. arched, narrow. tapes. burrows in mud and stone. , . t. pullastra, _wood._--_venus pullastra_, _v. perforans_ (var. f. ), _venerupis nucleus_, _pullastra vulgaris_, etc.--plymouth, scarborough, swansea, forth, etc., c. . t. decussata, _linn._--(_venus_) _v. litterata_, _v. florida_, _venerupis_ and _pullastra d._--s. devon, weymouth, tenby, etc., mc. oblong, coarsely decussated. . t. aurea, _gmel._--(_venus_) _v. nebulosa_, _v. ænea_, _v. nitens_, _v. sinuata_, _pullastra a._--cornwall, sussex, bantry bay, loch ryan, mc. yellow within. . t. virginea, _linn._--(_venus_) _v. rhomboides_, _v. sarniensis_, _v. virago_, _cuneus fasciatus_.--various british loc., c. pink within. lucinopsis, _forbes_ and _hanley_. sandy ground. . l. undata, _pennant._--(_venus_) _v. sinuosa_, _v. incorrupta_, _lucina undata_.--exm., scarborough, man, etc., to fathoms, m.r. orbicular, flexuous at side. artemis. . a. exoleta, _linn._--(_venus_) _cytherea e._, _pectunculus capillaceus_.--sandy ground, on brit. co. generally, low-water to fath., c. compressed; striæ coarse. . a. lincta, _pult._--(_venus_) _v. sinuata_, _cytherea sinuata_.--various brit, loc., c. dorsal edge sloping; striæ fine. venus. . v. casina, _linn._--_v. reflexa_, _v. lactea_, _v. discina_.--northumberland, s. devon, man, bantry, skye, etc., mc. concentrically laminated. . v. verrucosa, _linn._--_v. erycina_, _v. cancellata_, etc.--devon, cornwall, channel isls., etc., c. ventricose, warted. . v. fasciata, _donov._--various southern brit, loc., c. round, with thick ribs. . v. ovata, _pennant._--brit. co. generally, c. oval, radiately ribbed. . v. striata, _donov._--_v. gallina_, _v. pennantii_, _v. rugosa_.--brit. co. generally. shores and deep water, c. astarte. . a. triangularis, _mont._--_mactra_ and _goodallia_, _minutissima_ and _triangularis_.--northern parts of britain, to fathoms, c. minute, triangular. . a. elliptica, _brown._--_crassina e._, _crassina ovata_, and _c. sulcata_. scotland, to fath., mud, m. c. oblong, smooth near the margin. . a. sulcata, _costa._--(_pectunculus_) _v. scotica_ and _damnoniensis_, _crassina sulcata_, etc.--devon, cornwall, bantry, etc., c. thickly ribbed. . a. compressa, _mont._--(_venus_) _venus and crassina montagui_, _cyprina comp._--scarborough, northumbria, bantry bay, firth of forth, to fath., m. c. . a. crebricostata, _forbes._--zetland and skye (dead), r. ribs more numerous than in _a. sulcata_. . a. arctica, _gray._--(_crassina_) _venus borealis_, _astarte compressa_.--aberdeen, zetland, st. andrew's bay, etc., rr. lenticular, not ribbed. cytherea. . c. chione, _linn._--(_venus._)--plymouth, s. devon, falmouth, carnarvon, to fath., mr. [illustration: british shells. plate v.] plate v. cyprina. fig. . c. islandica, _linn._ (_venus._)--_c. vulgaris_, _v. mercenaria_.--brit. co. generally, most abundant north, to fath. oval, with thick epidermis. circe. . c. minima, _mont._ (_venus._)--gen. _cyprina_ and _cytherea triangularis_, _apicialis_, _cyrillii_, _minuta_.--guernsey, cornwall, milford haven, clyde, bantry bay, etc., to fath., c. isocardia. . i. cor, _linn._ (_chama._)--_i. hibernica_, _cardita cor._--dublin, skye, etc., mc. heart-shaped, beaks coiled. cardium, or _cockle_. . c. pygmÆum, _donovan._--_c. exiguum._--herne, sark, weymouth, zetland, bantry bay, to fath., mc. hinder side large, angular. . c. papillosum, _poli._--guernsey, st. martin's port, _jeffreys_, r. rather rounded, equally ribbed and grained. . c. punctatum, _broc._, c. nodosum, _turt._--_c. scabrum_, ph.--exmouth, falmouth, galloway, etc., mc. angular behind. . c. fasciatum, _mont._--_c. elongatum_, _c. ovale_, _c. parvum_, _c. rubrum_ (young).--various brit. loc., mr. . c. suecicum, _loven._--_c. swediense_, reeve, _c. loveni_, thompson.--down, oban, zetland, to fath., rr. oval, equally ribbed. . c. aculeatum, _linn._--_c. ciliare_ and _parvum_ (young).--s. devon, mc. thin, oblique, with thorn-like tubercles; interstices of ribs smooth. . c. rusticum, _linn._--_c. tuberculatum_, linn.?--paignton, torbay, velvet strand, dublin co., mc. thick, not oblique, coarsely wrinkled. . c. echinatum, _linn._--_c. mucronatum_, _c. spinosum_.--brit. co. generally, mud and sand, to fath. oblique, wrinkled; hinder tubercles sharp. . c. edule, _linn._--_c. vulgare_, _c. zonatum_, _c. obliquum_, _c. crenulatum_, _c. rusticum_.--brit. co. generally. common eatable, cockle. . c. norvegicum, _spengler._--_c. lævigatum_, _c. serratum_, _c. oblongum_, _c. pennantii_.--brit. co. generally. sand and gravel, to fath. smooth, variegated when young. lucina. . l. divaricata, _linn._ (_tellina._)--_cardium arcuatum_, _l. arcuata_, _commutata_.--near falmouth, fath., rr. rounded, with diverging ribs. . l. flexuosa, _mont._ (_tellina._)--_venus sinuosa_, _amphidesma flexuosa_, _l. sinuata_; gen. _cryptodon_, _axinus_, and _ptychina_.--clyde, bantry, anglesea, etc., to fath., mc. thin, with a fold behind. . l. borealis, _linn._ (_venus._)--_tellina radula_, _lucina r._, _l. alba_.--many brit. loc., to fath., c. lenticular, concentrically laminated. . l. leucoma, _turt._--_l. lactea_, not linn., _loripes lactea_.--torbay, scarborough, bantry bay, etc., low-water to fath., c. round, smooth. . l. spinifera, _mont._ (_venus._)--_myrtea s._, _l. hiatelloides_.--dartmouth, plymouth, hebrides, etc., to fath., m. r. oval; dorsal margin spinose. diplodonta, _mont._ . t. rotundata, _mont._ (_tellina._)--_t. undata_, _lucina r._, _d. dilatata_.--dorset, devon, tenby, bantry bay, etc., to fath., r. clausina, _jeffreys._ . c. ferruginosa, _forbes_, (_kellia._)--skye, loch fyne, etc., to fath., c. concentrically ribbed, minute, oval. . c. croulinensis, _jeffreys._--croulin island, shellands, r. suborbicular. . c. abysslicola, _jeffreys._--not ribbed, r. [illustration: british shells. plate vi.] plate vi. montacuta. fig. . m. ferruginosa, _mont._ (_mya._)--_m. oblonga_, _m. glabra_, _tellimya elliptica_, _erycina f._--s. devon, scarborough, tenby, cape clear, etc., mr. wedge-shaped, long. . m. bidentata, _mont._ (_mya._)--_erycina_, _petricola_, and _tellimya b._--newcastle, weymouth, dublin, etc. burrows in dead shells, mr. short, subquadrate. . m. substriata, _mont._ (_mya._)--_erycina_ and _tellimya s._--devon, tenby, durham, zetland, bantry bay, etc., on spines of _spatangus_, deep water, c. minute, with diverging striæ. turtonia. . t. minuta, _o. fabr._ (_venus._)--_mya purpurea_, etc.--scarborough, tenby, cork, oban, etc., c. kellia. . k. suborbicularis, _mont._ (_mya._)--_bornia inflata_, _tellina_ and _tellimya s._--anglesea, portland, zetland, etc., low-water to fath., mr. . k. lactea, _brown_, (_tellimya._)--brit. co. generally. more oblong than _k. sub._ , . k. rubra, _mont._ (_cardium._)--_poronia r._, etc.--numerous localities; littoral, c. lepton. . l. squamosum, _mont._--_solen_ and _lutraria s._--salcombe bay, tenby, cork, etc., r. flat, subquadrate. . l. nitidum, _turt._ (_kellia._)--torbay, skye, r. less square and flat than _l. squamosum_. . l. convexum, _alder._--bantry bay, rr. convex, granulated. . l. clarkiÆ, _clark._--exmouth, plymouth, zetland, rr. minute, oval, smooth. . l. sulcatulum, _jeffr._--annals, feb. . guernsey, mc. concentrically wrinkled. galeomma. adheres to rocks by byssus. , . g. turtoni, _sowb._--channel islands, and exmouth. oblong, gaping. cyclas. inhabits fresh-water. . c. cornea, _linn._ (_tellina._)--_sphærium c._, scopoli, _c. rivalis_, etc.--ponds and ditches everywhere. equilateral, subquadrate. . c. pisidioides, _gray._--_c. cornea_, var., brit. moll.--ditches and ponds, c. oblique, and light coloured. . c. rivicola, _leach._--_cardium nux_, etc.--thames, etc. large, oval, wrinkled. . c. caliculata, _drap._-_c. lacustris_, etc.--newcastle, bristol, etc., mr. with a ridge at the apex. . c. lacustris, _drap._--_pallida_, gray.--regent's park, etc., mr. oval, light. pisidium. inhabits fresh-water. . p. obtusale, _pfeiffer._--_p. pusillum_, var.? . p. pusillum, _turton_, (_tellina._)--_cyclas fontinalis_ and _gibba_.--in marshes and ponds at various places, c. includes _p. obtustale_? . p. amnicum, _müller_, (_tellina._)--_t. rivalis_, _cyclas palustris_, _c. obliqua_.--british rivers, etc., generally. _c. obliqua_ ribbed. . p. nitidum, _jennyns._--battersea, swansea, etc., c. thick, dark, blunt. . p. henslowianum, _sheppard_, (_tellina._)--_cyclas appendiculata_, _p. acutum_.--cambridge, swansea, etc., r. with a projection on the umbones. . p. pulchellum, _jennyns._--_cyclas fontinalis_, etc.--various localities, c. ridged. . p. cinereum, _alder._--_cyclas c._--various localities, mc. smooth. . p. roseum, _scholtz._--various loc., with _p. pulchellum_ and _p. nitidum_ m. c. subquadrate; animal pink. [illustration: british shells. plate vii.] plate vii. unio. fresh-water mussel with hinge-teeth. fig. . u. margaritiferus, _linn._ (_mya._)--_alasmodon m._, _a. arcuata_, _u. elongata_, _u. sinuata_.--r. conway; rivers in cumberland, wales, ireland, etc., mc. long, thick, arched. . u. pictorum, _linn._ (_mya._)--_u. ovalis_, _u. rostrata_, _u. limosus_, _u. deshayesii_, etc.--various british rivers, c. long, oval, not wedge-shaped behind. . u. tumidus, _retz._--_mya_ and _unio ovalis_, _m. depressa_, _m. ovata_, _myscei o._, _m. solida_.--thames, and various british rivers, c. more solid, deep, and wedge-shaped than _u. pictorum_. anodonta. fresh-water mussel, without teeth. . a. cygnea, _linn._ (_mytilus._)--_m. anatinus_, _m. stagnalis_, _m. paludosa_, _symphonota cy._--britain and europe generally, in rivers and canals, c. dreissina, _beneden._ . d. polymorpha, _pallas_, (_mytilus._)--london docks, edinburgh canal, c. modiola, _lamarck._ . m. modiolus, _linn._ (_mytilus._)--_m. umbilicatus_, _m. curtus_, _m. vulgaris_.--british coasts generally, c. large, brown, not rayed. . m. ovalis?, _sowb._--_m. tulipa_ (_radiata_), var., brit. moll., now named provisionally. less tumid, and with longer and more gradually sloped dorsal line than _m. radiata_, rr. . m. radiata, _hanley_, _brit. marine conch._--_m. tulipa_, brit. moll., mc. tumid, radiated. . m. barbata, _linn._ (_mytilus._)--_m. gibbsii._--jersey, torbay, milford haven, youghal, r. as brit. barbs of epidermis serrated. . m. phaseolina, _philippi._--guernsey, falmouth, scotland, mc. small barbs of epidermis not serrated. . m. cuprea, _jeffreys_, _ann. nat. hist. jan. _.--in the stomach of a bird shot at scarborough, rr. minute, rhomboidal, smooth. crenella, _brown._ . c. nigra, _gray_, (_modiola._)--_mytilus_ and _modiola discrepans_, _depressa_, _compressa_, _discors_.--scotland, r. broad and compressed behind. . c. discors, _linn._ (_mytilus._)--_modiola d._ and _discrepans_.--brit. co. generally, among seaweeds, c. wedge-shaped and lobed. . c. marmorata, _forbes._--_mytilus_ and _mediola discors_, _discrepans_, and _tumida_.--brit. co. generally, cc. rhomboidal, marbled. . c. costulata, _risso._--exmouth, cornwall, swansea, herm. wedge-shaped, marbled, strongly-ribbed. . c. rhombea, _berkley_, (_modiola._)--_m. prideauxiana._--guernsey, torbay, penzance, etc.; coralline, r. . c. decussata, _montagu_, (_mytilus._)--_c._ and _modiola elliptica_, _cicercula_, and _faba_.--scarborough, and a few northern localities, to fath., mc.; norway, etc. subquadrate, decussated, minute. mytilus, _linn._ . m. edulis, _linn._--_m. vulgaris._--brit. co. generally, cc. byssal margin swelled. . m. ungulatus, _linn. syst. nat._--_m. edulis_, var. _m. incurvatus_ (hoof-mussel).--cornwall, guernsey, etc., mr. byssal margin bent inwards, lower margin broad and straight. , . m. galloprovincialis, _lamk._--_m. edulis_, var. _m. dilatatus_?, _m. pellucidus_? (young, f. ), _m. subsaxatilis_?--british channel, etc., c. dorsal margin dilated, beak advancing. [illustration: british shells. plate viii.] plate viii. nucula, _linn._ fig. . n. nucleus, _linn._ (_arca._)--_n. margaritacea_, _glycimeris argentea_.--brit. co. generally, to fath., c. thick, obtuse; beaks terminal. . n. decussata, _sowerby._--_n. sulcata_, _n. polii_.--hebrides, loch fyne, dublin bay, to fath., mr. large, striated; beak not terminal. . n. radiata, _hanley._--_n._ and _arca nucleus_ and _radiata_.--torbay, milford haven, arran, etc., to fath., mc. prolonged anteriorly, rayed. . n. nitida, _sowerby._--_n. nucleus_, var.--numerous british loc., to fath., c. shining, ends rather pointed. . n. tenuis, _montagu_, (_arca._)--north british co., to fath., sand, c. thin, inner edge not crenated; beak terminal. leda, _schum._ beaked behind. . l. caudata, _donovan_, (_arca._)--_arca_ and _nucula minuta_ and _rostrata_.--north co., c.; south co., r. fath. to deep water. ridged. . l. pygmÆa, _munster_, (_nucula._)--_n._ and _l. tenuis_, _gibbosa_, and _lenticula_.--skye, hebrides, croulin isl., to fath. minute, smooth. size (omitted) one-fifth of an inch. arca, _linnæus._ , . a. lactea, _linn._--_a. barbata_, _a. modiolus_, _a. crinita_, _a. perforans_, _a. gaimardii_, var. f. ; _a. quoyi_, var. f. .--penzance, ilfracombe, bantry bay, guernsey, etc. adhering to shells and stones, to fath., c. beaks approaching, radiately striated. . a. tetragona, _poli._--_a. noæ_ and _imbricata_.--many brit, loc., c. ( to fath.). broad area between beaks. . a. raridentata, _s. wood._--_a. pectunculoides._--skye, hebrides, etc., scot. cape clear, to fath., mr. minute, teeth few. . a. nodulosa, _ph._--e. zetland, shetland isls., rr. pectunculus. . p. glycimeris, _linn._ (_arca._)--_a._ and _p._ and _glycimeris pilosa_, _orbicularis_, _undata_, and _marmorata_.--brit. co. generally, to fath., c. limopsis. . l. pellucida, _jeffreys_, _ann. nat. hist. jan. _.--dredged in sand at guernsey, rr. avicula. . a. tarentina, _lamk._--_mytilus_ and _avicula hirundo_, etc.--bantry bay, devon, etc., r. pinna. . p. pectinata, _linn._--_p. fragilis_, _muricata_, _ingens_, _lævis_, _papyracea_, _rotundata_, _elegans_.--dorset, milford haven, hebrides, cape clear; deep water, mc. ostrea. . o. edulis, _linn._--_o. vulgare_, etc.--various natural and artificial beds, in england, scotland, and ireland. the common oyster. anomia. . a. ephippium, _linn._--_a. electrica_, _a. squamula_, _cepa_, etc.--brit. co. generally, to fath., c. pearly and irregular; beak marginal, curved. . a. aculeata, _müller._--_a. striolata._--brit. co. generally, mc. small, with spinous sculpture. . a. striata, _lovén._--hebrides, r. rayed, striated, with apex not marginal. . a. patelliformis, _linn._--_a. undulata._--cape clear, etc., to fath., mr. flat, ribbed. lima. . l. subauriculata, _montagu_, (_pecten._)--_l. nivea_, _sulcata_, etc.--plymouth, man, zetland, belfast, etc., mr. nearly straight. . l. hians, _gmel._ (_vitræa._)--_l. tenera_, _fragilis_, _aperta_, etc.--channel isls., penzance, oban, belfast, etc., mc. oblique, gaping at sides. . l. loscombii, _sowerby._--_pecten_ and _ostrea_ and _lima fragilis_ and _bullata_.--many brit. loc., to fath., mc. oblique, closed at sides. [illustration: british shells. plate ix.] plate ix. pecten. free, except . fig. . p. pusio, _pennant_, (_ostrea._)--_p._, _o._, and _hinnites distortus_ and _sinuosus_.--brit. co. generally, to fath., c. irregular, attached to stones, etc. , . p. varius, _linn._ (_ostrea._)--_p. monotis._--brit. co. generally, to fath.; c. vertically elongate; auricles very unequal. . p. niveus, _macgillivray._--scotland, r. ( fath.) ribs more numerous than _p. varius_; white. , , . p. opercularis, _linn._ (_ostrea._)--_o._, and _p. subrufus_, _pictus_, _lineatus_ (var. f. ), and _sanguinea_.--brit. co. generally, to fath., c. as broad as long; ribs rounded. . p. audouinii, _payraudeau._--_p. opercularis_, var., b. moll.--ribs angular and squamose. , . p. danicus, _chemn._--_p._ and _o. pes-felis_, _glaber_, _triradiata_, _adspersus_, _septemradiata_, etc.--several scotch localities, to fath., mc. very variable, extreme vars. f. , . auricles more equal than _p. tigrinus_. , . p. tigrinus, _müller._--_p. obsoletus_, _domesticus_, _lævis_, _parvus_, etc.--brit. co. generally, to fath., c. variable; one auricle minute, the other large and ribbed. . p. maximus, _linn._ (_ostrea._)--_p. vulgaris._--brit. co. generally, to fath. the common eatable scallop. valves unequal. . p. similis, _laskey._--_o._ and _p. tumidus_.--fr. forth, isl. man, lerwick, cape clear, etc., mc. minute, smooth, with undulating marks. . p. striatus, _müller._--_p. aculeatus_, _fuci_, etc.--scotland, c.; england, r. . p. furtivus, _lovén._--zetland, guernsey, etc., to fath., mr. more rounded, and with auricles less broadly based than _p. striatus_. hippothyris. fixed by byssus. . h. psittacea, _gmel._ (_anomia._)--_a. rostrum-psittaci_, chem.; _terebratula psittacea_.--northumberland, fr. forth; deep water, rr. as brit. "the parrot's-beak anomia." terebratula. fixed by byssus. . t. cranium, _müller._--_anomia c._, and _t. vitrea_.--zetland; deep water, unique as brit. smooth, oval. . t. capsula, _jeffreys_, _ann. nat. hist._, _jan. _.--belfast bay, r. minute, punctured. argiope, or megathyris. . t. caput-serpentis, _linn._ (_anomia._)--_a._ and _t. retusa_, _pubescens_, _costata_, and _aurita_.--oban, skye, etc., to fath., mr. . a. cistellula, _s. wood._ (_terebratula._)--_a. seminulum_?, t. . a. decollata, _chemn._--_a. detruncata._--guernsey, r. . a. seminulum, _philippi._--croulin, near skye, _jeffreys_. crania. . c. anomala, _müller._ (_patella._)--_pat. anomia_, _discina_, and _criopus distorta_, _ostreoides_, _personata_, and _rostrata_.--zetland, arran, lerwick, cork, mr. [illustration: british shells. plate x.] plate x. hyalÆa. _fam._ pteropoda. fig. . h. trispinosa, _lesueur._--once taken on floating timber, dublin. doubtful as british. spirialis, or peracle. _fam._ pteropoda. . s. flemingii, _forbes._--_fusus retroversus_, fl.--zetland, skye, arran, donegal, m. c. snail-shaped. . s. macandrei, _f. and h._--near mizen head, s. ire., rr. turreted. . s. jeffreysii, _f. and h._--brit. channel, rr. discoid. chiton. sedentary on rocks. . c. fascicularis, _linn._--brit co. generally, mc. tufted margin, small, granules large. . c. gracilis, _jeffr._ _ann. nat. hist._, _jan. _.--weymouth. narrow; granules very small; two postero-terminal tufts. . c. discrepans, _brown._--_crinitus_, pennant?--tenby, guernsey, c. tufted margin, large: granules very small. . c. hanleyi, _bean._--scarborough, skye, w. ireland, r. spinose margin. , . c. marmoreus, _o. fabr._--_c. latus_, lowe, _c. lævigatus_, _ruber_, and _pictus_.--scarborough, forth, skye, zetland, w. ire., r. margin smooth. . c. lÆvis, _pennant._--_c. marginatus_, pult., _c. achatina_, brown.--dorset, devon; brit. co. generally, but rare. dorsally elevated; margin reticulated. . c. ruber, _linn._--brit, seas generally, mr. valves smooth; margin coriaceous. . c. cinereus, _linn._--_c. marginatus_, penn.?--brit. co. generally, c. valves carinated; margin and valves granulated. . c. albus, _linn._--_c. asselloides_, lowe.--northern coasts, r. marginal granules scaly and large; dorsal gr. smaller than _c. cinereus_. , . c. asselus, _chemn._--_c. minimus_, _cinereus albus_.--brit. co. generally, c. broad, granules on valves beaded. . c. cancellatus, _sowerby._--_c. albus_, pult.--devon, guernsey, isl. man, oban, zetland, loch carron, r. narrow, back elevated, else like _c. assellus_. patella. (limpet.) sedentary. . p. vulgata, _linn._--brit, generally, cc. ribs not toothed. . p. athletica, _bean._--devon, northumberland, etc., cc. ribs toothed. . p. pellucida, _linn._--_p. lævis_, _cærulea_, _acmæa pel_.--british co. generally, c. smooth. . ---- var. _lævis_, penn. acmÆa, or lottia. . a. testudinalis, _müller._--_p. clealandi._--north ire., c. oval, with tortoise-shell markings. . a. virginea, _müller._--_p. parva_, _pulchella_.--brit. co. generally, mc. pale, pink-rayed, shallow. pilidium, or tectura. . p. fulvum, _müller._--_p. forbesii._--clyde, cork, zetland, etc., r. propilidium. . p. ancyloide, _forbes._--lamlash, ayrshire, etc., r. dentalium, _linn._ . d. entalis, _linn._--brit. co. generally, c. smooth, small end notched. . d. tarentinum, _lamk._--_d. vulgare_, _striatum_, _labiatum_, _politum_, _læve_.--south coasts, c. striated and entire at small end. pileopsis, or capulus. . p. hungaricus, _linn._--fool's-cap limpet.--s. devon, and br. co. generally, c. calyptrÆa, _linn._ . c. sinensis, _linn._ (_patella._)--_c. chinensis_, _albida_, _lævigata_.--s. brit., and chan. isls., r. with oblique septum. [illustration: british shells. plate xi.] plate xi. fissurella. fig. . f. reticulata, _donov._ (_patella._)--_p._ and _f. græca_, _apertura_ (young), _cancellata_, _europæa_.--hebrides, thanet, devon, ireland. on shells, etc., to fath., c. . f. costaria, _deshayes._--guernsey, r. more fine and numerous ribs than _f. reticulata_. puncturella. . p. noachina, _linn._ (_patella._)--_cemoria flemingii_, _fissurella n._, _rimula flemingii_, etc.--scotland and northumberland, to fath., r. with slit under apex. emarginula. . e. reticulata, _sowerby._--_patella fissura_, etc.--brit. co. generally, c. conical, with slit in margin. . e. rosea, _bell._--_e. pileolus_, _conica_, _capuliformis_, etc.--channel isls., exmouth, cornwall, etc., to fath., mc. curved, coarsely cancellated. red within. . e. crassa, _sowerby._--loch fyne, oban and belfast, to fath., rr. large, not cancellated. haliotis, or "ear-shell." . h. tuberculata, _leim._--_h. vulgaris_, channel isls., cc. trochus. . t. zizyphinus, _linn._-_-c. conulus_, _c. discrepans_, _c. lyonsii_ (white, ribbed var.), etc. brit. co. generally, low-water to fath., c. . t. conulus, _linn._--lincolnshire, rr. more simply conical than the most extreme forms of _t. zizyphinus_. . t. alabastrum, _beck._--_t. formosus_.--zetland, lerwick, etc., to fath., r. white, with deep, plain, and beaded ridges. . t. millegranus, _philippi._--_t. clealandi_, _t. martini_.--brit. co. generally, to fath., mr. granulated, whorls with prominent margin. . t. granulatus, _born._--_t. papillosus_, _t. fragilis_.--channel isls., weymouth, dublin, etc., r. like , but grained. . t. striatus, _linn._--_t. parvus_, etc.--s. brit., c. more finely ribbed than _t. exiguus_. . t. exiguus, _pult._--_t. exasperatus_, _minutus_, etc. s. co., c. . t. montagui, _gray._--_t. striatus_, forbes.--scarborough, exmouth, cape clear, etc., c. elevated, whorls tumid. . t. tumidus, _mont._--_t. patholatus_, _rackettii_, etc. brit. co. generally, c. short, whorls tumid, umbilicated. . t. cinereus, _linn._--_t. lineatus_, _t. perforatus_, etc.--brit. co. generally, c. littoral, small umbilicus. . t. umbilicatus, _mont._--_t. cinerarius_, etc.--guernsey, s. and w. brit. co., c. littoral, umbilicus large. . t. majus, _linn._--_t. tuberculatus._--brit. co. generally; littoral, c. broad, tuberculated. large umbilicus. . t. lineatus, _costa._--_t. crassus_, etc.--channel isls., devon. w. ire., mc. smooth, imperforate. margarita, or trochus. . m. undulatus, _sowerby._--_turbo carneus_, _m. striata_, etc.--scotland, to fath., mc. striated and undulated. . m. helicinus, _fabricius._--_turbo_ and _trochus neritoideus_, _margarita_, _m. vulgaris_, etc.--many brit. loc.; littoral, c. . m. pusillus, _jeffreys._--lerwick, r., to fath. minute, white, depressed. . m. exilis, _phil._--_skenea cutleriana._--guernsey, skye, etc., r. globose, striated. adeorbis. . a. subcarinata, _mont._--(_helix_) _trochus rugosus_, _cingula subc._, etc.--s. brit, co., mr. depressed, keeled. scissurella. . s. crispata, _flem._--zetland, etc., in sand, mc. phasianella. . p. pullus, _linn._ (_turbo._)--_t. pictus_, _cingula p._, etc.--brit. co. generally, c. [illustration: british shells. plate xii.] plate xii. ianthina. floats on ocean. fig. . i. communis, _lamk._--_helix ianthina_, _i. fragilis_, etc.--cornwall, bristol, etc.; oceanic, c. sides depressed. . i. britannica, _leech._ _reeve._--ireland, cornwall, etc., mr. darkly coloured, not compressed. . i. pallida, _harvey._--_i. patula._--clare, rr. as brit. . i. exigua, _lamk._--cornwall, clare, etc., mr. neritina. in rivers. . n. fluviatilis, _linn._--_n. fontinalis._--thames, trent, humber, etc., scotch lakes, cc. bithinia. in ponds. . b. leachii, _shepp._ (_turbo._)--_b. ventricosus_, _paludina acuta_, _similis_, etc.--rivers s. brit., mr. narrow, with rounded whorls. . b. tentaculata, _linn._ (_helix._)--_t. nucleus_, _paludina impura_, etc.--fresh-water, throughout brit. oval. paludina. in ponds. . p. listeri, _forbes and hanley._--_helix vivipara_, etc.--lakes and ponds generally, mc. whorls more separate, umbilicus larger than _p. vivipara_. . p. vivipara, _linn._--_pal. achatina_, etc.--thames, etc., c. valvata. in ponds. . v. piscinalis, _müller._--_nerita_, _turbo_, _cyclostoma fontinalis_, _obtusa_, _thermalis_, etc.--fresh-water, c. subglobose. . v. cristata, _müller._--_v. planorbis_, etc.--many loc., mc. orbicular. littorina. on the sea-shore. , . l. rudis, _donov._ (_turbo._)--_l. littoreus_, etc., _l. nigro-lineatus_ (var. f. ).--british shores generally, cc. , . l. littorea, _linn._ (_turbo._)--_l. vulgaris_, etc.--british shores generally. the common eatable winkle. , . l. tenebrosa, _mont._ (_turbo_).--british shores generally, c. not thickened at bottom of mouth like _l. rudis_. . l. patula, _jeffreys._--_l. labiata_, _l. jugosa_, etc.--common on our shores. . l. saxatilis, _johnston._--_l. neglecta._--probably _l. patula_ var.? , . l. littoralis, _linn._ (_turbo._)--_t. neritoides_, _t. ustulatus_, etc,--brit. co. generally. depressed above. . l. fabalis, _turt._--_l. beanii._--young of _l. littoralis_? . l. neritoides, _linn._ (_turbo._)--_t. petræa_, _l. cærulea_, etc.--kent, sussex, etc., c. with white band. . l. palliata, _say_, (_turbo._)--yarmouth, mr. lacuna. , . l. puteolus, _turt._ (_turbo._)--_cochlea_, _helix_, and _nerita parva_, _fasciata_, _lacuna_, _rufa_, etc.--brit. shores, c. globose. , . l. vincta, _mont._ (_turbo._)--_t. canalis_, _quadrifasciatus_, etc,--brit. co. generally, c. . l. crassior, _mont._ (_turbo._)--_l. pallidus._--numerous brit. co. thick, conical. . ---- var. ? of this rather than of _c. vincta_. . l. pallidula, _costa_, (_turbo._)--brit. co. generally, c. . l. patula.--fry of _l. pallidula_? [illustration: british shells. plate xiii.] plate xiii. assiminea. fig. . a. grayana, _jeffreys._--_limneus_ and _paludina g._--greenwich and other marshes. . a. littorea, _delle chiaje_, (_helix littorina._)--_rissoa globularis_ and _littorea_.--on shore at weymouth, serk, portland, mr. rissoa, or cingula. . r. ulvÆ, _pennant_, (_turbo._)--_helix_, _cingula_, _paludina_, and _littorina_.--in brackish water, on british shores, c. *. ---- var. _subumbilicata_, r. . r. barleei, _jeffreys._--_r. ulvæ_ var.--loch carron, skye, r. . r. striatula, _mont._--_r._, _turbo_, _cingula_, and _littorina carinata_ and _monilis_.--devon, margate, galway, herm, etc., to fath., mr.; s. eu. carinated. . r. cimicoides, _forbes._--_r. sculpta._--w. scotland. like _r. zetlandica_, but with outer lip crenulated; finely decussated. . r. zetlandica, _mont._ (_turbo._)--_r._, _cyclostoma_, _cingula scalariformis_, _cyclostrema z._--n. scotland, to fath., mc. whorls angulated. . r. crenulata, _michaud._--_turbo_ and _r. cimex_ and _cancellatus_.--falmouth, cornwall, skye, galway, c. very coarsely cancellated. . r. calathus.--_forbes and hanley._--sheerness, whitesand bay, to fath., r. finely cancellated. . r. beanii, _hanley._--cornwall, plymouth, orkney, galway, c.; n. eu. striated. . r. abyssicola, _forbes._--n. scotland; deep water, r. . r. lactea, _michaud._--_turbo cancellatus._--jersey and medit., rr. oval, plicated and striated. . r. punctura, _montagu._--_turbo_ and _cingula_ and _r. reticulata_.--brit. co. generally, to fath. . r. costata, _adams._--_r._, _turbo_, _cingula plicata_, _costata_, and _exigua_.--south co. brit., s. wales, orkneys, ireland, channel isls., to fath., c. . r. striata, _mont._--_r._, _turbo_, and _cingula semicostata_, _minutissima_, _communis_, _gracilis_, etc.--brit. co. generally, n. and s. eu.; littoral c. , , . r. parva, _costa._--_t._, _c._, and _r. sublutea_, _lactea_, _alba_, etc., _r. interrupta_ (var. f. ), _r. sarsii_, var. f. (unique).--brit. shores generally, c. . r. costulata, _alder._--_turbo variabilis_, _r. similis_.--devon, channel isls., w. ireland, etc., c.; s. eu. . r. rufilabrum, _leach._--_r._ and _c. hyalina_ and _punctata_.--devon, belfast, etc., mc. . r. labiosa, _mont._ (_helix._)--_t._, _c._, and _r. membranacea_ and _costata_.--brit. co. generally, c. , , , r. inconspicua, _alder._--_r. albula_ and _supra-costata_, var. f. , _r. similis_, var. , _r. maculata_.--brit. co. generally, c. . r. semistriata, _mont._--_t._ and _r. pulchra_ and _tristriata_.--brit. shores generally, c. . r. cingillus, _mont._ (_turbo._)--_r._, _t._, and _c. vittata_, var., _r. graphica_ and _r. rupestris_.--brit co. generally. . r. vitrea, _mont._ (_turbo._)--_helix glabrata_, _r. crystallina_.--exmouth, oban, birterbuy, etc., mr. elongated, smooth. . r. proxima, _alder._--a rare irish species. elongated, striated. [illustration: british shells. plate xiv.] plate xiv. rissoa,--_continued_. fig. . r. pulcherrima, _jeffreys._--channel isls., r. . r. soluta, _philippi._--exmouth, bute, cork, etc., r. like _r. pulch._, but with spiral striæ. . r. alderi, _jeffreys_, _annals, aug. _.--skye, rr. larger and more conical than _r. soluta_. . r. fulgida, _adams_, (_helix._)--_turbo_ and _cingula f._--weymouth, arran, cork, etc., mr. whorls rounded and banded. . r. anatina, _drap._ (_cyclostoma._)--_paludina_ and _littorina a._--very rare, greenwich marshes. . r. eximia, _jeffreys._--_chemnitzia barleei_, clark. . r. ventrosa, _mont._ (_turbo._)--_cyclostoma_, _paludina_, and _cingula acutus_, _ventricosus_, _octona_, _stagnorum_, etc.--marine shores and brackish-water marshes, mc. . r. denticulata, _mont._ (_turbo._)--herm, rr. . r. unica, (_turbo._)--_aclis u._, brit. moll., _turritella_, _pyramis_, and _chemnitzia_, r.--devon, cork, etc., mr. . r. glabrata, _jeffreys._--n. sp. . r. castanea, _jeffreys._--n. sp. barleeia. . b. rubra, _flem._ (_cingula._)--_turbo_, _c._, and _rissoa ruber_, _unifasciatus_, _fulva_.--herm, tenby, dunbar, etc., s. eu., mr. jeffreysia. . j. diaphana, _alder_, (_rissoa._)--_r. glabra._--dublin, swansea, northumberland, etc.; littoral, r. . j. opalina, _jeffreys_, (_rissoa._)--channel isls., r. . j. globularis, _jeffreys._--skye. . j. gulsonÆ, _clark_, (_odostomia._)--_chemnitzia g._--sandwith, lerwick, weymouth, etc., guernsey. euomphalus. . e. nitidissimus, _adams_, (_helix._)--_skenea_, b. moll., _truncatella atomus_.--shetland to channel isls., mc. . e. rota, _forbes and hanley_, (_skenea._)--donegal, rare. like a minute ammonite. skenea. . s. planorbis, _o. fabr._ (_helix._)--_turbo_, _sk. depressa_.--brit. shores generally, on coastal corallines, c. flat, like a _planorbis_. . s. divisa, _flem._ (_turbo._)--_helix_ and _sk. serpuloides_, _adeorbis striatus_.--scarborough, weymouth, orkney, galway, etc., to fath., mr. striated. . s. costulata, _möller_, (_margarita._)--loch fyne, rr. . s. lÆvis, _philippi_, (_delphinula._)--newcastle-on-tyne, rr. aclis. . a. ascaris, _turt._ (_turbo._)--_turritella_, _alvania_, and _pyramis supranitida_ and _acutissima_.--ireland, tenby, zetland, mr. . a. supra-nitida, _s. wood_ (_alvania._)--tenby, dublin, etc., rr. . a. nitidissima, _mont._ (_turbo._)--_turritella_, _pyramis_, and _chemnitzia_.--falmouth, burrow isl., r. eulimella. . e. scillÆ, _lovén_, (_turbonilla._)--_eulima_, _odostomia_, _chemnitzia_, and _eulimella crassula_, and _macandræi_.--n. scotland, croulin, etc., to fath., r. . e. acicula, philippi, (_melania._)--_e._, _chemn._, _odost._, and _eulima clavula_.--skye, rr. . e. affinis, _philippi_, (_eulima._)--_pyramis_, _odost._, and _e. gracilis_, _lævis_.--skye, torbay, r. . e. clavula, _lovén_ (_turbonilla._)--_odostomia c._--torbay, rr. guernsey. . e. obeliscus, _jeffreys_, _ann. nat. hist. jan. ._--shetland. [illustration: british shells. plate xv.] plate xv. turritella. fig. . t. cornea, _lamk._--_t. communis_, var., b. m.--cork and zetland, mr. whorls less flat and less rapidly enlarged than _t. communis_. a white var. exists (_t. nivea_). , . t. communis, _risso._--_t. cornea_?, _t. terebra_.--brit. co. generally; to fath., cc. aperture rather square. aporrhais. . a. pes-pelicani, _linn._ (_strombus._)--_a. quadrifidus_, _tritonium_, and _rostellaria p._--brit. co. gen.; n. and s. eu.; to fath., c. outer lip with one anterior lobe. . a. pes-carbonis, _brongniart._--_rostellaria_ and _a. p._, and _serressiana_.--zetland, to fath., r. outer lip with two anterior lobes. cÆcum. . c. trachea, _mont._--_dentalium_ and _orthocera imperforatum_, _c. annulatus_.--devon, weymouth, scotland, cork, etc., r.; s. eu. ringed and striated. . c. glabrum, _mont._--_c._, _dentalium_, and _orthocera minutum_, and _lævissimum_.--exmouth, weymouth, swansea, lerwick, bantry bay. rare, smooth. cerithium. . c. reticulatum, _costa_, (_strombiformis._)--_murex_ and _terebra r._--brit. co. gen., to f., c. narrow, and closely reticulated. . c. metaxa, _delle chiaje._--_c. angustissimum._--guernsey, r.; s. eu. lengthened, white. . c. adversum, _mont._ (_murex._)--_c._, _triphoris_, _turbo_, and _terebra a._, _perversus_, and _reticulatus_.--w. and s. brit., channel isls., etc., to fath., mr. cerithiopsis. . c. tuberculare, _mont._ (_murex._)--_cerithium_ and _terebra t._--brit. co. gen.; s. eu.; to fath., mc. three rows of tubercles in the penultimate whorl. . c. clarkii, _hanley._--exmouth, rr. two rows of tubercles. . c. nivea, _jeffreys_, _ann. nat. hist. _.--in shell sand, belfast, r. rather buccinum-shaped. . c. metula, _lovén_, (_cerithium._)--_c. nitidum_, forbes.--zetland, to fath., r. white, with angular whorls. . c. pulchella, _jeffreys._--falmouth, plymouth, guernsey, r. closely whorled and cancellated. scalaria. . s. communis, _lamk._--_turbo_ and _strombiformis clathrus_ and _clathratus_.--s. co. principally, c. laminarian zone, s. eu. ridges raised; whorls separated. . s. groenlandica, _chemn._ (_turbo._)--_s. planicostata_, _subulata_.--fragments only, n. scotland, n. eu. grooved between ridges. . s. turtonis, _turton._--scarborough, exmouth, cork, etc., n. and s. eu., r. as brit. ridges flat. . s. trevelyana, _leach._--n. brit., to fath., mr. thin, with ribs narrower than _sc. turtonis_. . s. clathratula, _mont._--s. brit. and channel isls., mr. small, white, with thin ribs. stylifer. . s. turtoni, _brod._--_phasianella stylifera_, _velutina s._, _s. globosus_ and _astericola_.--on spines of _echinus sphæra_, torbay and berwick, r. glassy, thin. eulima. . e. polita, _linn._ (_helix._)--_strombiformis_, _turbo_, _rissoa_, and _phasianella p._ and _albus_, _boscii_ and _anglica_.--ireland, s. brit., e. scot., n. and s. eu., to fath., mr. rather solid. . e. distorta, _deshayes._--brit. co. gen., mc.; to fath.; n. and s. eu. small, tortuous. . e. stenostoma, _jeffreys_, _ann. nat. hist. ._--zetland and norway, rr. thin, with rapidly increasing whorls. . e. subulata, _donov._ (_turbo._)--_strombiformis_, _helix_, and _melania s._ and _glaber_, _trifasciatus_, _donovani_, and _lineata_.--s. and w. brit., ire., zetland, medit., to fath., mr. whorls deep, banded. . e. bilineata, _alder._--or _e. subulata_, var.--northumberland, etc. whorls more swelled than _e. su._, two-banded. [illustration: british shells. plate xvi.] plate xvi. chemnitzia. fig. . c. elegantissima, _mont._ (_turbo._)--_t. lacteus_, linn.?, _t. acutus._--brit. co. generally; not deep, c. interstices of longitudinal ribs smooth. . c. simillimus, _mont._ (_turbo._)--_c. gracilis_, phil. more slender and minute than f. . . c. pusilla, _phil. moll. sic._ . _p._ . _pl._ . _f._ .--more stout than f. , with the ribs straight and broad. medit., brit.? , . c. rufa, _phil._--and var. _c. fulvocincta_ (f. ).--brit. co. generally, to fath., mc. spiral grooves between ribs. . c. formosa, _jeffreys_, (_odostomia._)--swansea, shellness, bantry bay, etc., mr. grooved between ribs, excavated at suture. . c. fenestrata, _forbes and jeffr._ (_odostomia._)--torbay, etc., r. with pits between spiral ridges. . c. rufescens, _forbes._--_odostomia_ and _turritella indistincta_ and _scalaris_.--clyde, hebrides, oban, to fath., r. more stout than _c. rufa_. three-banded. . c. scalaris, _philippi_, (_melania._)--exmouth, guernsey, medit., r. ribbed; whorls angular above. . c. clathrata, _jeffreys._--birterbuy bay, r. lower part of whorls spirally grooved between ribs. . c. indistincta, _mont._ (_turbo._)--_odost._, _turritella_, _terebra_, and _pyramis truncata_ and _speciosa_, etc.--brit. co. generally, to fath., mr.; s. eu. ribs curved, striated between. truncatella. . t. subcylindrica, _linn._ (_helix._)--_t. montagui_, _turbo truncatus_, _subtruncatus_, _cyclostoma truncatulum_, _turritella t._ and _s._, etc.--weymouth, s. devon, scarborough, etc., c. natica. . n. helicoides, _johnston._--scotland, scarborough, etc., to fath., r.; n. eu. thin-grooved suture. . n. montagui, _forbes._--_nerita rufa_, _natica r._ and _rutilla_.--principally northern loc. in sand and gravel, to fath., mr. small, stout. . n. kingii, _forbes and hanley._--northumberland, unique, _jeffreys_ coll. . n. nitida, _donovan._--_nerita_ and _natica catena_, _nitida_, _alderi_, _glaucina_, etc.--brit. co. generally, to fath., c. oblique, marked with undulating lines. . n. monilifera, _lamk._--_nerita glaucina_, _catena_, etc.--near water-mark, in sandy places generally, c. whorls rounded. . n. sordida, _phil._--_n. fulva_, _plumbea_, etc.--scilly, cape clear, zetland, etc., to fath., r. . n. pusilla, _say._--_n. groenlandica_, _livida_, _alba_.--northumberland, yorkshire, n. eu., fath., r. white; umbilicus small. recluzia. . r. aperta, _jeffreys._--_natica aperta_, lovén?--zetland, rr. velutina. . n. lÆvigata, _linn._ (_helix._)--_bulla_, _velutina_, etc.--brit. co. generally, to fath., n. eu., c. . n. flexilis, _mont._ (_bulla._)--_coriocella_ and _sigaretus plicatilis_.--n. scot., fath., rr. lamellaria. . l. perspicua, _linn._--_helix_, _bulla haliotoidea_, _sigareta_ and _coriocella neritoideus_.--brit. co. generally, but r.; to fath., mr. thin, glassy, more ventricose than _l. tentaculata_. . l. tentaculata, _mont._--_sig._ and _cor._--falmouth, swansea, arran, etc. laminarian, mr. upper whorls less full than _l. perspicua_. otina. . o. otis, _turt._ (_helix._)--_velutina_, _galericulum ovatum_.--wales, devon, channel isls., clare, etc., mc. littoral. trichotropis. . t. borealis, _broderip and sowb._--_t._ and _murex carinatus_, _umbilicatus_, _acuminatus_, etc.--n. scotland, w. ireland, to fath., r. [illustration: british shells. plate xvii.] plate xvii. odostomia. fig. . o. unidentata, _mont._ (_turbo._)--_voluta u._, _o. plicata_.--brit. co. generally, mc. rather conical. tooth strong; no epidermis. . o. turrita, _hanley_, _brit. mar. conch._--_o. unidentata_, var. b. m.--r. more lengthened than no. . , . o. acuta, _jeffreys._--torbay, loch fyne, galway, etc., mc. strong, conical. suture deep. . o. plicata, _mont._ (_turbo._)--_voluta p._, _v. plicatula_, _o. annæ_, _jaminia p._, etc., mc.--salcombe, swansea, dublin, aberdeen, mc. turreted. narrow, thin. . o. insculpta, _mont._ (_turbo._)--_voluta_, _jaminia_, and _o. ins._--s. devon, oban, hebrides, etc., r. conical, spirally striated. . o. pallida, _mont._ (_turbo._)--_vol._, _cingula_, _phasianella p._, _o. ambigua_.--s. devon, rr. broad. thin, pillar straight. . o. conoidea, _brock._--_turbo_, _odost._, etc.--n. scotland, mc. s. devon, mr. n. and s. eu. white. whorls straight; throat striated. . o. conspicua, _alder._--isl. man, whitburn, herm. coloured. whorls rounded; throat striated. . o. truncatula, _jeffreys._--plymouth. elongated. . o. cylindrica, _alder._--_turbo nivosus_?--s. devon, ilfracombe, guernsey, cork, r. cylindrical, few whorls. , . o. eulimoides, _hanley._--_o. crassa_, _o. pallida_ (var. f. ), _o. notata._--brit. co. generally. coralline zone, mr. ample body-whorl. . o. dubia, _jeffr._--s. devon, lerwick, guernsey, mr. rather large body-whorl. , . o. alba, _jeffreys_, (and var.)--swansea, skye, zetland, guernsey, mr. thin, whorls rounded. . o. nitida, _alder._--s. devon. littoral, mc. aperture differently formed from no. . . o. lukisii, _jeffreys_, _ann. nat. hist. ._--guernsey. sublittoral and coralline, mc. whorls tumid; a slight umbilicus. . o. glabrata, _muhlfeldt_, (_helix._)--_rissoa punctulum_, etc.--zetland, r. pillar-lip thin, arched. . o. rissoides, _hanley._--_o. scalaris._--channel isls., devon, cornwall, tenby, etc., mc. thin, conical, no umbilicus. . o. albella, _lovén._--_o. rissoides_, var., b. m.--guernsey, s. devon, etc. turreted, upper whorls more cylindrical than no. . . o. obliqua, _alder._--tynemouth, guernsey, fath. to deep water, rr. thin, oblique. . o. diaphana, _jeffr._ _ann. nat. hist. new ser. vol._ ii. _p._ .--r. manifestly distinct from no. . . o. strialata, _alder._--northumberland, rr. conical, striated. . o. minima, _jeffreys_, _ann. nat. hist. jan. , ._ . o. interstincta, _mont._ (_turbo._)--_t._, _o._, _voluta_, and _jaminia canaliculata_, _oblonga_, and _obtusa_.--brit. co. generally. shallow water, c. with longitudinal ribs. . o. dolioliformis, _jeffr._--scarborough, exmouth, swansea, tenby, rr., scotland. oval, body-whorl very tumid. . o. warrenii, _thompson_, (_rissoa_.)--_turbonilla_ and _o. obliqua_, _o. decorata_.--dublin, s. devon, w. scotland, r. turreted. mouth oblique; an umbilicus; no fold or columella. . o. spirialis, _mont._ (_turbo._)--_voluta_ and _rissoa s._, _pellucida_, and _plicatula_.--brit. co. generally, not deep, mc. whorls ribbed longitudinally above, spirally beneath. . o. decussata, _mont._ (_turbo._)--_t. helix_, _rissoa_ and _o. arenaria_, _pellucida_?, and _d._--exmouth, lerwick, etc., r. ribbed and spirally striated. . o. excavata, _phil._ (_rissoa_.)--_r._, _o._, and _cingula harveyi_ and _deshayesiana_.--dublin, arran, guernsey, r. largely sculptured. [illustration: british shells. plate xviii.] plate xviii. triton. fig. . t. cutaceus, _linn._--channel isls., rr. as brit. mr. lukis's specimen taken living off guernsey. . t. nodiferus, _lamk._--guernsey; three living specimens, one incrusted with _lepralia coccinea_ (truly british). mr. jeffrey's specimen reduced. murex. . m. erinaceus, _linn._--_purpura scalata_, var. _m. tarentinus_.--brit. co. generally; to fath., c. n. and s. eu. . m. corallinus, _scacchi._--_fusus_ and _m. lavatus_, _inconspicuus_, _gyrinus_, and _badius_?--channel isls. and s. eu., c. m. rudis. see _trophon_. purpura. . p. lapillus, _linn._ (_buccinum._)--_b._ and _p. filosum_, _imbricatum_, and _bizonalis_.--in crevices on shores, brit. co. generally, n. and s. eu., c. lachesis. . l. minima, _mont._ (_buccinum_.)--_b. brunneum_, _b. rubrum_, _nesæa granulata_, _mamillata_, _fusus minimus_, etc.--channel isls. and s. brit., on shores. s. eu. buccinum. . b. holbollii.--_mangelia h._--cornwall, rr. . b. undatum, _linn._--_b. striatum_, _anglicanum_, _pyramidale_, _imperiale_, etc.--brit. co. generally, shores, cc. n. eu. and am. . b. acuminatum, _brod._--_b. undatum_ var., b. m.--rr. . b. ciliatum, _fabr._ (_tritonium._)--shetland, deep water, r. more thin than no. ; with striæ finer, and hairs of epidermis tufted minutely. . b. fusiforme, _brod._--cork, wexford, rr. turreted, fusiform, white, ribbed, striated. . b. dalei, _sowerby._--_b. ovum_, _halia flemingiana_.--torbay, northumberland, aberdeen, etc., r. ventricose. . b. humphreysianum, _bennett._--_tritonium h._--cork, skye, bantry bay, r. light, smooth. fusus. . f. berniciensis, _king._--northumberland, rr. carinated, with open pink mouth. . f. norvegicus, _chemn._ (_strombus._)--_tritonium n._--scarborough, durham, rr. oval, smooth, with large aperture. . f. antiquus, _linn._ (_murex._)--_m._, _b._, and _tritonium despectus_, _contrarius_, _carinatus_, _babylonicus_, etc.--various brit. co., to fath., c. . f. islandicus, _chemn._--_murex corneus_, _tritonium gracile_, etc.--brit. co. generally; to fath.; n. eu., c. (see _f. propinquus_.) . f. turtoni, _bean._--yorkshire, northumberland, fath., rr. . f. propinquus, _alder._--_f. corneus_ and _islandicus_, var.--n. scotland, bantry bay, northumberland, deep water, mr. shorter than _f. islandicus_, with deep suture and symmetrical spire. trophon. . t. rudis, _phil._ (_fusus._)--_murex r._, jeffreys.--tenby; unique as british. whorls and ribs rounded. . t. muricatus, _mont._--_fusus_ and _murex m._--brit. co. generally, channel isls., to fath., mr. whorls angular, ribs intersected. . t. scalariformis, _gould._--belfast, in sand, rr. ribs smooth. . t. clathratus, _linn._ (_murex._)--_tritonium_, _fusus_, and _pleurotoma bamfius_.--irish sea, zetland, mc. ribs laminated. . t. barvicensis, _johnston._--_fusus_ and _tritonium b._--hebrides, cork, northumberland, fath., mr. ribs aculeated. [illustration: british shells. plate xix.] plate xix. nassa. fig. . n. reticulata, _linn._ (_buccinum._)--_n. pullus_, _tritonium r._--brit. and eu. co. generally. littoral, cc. . n. incrassata, _müller_, (_buccinum._)--_n._ and _b. minutum_, _macula_, _asperulum_, etc.--brit. shores generally, to fath., gravel, c. . n. pygmÆa, _lamk._ (_ranella._)--_b. tuberculatum_, _tritonia varicosa_, etc.--s. brit. co., s. eu., fath. to deep water, c. small, with white varices on the body. mangelia. . m. turriculata, _mont._ (_murex._)--_bela_, _fusus_, and _pleurotoma angulatus_, etc.--brit. co. generally, to fath., n. eu., c. whorls flat above. . m. trevelliana, _turt._--_pleurotoma_, _bela_, and _m. reticulata_, _decussata_, and _leucostoma_.--northumberland, aberdeen, zetland, etc., to fath., r. whorls with angular slope above. . m. rufa, _mont._ (_murex._)--_f._, _m._, and _b. chordula_, _ulideana_ (var.), etc.--brit. co. generally, mc. . m. teres, _forbes_, (_pleurotoma._)--_p. boreale._--various loc., to fath. s. eu., mr. carinated, aperture deeply notched. . m. purpurea, _mont._ (_murex._)--_fusus_ and _pleu. p._, _philberti versicolor_ and _variegatum_.--brit. co. gen., to fath., c. s. eu. . m. cancellata, _sowerby_ (_fusus._)--_m. purpurea_ var., _f. asperrimus_,--cornwall, cork, r. sharply sculptured. . m. reticulatum, _brown_, (_pleurotoma._)--_m. cancellata_ var.--shetland, guernsey, rr. sculpture between and ; inner lip not thickened. . m. leufroyi, _michaud_, (_pleurotoma._)--_p._, _f._, and _m. inflata_, _boothii_.--arran, orkneys, guernsey, etc.; s. eu., to fath., mc. . m. linearis, _mont._ (_murex._)--_m._, _pl._, _fus. elegans_, _concinna_, etc.--brit. co. generally, sand and shells, to fath., c. . m. scabra, _jeffreys_, (_pleur._)--_m. linearis_ var.--guernsey, plymouth, r. . m. nebula, _mont._ (_murex._)--_m._, _p._, and _f. bertrandi_, _varians_, and _pyramidatus_.--various places and depths, n. and s. eu., c. . m. lÆvigata, _phil._ (_pleu._)--_m. nebula_ var.--south brit., s. eu. small, fusiform, shiny, banded. . m. guinniana, _phil._ (_pleu._)--_m. nebula_ var.--tenby, etc., mr. s. eu. whorls longer than no. . . m. brachystoma, _phil._ (_pleu._)--_m. tiarula_ and _clavatula b._--brit. co. gen., mr. turreted; ribs crossed by raised lines. . m. nana, _lovén_, (_tritonium._)--_fusus albus._--lerwick, zetland, orkneys, etc., fath., and deep, r. ventricose, cancellated. , . m. striolata, _scacchi_, (_pleu._)--_p._ and _murex smithii_, _farranti_.--s. devon, clyde, guernsey, bantry, etc., medit., r. as brit. ribs angularly curved above. , . m. costata, _pennant_, (_murex._)--_buccinum_, _fusus_, _pl. c._, etc.; var. f. , _m. metcalfei_.--brit co. generally, to fath., n. and s. eu., c. body-whorl larger than no. . . m. coarctata, _forbes._--_pl._, _m. costata_ var., b. m.--distribution as and ; not so common. . m. septangularis, _mont._ (_murex._)--_m._, _f._, and _pl. costatus_, _heptagona_, etc.--torbay, bristol channel, forth, galway, to fath., mc. . m. attenuata, _mont._ (_murex._)--_m. aciculatus_, _pl. gracilis_, _villiersii_, etc.--s. devon, oban, hebrides, cork, etc., mr. s. eu. . m. gracilis, _mont._ (_murex_)--_m. emarginatus_, _suturalis_, _elegans_, etc., s. brit., galway, s. eu., mr. m. holbollii. see _buccinum_. erato. . e. lÆvis, _donovan_, (_voluta._)--_e._, _marginella_, _bulla_, _volvaria_, and _columbella fusiformis_, _cypræola_, _donovani_, _muscaria_, etc.--brit. co. generally, to fath., mc. cyprÆa. . c. europÆa, _mont._--_cypr._ and _trivia_, _pediculus arctica_, _bullata_, and _diaphana_.--brit. co. generally, to fath., c. [illustration: british shells. plate xx.] plate xx. tornatella. fig. . t. fasciata, _lamk._--_voluta tornatilis_, linn., _bulimus t._, _t. pellucida_ and _pusilla_ (young).--brit. co. generally. n. and s. eu. ovula. . o. patula, _penn._ (_bulla_).--exmouth, arran, etc., fath. s. eu. wide aperture, mc. . o. acuminata, _brug._--_bulla_ and _volvula a._--loch fyne, lamlash, galway, etc., r. s. eu. narrow, pointed. cylichna. . c. cylindracea, _penn._ (_bulla._)--_bullina_ and _volvaria c._, _oliva_, and _umbilicata_.--brit. co. generally, c. n. and s. eu. . c. obtusa, _montagu_ (_bulla_).--_utriculus_, _b._ and _c. jerviscensis_ and _discors_.--brit. co. generally, c. . c. mamillata, _philippi._--_bulla_ and _tornatina m._ and _truncatula_.--exm., skye, galway, etc., mc. s. eu. spire sunk, apex mamillated. . c. truncata, _adams_, (_bulla._)--_b. truncatula_, _retusa_, _semisulcata_.--brit. co. generally, c. n. and s. eu. . c. nitidula, _lovén._--_c._ and _bulla n._ and _umbilicata_.--skye, loch fyne, etc., r. n. eu. elongated, oval. . c. conulus, _desh._--zetland, rr. conical. . c. strigilla, _lovén._--_c._, _bulla_, and _atys s._ and _ovulata_.--scotland, mr. spirally striated. . c. umbilicata, _mont._ (_bulla_).--_bullina_ and _volvaria u._ and _subcylindrica_.--brit. co. gen., mc. with umbilicated apex. , . c. lajonkaireana, _basterot_, (_bulla._)--guernsey, r. narrower, and with more raised spire than _c. obtusa_. amphispira. . a. hyalina, _turt._ (_bulla._)--_a. diaphana_ and _utriculus pellucidus_, _minutus_, and _candidus_.--scarborough, weymouth, cork, etc. littoral, mc. n. eu. rather square. . a. globosa, _jeffreys_, _ann. nat. hist. jan. ._--skye. akera. . a. bullata, _müller._--_bulla akera_, _b. norvegica_, _b. resiliens_, _fragilis_, _flexilis_, _hanleyi_.--southampton, zetland, galway, etc. littoral, mc. n. and s. eu. bulla. . b. cranchii, _leach._--_b. punctura_ and _striata_.--brit. co. gen. devon, aberdeen, cork, etc., to fath., mr. spirally puncto-striated. . b. cornea, _lamk._--_b. hydatis_ (as of _linn._), _b. navicula_, _b. ampulla_, _haminea hydatis_.--south brit. co., to fath., c. s. eu. broad, thin. . b. hydatis, _linn._--_haminea elegans._--guernsey and mediterranean. narrower and more solid than _b. cornea_. philine. . p. aperta, _linn._--_p. bulla_, _bullæa_, and _lobaria a._, _quadripartita_, _quadrilobata_, and _planciana_.--brit. co. gen., c. s. eu. large, smooth. . p. scabra, _müller._--_bulla_ and _scaphander scabra_, _pectinata_, _dilatata_, and _catenulifera_.--northumberland, zetland, ireland, etc., mc., to fath. n. eu. oblong, serrated. . p. quadrata, _s. wood._--_bullæa_ and _p. scutulum_.--zetland, etc., to fath., r. striated. . p. catena, _mont._--_bulla_ and _bullæa c._, _angustata_, and _punctata_,--brit. co. generally, mr., to fath. with chain-like sculpture. . p. punctata, _clark._--_bulla_ and _bullæa_.--devon, swansea, aberdeen, clare. in sand, fath., mc. with punctured sculpture. . p. pruinosa, _clark._--_bulla_ and _bullæa_.--devon, northumb., hebrides, etc. mud, to fath. n. eu. scaphander. . s. lignarius, _linn._ (_bulla._)--_b. oblonga_.--brit. co. generally. to fath. n. and s. eu., c. . s. zonatus, _turt._ (_bulla_)--young specimen taken at zetland by mr. jeffreys, resembling older norwegian specimens. more oval than _s. lignarius_. spire umbilicated. aplysia. . a. hybrida, _sowerby._--_laplysia depilans_, _a. depilans_ and _punctata_.--brit. co. generally. among seaweeds, to fath., c. pleurobranchus. . p. membranaceus, _mont._ (_lamellaria._)--devon, arran, cork, etc. low-water, mr. broad, flexible. . p. plumula, _mont._ (_bulla._)--guernsey, devon, skye, etc. littoral, r. narrow, less flexible. spirula. . s. peronii--once taken near swansea, imperfect. [illustration: british shells. plate xxi.] plate xxi. limnÆus. in and near fresh-water. fig. , . l. pereger, _müller_ (_buccinum._)--_helix_, _turbo_, _bulimus_, and _l. putris_, _inflata_, _teres_, _lutea_, _limosa_, _ovata_, _vulgaris_, _marginata_, _intermedia_, _lacustris_, etc.--springs and ponds, cc. . l. stagnalis, _linn._ (_helix._)--_buccinum_, _turbo_, etc., _stagnalis_, _fragilis_, and _major_, etc.--ponds, etc., not so generally as no. , , c. . l. palustris, _müller_, (_bucc._)--_helix_ and _l. fragilis_, _fontinalis_, _stagnalis_, etc.--ditches, ponds, etc., c. whorls more numerous and less rapidly enlarged than no. . . l. auricularius, _linn._ (_helix._)--_l._, _helix_, _bucc._, _turbo_, _bulimus a._, _patulus_, etc.--near london, swansea, etc., mc. aperture very wide, and outer lip partially reflected. . l. acutus, _jeffreys._--_l. auricularius_, var. b. m.--oban, clumber lake, bloomfield, kent, r. apex sharp and tapering; aperture smaller than no. . . l. truncatulus, _müller_, (_bucc._)--_h._, _b._, and _l. truncatus_, _fossarius_, _minutus_, _limosus_, etc.--partly amphibious, generally diffused, c. small, spire equal to body. . l. glaber, _müller_, (_buccinum._)--_h._, _b._, and _l. octanfracta_, _peregrina_, _elongata_, _octona_, _leucostoma_, etc.--fresh and brackish marshes, stafford, somerset, york, etc., r. spire longer than aperture. . l. involutus, _harvey._--_amphipeplea i._--lake near killarney, belfast, rr. spire almost covered. . l. glutinosus, _müller_, (_buccinum._)--_helix_, _amphipeplea_, and _l._--windermere, etc., mr. oval. . l. burnetti, _alder._--lakes in dumfries and breconshire. inflated; spire flat; colour opaque-amber. physa. in and near fresh-water. . p. hypnorum, _linn._ (_bulla._)--_helix_, _physa_, _limnæa_, and _aplexa turrita_ and _marmorata_. pools and lakes, brit. generally, c. . p. fontinalis, _linn._ (_bulla._)--_turbo_, _planorbis_, _bulimus_, and _ph. adversus_, _bulla_, _bulloides_, and _fluviatilis_.--brit. pools, lakes, and ditches, c. ancylus. in fresh-water. , . a. fluviatilis, _müller._--_patella lacustris._--running streams, on stones and plants generally, c. oval, apex turned to left. , . a. oblongus, _lightfoot_, (_patella._)--_a._ and _p. lacustris_. more lacustrine than no. , mc. oblong, apex turned to right. planorbis. in fresh-water. . p. corneus, _linn._ (_helix._)--_p._ and _h. cornu-arietis_, _purpureus_, and _similis_, _p. nana_ (young).--ponds and ditches generally, c. . p. albus, _müller._--_helix_ and _p. hispidus_, _hirsutus_.--distribution general, c. finely ciliated in lines. . p. glaber, _jeffreys._--_p. lævis_, alder.--penzance, falmouth, swansea, belfast, etc., mr. . p. nautileus, _linn._ (_helix._)--_p. imbricatus_, müller; _p. cristatus_, _turbo nautileus_, etc., mc. with horny ridges. . p. contortus, _linn._ (_helix._)--_p._and _h. crassa_, _umbilicata_.--distribution general, c. numerous close whorls; aperture semi-lunar. . p. carinatus, _müller._--_helix planorbis_, linn.; _p. planata_ and _lutescens_.--generally distr., c. whorls more rapidly increased than no. ; keel more distinct. . p. marginatus, _drap._--_h. planorbis_, _h._, _p. limbata_, _complanata_, _draparnaldi turgidus_, _rhombeus_, etc.--distr. gen., c. whorls more rhomboidal than . . p. vortex, _linn._ (_helix._)--_pl. compressa_.--distr. gen., c. many whorls, very compressed. . p. spirorbis, _linn._ (_helix._)--_p. vortex_, var.--distr. general, c. fewer whorls than no. ; mouth not angular. . p. nitidus, _müller._--_helix_ and _p. fontanus_, _complanatus_, and _lenticularis_.--most parts of brit., mc. very compressed. . p. lacustris, _lightfoot._--_p. nitidus_, var., _segmentina lineata_, _p. nautileus_ and _clausulatus_.--ponds and ditches near london, etc., mc. with internal divisions; lower disc flat. [illustration: british shells. plate xxii.] plate xxii. succinea. amphibious. fig. . s. putris, _linn._ (_helix._)--_h._, _s._, and _limnæa succinea_ and _amphibia_.--on plants by the side of rivers, ditches, etc., c. rather oval in form. . s. gracilis, _alder._--_s. putris_, var. _gracilis_, _s. amphibia_, var. _pfeifferi_.--by sides of streams and in damp meadows, c. elongated, with spire produced. . s. oblonga, _drap._--_helix elongata_, _amphibulina o._ and _e._--swansea, glasgow, etc. sometimes at a distance from water, r. spire with more distinct whorls. conovulus. partly marine, amphibious. . c. bidentatus, _mont._ (_voluta._)--_c._, _n._, _actæon_, and _auricula alba_ (var.) and _erosa_.--salt-water marshes, and on rocks near high-water mark all round our coasts, c. no tooth on outer lip. . c. mysotis, _drap._--_c. denticulatus_, var., etc.--brackish marshes, thames, etc., c. outer lip with one tooth. . c. denticulatus, _mont._ (_voluta._)--_c._, _v._, _auricula_, and _actæon ringens_, _reflexa_ (var. f. ), _mysotis_, and _personata_.--numerous places, near the sea, c. outer lip with many teeth. . c. reflexus.--_auricula reflexa_, _c. denticulatus_, var. _jeffreys_. carychium. . c. minimum, _müller._--_turbo carychium_, _auricula minima_.--moist places, wet mosses, etc. generally distr., c. limax. land slug, with shell under shield. . l. cinereus _müller._--_l. maximus_, _maculatus_, _limacella parma_. brit. gen., c.; eu. shell oval, large, thin. . l. agrestis, _müller._--_l. concava_ and _obliquus_.--brit, gen., c. _foss cr._ shell small, oblique. . l. brunneus, _drap._--_l. concava._--under stones, etc. shell minute, square. . l. flavus, _linn._--_limacella unguiculata_ and _variegata_.--the large cellar slug. shell thick, rather square. testacella. slug with shell on tail. . t. maugei, _férussac._--clifton, taunton, plymouth, swansea, etc., mr. large, and more square than . . t. haliotoidea, _drap._--_t. europæa_, _t. scutulum_.--near london. channel isls., etc., mc. vitrina. shell not including the whole slug. . v. pellucida, _müller_, (_helix._)--_h. diaphana_, _helicolimax_, _limacina major_, etc.--various parts of the country, under stones, etc., mc. eu. very transparent. . v. draparnaldi, _jeffreys._--_v. oblonga_, _h. brevipes_?--less globular than , r. zonites. transparent, thin-edged snails. , . z. cellarius, _müller_, (_helix._)--_h._ and _z. lucida_ and _nitens_.--brit. gen., c. , . z. nitidus, _müller_, (_helix._)--_h._ and _z. nitens_, _lucida_, _tennis_, _succinea_, etc.--less depressed than , , with larger umbilicus. . z. crystallinus, _müller_, (_helix._)--_h._, _z._, _discus_, and _"polita" c._, _eburnea_, _vitrea_.--in damp spots, among stones and moss. minute, white, transparent. . z. nitidulus, _drap._--generally distributed, mc. mouth oblique. umbilicus small. , . z. allarius, _miller_, (_helix._)--_h._ and _z. glabra_, _alliacea_, _nitens_, _tenera_, _lurida_, etc.--distr. gen., c. smaller and more convex than , . . z. excavatus, _bean_, (_helix_)--_h._ and _g. nitida_, _lucida_, etc.--durham, northumberland, galway, etc., mc. umbilicus very large. , . z. radiatulus, _alder_, (_helix._)--distr. gen., c. striated, minute. , . z. purus, _alder_, (_helix._)--_h._ and _z. polita_, and _helicella nitidosa_, _electrina_, etc.--most common north engl. whorls less close and more oblique than . [illustration: british shells. plate xxiii.] plate xxiii. helix. snails with thickened lips. fig. . h. pisana, _müller._--_h. zonaria_, _cingenda_, _rhodostoma_, _strigata_, _albella_.--cornwall, s. wales, dublin, c. s. and n. eu. . h. aspersa, _müller._--_h. grisea_, _hortensis_, _variegata_, _vulgaris_, etc.--common in all our gardens and hedges. . h. virgata, _costa._--_h. variabilis_, _ericetorum_, _zonaria_, etc.--in sandy and chalky places, c. more compressed than no. . . h. cantiana, _mont._--_h. pallida_, etc.--south and west engl., c. . h. ericetorum, _müller._--_h. itala_, _striata_, _albella_, _erica_, _nivea_, _cæspita_, etc.--chalky and sandy places, c. depressed, delicately banded; large umbilicus. . h. rufescens, _pennant._--_h. rufina_, _montana_, _cælata_, _clandestina_, etc.--most common in southern, chalky and limestone districts. depressed, striated; whorls slightly angular. generally lighter than our figure, sometimes nearly white. . h. lapicida, _linn._--_h. acuta_, _affinis_, _carocolla l._--chalk and limestone districts, c. s. and n. eu. sharply angular. , . h. hispida, _linn._--_h. rufescens_, _sericea_, _concinna_ (var. without hairs), etc., _plebeia_.--all parts of brit., c. more depressed than _h. sericea_, with larger umbilicus. . h. fusca, _mont._--_h. subrufescens._--brit. gen., mc. . h. sericea, _drap._--_h. hispida_, _globularis_, _granulata_, etc.--granulated, hairy. mouth wider than . small umbilicus. . h. obvoluta, _müller._--_h. trigonophora_, etc.--ditcham wood, hampshire. in moss at roots of trees, rr. . h. fulva, _müller._--_h. terrestris_, _trochiformis_, _nitidula_, etc.--pretty general and common. conical, minute, transparent. . h. pomatia, _linn._--southern chalky districts, s. eu., c. . h. caperata, _mont._--_h. striata_, _h. crenulala_, etc.--chalk-pits, etc., c. . h. carthusiana, _müller._--_h. nitida_, _carthusianella_, _rufilabris_, etc.--chalk-districts of surrey and kent, c. , . h. nemoralis, _linn._--_h. hortensis_, _fasciata_, _hybrida_, etc.--cc. a peculiar flattening near the base of aperture. . h. arbustorum, _linn._--common and general. brown-marbled. edge of aperture different from , . , . h. rotundata.--_h. radiata_, _turtoni_, etc.--common and general. , . h. pulchella, _müller._--_h. costata_, _paludosa_, _crenella_, _minuta_, etc.--common and general under stones, etc. . h. revelata, _férussac._--cornwall, devon, torquay, guernsey. rare. a transparent, greenish, hairy shell. . h. aperta.--_h. neritoides_, _naticoides_, etc.--a single specimen found in guernsey. not uncommon in s. eu. our specimen is foreign. . h. umbilicata, _mont._--_h. rupestris_, etc.--on perpendicular heights and under stones, c. . h. pygmÆa, _drap._--_h. minuta_, etc.--common in damp places. . h. lamellata, _jeffreys._--_h. scarburgensis_, _seminulum_.--brit. and germany, c. . h. aculeata, _müller._--_h. spinulosa_, etc.--among moss and stones, etc., c. general. [illustration: british shells. plate xxiv.] plate xxiv. bulimus. long snail. fig. . b. lackhamensis, _mont._--_b. montanus_, _montacuti_, _eua montana_.--kent, surrey, gloucester, selborne, n. and s. eu., r. as brit. shagreened. . b. obscurus, _müller._--_turbo rupium_, _b. hordaceus_, etc.--c. and general. surface smooth. , . b. acutus, _müller._--_helix barbara_, _b. cretacea_, _articulatus_, _turbo fasciatus_, etc.--on sand and limestone in marine neighbourhoods, c. pupa. small snails, among moss, stones, etc. . p. secale, _drap._--_turbo_, _helix_, _chondrus_, and _vertigo juniperi_ and _cylindricus_.--s. engl., channel isls., c. s. eu. larger and more tapering than the other sp. . p. umbilicata, _drap._--_turbo_, _bulimus_, _helix_, and _p. muscorum_, _cylindraceus_, _bidentata_, etc.--c. and general, eu. mouth oblique, long, one tooth. . p. muscorum, _linn._--_t._, _p._, _h._, _b. marginata_, _chrysalis_, _unidentatus_, etc.--c. and gen. a rib behind the outer lip. . p. anglica, _férussac._--_vertigo_, _turbo_, and _p. a._ and _ringens_.--scarborough, newcastle, guernsey, etc., mr. more cylindrical than . . p. edentula, _drap._--_h. exigua_, _vertigo_, _helix_, and _jamimia e._, _nitida_, etc.--c. and gen. no teeth in aperture; smooth. . p. minutissima, _hartmann._--_p._, _vertigo_, _alæa cylindrica_, _obtusa_, _muscorum_, etc.--bristol, salisbury, skye, etc., r. as brit.; c. in s. eu. no teeth in aperture; striated. , . p. pygmÆa, _drap._--_p._, _t._, _v._, _h._, _alæa_, etc., _sexdentatus_, _quinquedentatus_, _vulgaris_, etc.--the lighter variety, _p. alpestris_, c. and general. four or five teeth. . p. substriata, _jeffreys._--_vertigo_, _turbo_, _alæa sexdentata_, _curta_, etc.--c. and gen. very cylindrical; six teeth; striated. . p. antivertigo, _drap._--_p._, _v._, _alæa octodentata_, _septemdentata_, _palustris_, etc.--near swansea and london; bristol, devon, northumberland, ayr, mr. ireland. aperture subtrigonal, eight or nine teeth. . p. pusilla, _müller._--_helix vertigo_, and _v. heterostropha_.--s. wales, northumberland, belfast, etc., mc. sinistral, with seven teeth. . p. venetzii, _charpentier._--_turbo_, _vertigo_, and _p. vertigo_ and _angustior_.--swansea, cork, clare, r. sinistral; four teeth and a flat fold on columella. balea. . b. fragilis, _drap._ (_pupa._)--_bulimus_, _pupa_, _clausilia f._, _perversus_.--c. and gen. under bark on trees, and under stones. clausilia. with a twisted _clausium_ on columella. . c. laminata, _mont._--_helix_, _turbo_, _bulimus_, and _pupa bidens_ and _perversus_ and _derugata_.--s. brit. principally. among dead leaves, and on beech-trunks, mc. smooth, broad. . c. nigricans, _maton and rackett._--_strombiformis_, _turbo_, and _odostomia perversus_, _bidens_, _parvula_, etc.--c. and gen.; under stones, on walls and trees, etc. narrow, striated. . c. biplicata, _mont._--_helix_, _turbo_, _odost._, _c. perversa_, _plicata_, _ventricosa_, etc.--near london, etc., mc. two folds on columella. . c. plicatula, _drap._--_turbo_ and _c. conversus_.--charlton wood, kent, hastings, gloucestershire, etc., r. numerous plaits on columella above fold. zua. . z. lubrica, _müller_, (_helix._)--_turbo_, _bulimus l._, _subcylindrica_, _muscorum_, etc.--c. and gen. among leaves and under stones. azeca. . a. tridens, _pulteney_, (_turbo._)--_helix_, _pupa_ and _cionella goodallii_, _britannica_, etc.--c. and general. habits as _zua_ and _pupa_. achatina. . a. acicula, _müller._--_buccinum_, _bulimus_, _helix octona_, _terrestre_, etc.--in marshy places, among grass, etc., c. s. eu. cyclostoma. snail with operculum. . c. elegans, _müller_, (_nerita._)--_turbo reflexus_, _t. tumidus_, _striatus_, _elegans_.--chalky districts of s. engl., c. acme. cylindrical snail with operculum. . a. lineata, _drap._ (_auricula._)--_turbo_, _carychium_, _cyclostoma_, _bulimus fuscus_, _cochlea minuta_.--bristol, pembroke, clare, dublin, etc., r. * * * * * g. b. sowerby, junr., _supplies single specimens or large parcels of_ recent shells and fossils parcels will be sent for selection, to those who forward suitable credentials, in any part of the world, so that those collectors whose supplies have been interrupted by a recent lamented death can now have them renewed. g. b. s., junr., has a very large stock of shells, purchased from the vauterian and dennissonian collections, and from the stores of the late m. cuming, as well as from the sale of mr. reeve's stock, and other sources. collections of british shells. seventy-five named species, arranged in a box, having the appearance of a book in two volumes, one guinea. or a more extensive series prepared in the same manner. the recently described fossils from the lingula flags, south wales, supplied singly or in sets. books by g. b. sowerby, f.l.s. (_discount to direct purchasers._) thesaurus conchyliorum; or monographs of recent shells. parts and will be published before christmas, , containing additions to former monographs, and some new monographs; _completing vol iii. and the first series._ the new series, to be commenced early next year, will appear under improved conditions, and will be carried to a completion in as small a compass and as short a time as possible. illustrated index of british shells. _cloth gilt, imperial._ coloured figures of species, with names, localities, and other information. new proposed work, by g. b. sowerby, f.l.s. generic forms of shells illustrated. the author has long been engaged collecting materials for this work, which is to contain a harmonization of existing systems, in which a balance will be struck between a too negligent and too minute subdivision. comparative susceptibility of _definition_ will be the guiding principle in deciding the claims of certain groups to generic separation. the illustrations will be copious and of full size, embracing every marked form, whether recent or fossil, and whether adopted as a genus or not. the price is not yet fixed, but is expected to be about £ s. to appear between march and may, . g. b. s., jun., will be glad to receive the names and addresses of those who desire to see the work when published. , great russell street, bloomsbury. * * * * * natural history agency offices, conducted by g. b. sowerby, f.l.s., , great russell street, bloomsbury. _collections bought, sold on commission, or prepared for auction._ stock on hand. fossils. crag.--numerous fine teeth, bones, and shells. london clay.--fish-heads, teeth, fruits, teredinæ, etc. chalk and gault.--a magnificent series, including fine specimens of goniaster, cidaris, ventriculites, crustacea, shells, etc. greensand.--a comprehensive series from blackdown, cambridge, etc. oolites.--a fine specimen of the new cidaris (block with five individuals and many long spines), extensive minchinhampton series, etc. lias.--ichthyosaurus,--a fine museum specimen, mounted ft. in.,--plesiosaurus, teleosaurus, a most beautiful specimen of lepidotus, and numerous other fishes in fine condition. coal.--fine specimens of lepidodendron, sigillaria, ferns, etc. devonian fishes, plants, etc. recent shells. among a most extensive range of genera and species are included voluta rossiana, v. fulgetrum, conus aurisiacus, c. princeps, c. marchionatus, a fine series of c. venulatus, etc., halia priamus, cypræa picta, cardium hians, c. Æolicum (true), galathæa concamerata, velorita, anastoma, beautiful spondyli, etc. series of british shells made up. minerals. a very extensive series of specimens; also illustrative collections. birds and insects. a fine collection of british and other birds in cases. beautiful rosewood cabinet ( drawers), with fine butterflies, etc. beautiful mahogany cabinet ( drawers), with fine butterflies, etc. books, new and second-hand. works on crustacea, including milne-edwards' 'histoire;' desmarets' 'considérations;' roux, 'crust. de la méditerranée;' 'crustacea of the fauna japonica,' etc.; on zoology, the 'historia de chili;' 'journal de conchyliologie,' by crosse; bernardi's 'monog. des galathées,' etc.; supplement to sowerby's 'cones;' deshayes' 'coquilles fossiles de paris;' sowerby's thesaurus conchyliorum, pt. to ; sowerby's 'wild flowers;' and new edition of sowerby's 'english botany.' thesaurus conchyliorum, parts at _s._ each. illustrated index of british shells, coloured figures, with names, localities, and other information; by g. b. sowerby, f.l.s., etc. impl. cloth gilt, _s._ labels, _d._ *** _further particulars will be furnished. sets made up to illustrate formations, classes, or genera, and specimens forwarded on approval._ transcriber notes text emphasis is displayed as _italics_. rudiments of conchology; with explanatory plates. [illustration: rudiments of conchology.] rudiments of conchology: intended as a familiar introduction to the science. with explanatory plates, and references to the collection of shells in the british museum. by the author of "the geographical present," &c. [illustration: a new and improved edition.] london: darton and harvey, gracechurch street. . london: printed by joseph rickerby, sherbourn lane. advertisement. the compiler of the following pages has derived the greater part of the information contained in them from "the conchology of lamarck," from "burrows's elements of conchology," and other introductory treatises. in the present edition of this little work many alterations and additions have been made, with the hope of rendering it more useful to the young student. errata. [note: corrections were applied.] page , _for_ plate , _read_ plate . page , line , _for_ squamosa, _read_, squamosus. page , _for_ candidas, _read_ candida; and _for_ plate , _read_ plate . page , _for_ plates and , _read_ plates and ; and _for_ gædaropus, _read_ gæderopus. page , _for_ epiphippium _read_ ephippium. page , line , _delete_ not. page , line , _read_ plate . page , _read_ bruguieres; and _for_ pollicepes, _read_ pollicipes. page , line , _read_ parmophorus--line , _read_ plate . page , line from bottom, _read_ carocolla. page , line , _for_ valvata _read_ voluta. page , line , _read_ anglicanum. rudiments of conchology. chapter i. introductory. "a box full of shells!" said charles to his sister lucy, who was looking over her treasures with great attention. "what can you want so many little shells for?" "this box and its contents are the gifts of my cousin jane," replied lucy: "she said that i might have her whole collection, if i could find any pleasure in looking at shells without knowing anything about them. but i am not _quite_ ignorant of the subject." "shells are pretty enough," said charles; "but how troublesome to distinguish the differences between each kind! i like plants better than shells." [sidenote: multivalves, bivalves, univalves.] "probably because you are better acquainted with plants," observed his father, mr. elliot, who had just entered the room: "however, the great naturalist, to whom you are indebted for your knowledge of plants, did not consider shells as objects beneath his attention." "you mean linnæus," said lucy; "then he, i suppose, separated shells into the three different divisions--_multivalves_, _bivalves_, and _univalves_." "you are right, lucy," replied her father. "pray show me some bivalve shells," said charles; "i want to know their forms. a _bivalve_ is a shell with two openings, as i should imagine: yes, i see that i am right, for you have given me an oyster and a cockle." "here are also _venus_, _tellìna_, _donax_, _arca_, and _pinna_," observed mr. elliot, "all very easy to distinguish." "'the anchor'd pinna and his cancer friend,'" repeated charles. "so the _pinna_ is a bivalve; but what has _venus_ to do with the matter?" "that is very easy to understand," said lucy: "the genus called by her name is remarkable for beauty." "now, charles," said mr. elliot, "do you clearly comprehend the verse that you have just repeated?" [sidenote: the pinna and the cancer.] "i have heard that the _pinna_ is a shell-fish, attended by a _crab_, 'his cancer friend;' but why it is called _anchor'd_ i do not know, but _cancer_ is latin for crab." "here is a species of _pinna_," said his father, opening a cabinet; "and these silken threads are the means by which it fastens itself to the rocks. the animal is provided with a long foot, with which it draws out the threads, or _byssus_. the _pinna_ is sometimes called the silk-worm of the sea. lucy, do you know a univalve shell?" "oh yes, many!" replied lucy, "here are rock-shells, cowries, limpets, and cones. i know the difference between a cowry and a cone; but i am not yet acquainted with a multivalve shell--will you show me one?" "_chiton_, or coat of mail, is a good example," said mr. elliot; "_pholas_ is another genus of the same division; it has the appearance of a bivalve. in the _chiton_ are several _lamina_, or plates, which are connected by a membrane while the living animal is in the shell; the membrane is pliant, and the inhabitant has the power of contracting itself into a ball, when it would avoid injury, like the insect millepes, that we find under stones in damp places. (plate .) the curious barnacle-shell, _lepas_, is another multivalve." (plate .) "i think we cannot have a more agreeable pursuit for our leisure hours," said lucy, "than the study of shells. one can bring them out or remove them so easily, that they can cause little inconvenience, which garden-pots often do in town; and then the plants are almost sure to die, whatever care i take of them." [sidenote: lamarck's system.] "collections of shells are frequently to be seen in london," said mr. elliot, "which are intended for sale. there are now many places where shells are sold at moderate prices, and young collectors like yourselves can easily avail themselves of the means thus afforded, to obtain even a single specimen. while we remain in town you may visit the british museum, and become familiar with the rare species of each genus, of which there are many costly specimens. the arrangement adopted for that collection is lamarck's. you will find the work of this celebrated naturalist on my shelves; it is entitled, '_histoire naturelle des animaux sans vertèbres_.' the three last volumes contain the conchology." "it is in french and latin!" exclaimed lucy, as she opened a volume. "why do you both look so serious?" asked their father. "are you not students in those useful languages? to what purpose do you learn a language if it be not with a view to reading the works of learned men, whose labours have opened a wide field of knowledge?" [illustration: plate .] [sidenote: use of the latin language.] "but so many works on science are written in latin," said lucy. "linnæus, however, has been translated, i know; and as for _british_ botany, we have our own authors in my own dear language." "the latin language being universally studied by men of science, it has become the medium of communication between the learned of most countries," observed mr. elliot. "i should consider a young person of your age, lucy, very ignorant who could not read and understand the general style of lamarck with the occasional aid of the dictionary." "do not be discouraged, brother," said lucy, "my father will assist us: remember how frequently he helps us with our lessons now, provided we do our best. i am resolved to obtain some knowledge of shells this winter." "a very good resolution," said mr. elliot; "and i predict that your usual delight on revisiting our favourite country dwelling will be somewhat increased next spring." "because i shall carry down my little collection with the pleasure of knowing more than i did last year." "our own coasts, rivers, and ponds afford a variety of shells. the hedge-banks, heaths, and other places, possess their inhabitants." [sidenote: pleasure of searching for shells.] "oh," exclaimed lucy, "i quite forgot the very pretty snails i have so often admired on the heath on a dewy morning: why, we may learn conchology in the open fields as well as botany!" "well, then," replied mr. elliot, "to-morrow we will apply ourselves to the needful instruction. i must, however, remind you that i do not approve of any animal's life being taken away in order to obtain its habitation. empty shells are to be found, which will serve perfectly well for specimens; and should the colour not be so bright as you could wish, you will have the delightful consciousness that your amusements have been free from cruelty, and that you have not destroyed the life of any living, harmless creature, in the pursuit of pleasure. indeed there is as much or more gratification in searching among the rocks, or digging into the sea-sand, with a view to watch the animal in its natural place, as in possessing its empty shell: and who knows what grand discoveries you may both make! "but i must leave you now--be ready for me after our usual dinner-hour." chapter ii. [sidenote: inhabitants of shells.] "conchology," said mr. elliot, on resuming the conversation with his children, "is that branch of natural history which comprehends the study of testaceous animals, or animals with _shell-coverings_, and includes those of the seas, the rivers, and the land. "all shells are formed of carbonate of lime. this you may easily prove by applying a little acid to a shell, and you will find that an effervescence takes place. "the animals that inhabit shells are bloodless, without bones, but provided with a heart, lungs, and mouth, together with other organs needful to their conformation. "testaceous animals have the power of enlarging their habitations; they can also repair any injury that may occur to them. "many kinds of shell-fish are made use of by man, and form a valuable article of food, such as oysters, cockles, muscles, scallops. the whelk is also used, and a species of murex. [sidenote: fossil shells.] "a species of cowry is in use for money among some people of africa; and pearls, so much valued as articles of ornament, are obtained from the oyster and mussel genera. "within a few years, conchology has become a study of considerable importance, from its close connexion with geology. students in the latter science must be well acquainted with fossil-shells, because they form so large a portion of organic remains. species of recent shells, or those still existing, are also often found in a fossil state, while many fossil genera are now totally unknown in our earth and waters. "thus you perceive that while you are obtaining knowledge in one science, you are preparing yourselves for making advances in another, most interesting and wonderful. you, charles, who are likely to become a traveller, will perhaps in future years find the advantage of my present brief lessons. "i shall first endeavour to make you acquainted with the system of linnæus; it is easily learned, and you should be familiar with it, as it is still adopted by some writers on conchology. "but in order to understand my instructions, you must have a clear idea of the terms that i use in describing a shell; now, therefore, give me your attention while i explain some of those terms to you. [illustration: plate .] [sidenote: terms for parts of multivalves.] "to begin with the first division, _multivalves_. there is a group of _lepades_, it is the species called goose-barnacle, of which so many strange and silly tales have been told in former times. (plate , _lepas anatifera_.) this species is furnished with a kind of stem, like a bladder, and is called the _peduncle_, (_c_) and is fastened to other bodies. the _feelers_ (_d_) are feathery projections, which the animal keeps in continual motion, for the purpose of catching its food. here is a group of another kind; (plate , _lepas tintinnabulum_;) these are without a peduncle, and are called _sessile_. the _base_ (_a_) is that part of the shell by which it is fixed to other bodies: (_a_) the _operculum_ is formed of four small valves on the summit. (_b_). * * * * * "in the shells of the second division, _bivalves_, we shall find a greater number of parts. _valves_ are the different pieces that compose a shell. when both the valves are alike in form, the shell is called _equivalve_: when the valves are different in the same shell, it is called _inequivalve_. _mya_, _solen_, _tellina_, are equivalves: _ostrea_, _anomia_, _pinna_, &c. are inequivalves. [sidenote: terms--bivalves.] "the _hinge_ is formed by the teeth of one valve inserting themselves between those of the other valve, in some genera; in others, by the teeth fitting into the _cavities_ of the other valve (plate ., _a_.) when the teeth are placed in the centre of the hinge they are called _cardinal teeth_. _lateral teeth_ are situated on the sides of the valves, and are generally long and flat, sometimes hollow. some hinges are straight, others curved. here is the hinge of _arca_, furnished with many small teeth. (plate , _b_.) "the _ligament_ is a membrane that connects the valves, and keeps the hinge in its proper place: it is always situated near the beaks. the ligament is very perceptible in the cockle, in _pecten_, or scallop, in _tellina_, &c. "the _beaks_ are the most pointed parts of the bivalve shell (plate , _c_.); when the valves are closed, the line where they meet is called the _seam_. (plate , _d_.) "the _anterior slope_ is that part of the shell where the ligament is placed, and is also called the _area_. (plate , _e_.) the _posterior slope_, or _areola_, is the other side of the beaks. (_f._) "the _lunula_ is a crescent-like depression on either the area or areola. the edge of the valve is called the _margin_; it is often finely _crenulated_, or toothed. the interior of the valve is called the _cavity_. (_g._) in the valves of this ark-shell here are two broad marks, shining and glossy. (_g._) in those of the oyster and muscle that i now show you, there is but one. these marks are _muscular_ impressions; they are the parts where the muscles of the animal have been affixed, and are termed _cicatrix_. [illustration: plate .] [sidenote: terms--univalves.] "_ears_ are two processes on each side of the beak; the _pecten_, or scallop, is an example. (plate , _i_.) "_sinus_, in _bivalve_ shells, is a small hollow in the hinge. "_byssus_, or beard, is an appendage composed of silky threads, by which the muscle and _pinna_ fasten themselves to the rocks. (plate , _f_.) "_cordiform_ is a term applied to heart-shaped shells. "a _cartilage_ is the same as a ligament. when the valves of a shell are very nearly flat, they are said to be _compressed_: when a valve has teeth, it is said to be _dentated_. "when the valves of a shell do not shut close, they are said to be _gaping_. (plate , _mya_.) "a _muscle_ is a fleshy, pliant organ, by which the animal is attached to its shell. i have already pointed out to you the impressions of those muscles within bivalve shells. "a _suture_ is a toothed joint, in bivalves. "a shell with ears is said to be _auricled_. * * * * * "the third division, _univalve_ shells, have also their several parts. the first section has a regular spire. here are two shells of this section, _voluta_ and _buccinum_, both sawed asunder, in order to show the interior structure of the shell. (plate .) the aperture, or opening, being turned _towards you_, the front of a univalve is seen; reverse it, and you see the back. [sidenote: terms--univalves.] "the top, or highest part, is the _apex_; (_a_) the lowest part is the _base_ of the shell. (_b._) "the _spire_ (_c_) is formed of wreaths, or whorls, (_ddd_) which terminate in the apex: the lowest whorl is the body of the shell. (_e._) "the _aperture_, opening or _mouth_, (_f_) as it is sometimes called, is on the right-hand when the front of the shell is turned towards you. the aperture is an important distinction in univalves: some genera have a circular opening, as the _turbo_, or periwincle; some longitudinal, as the cowry; others semi-lunar, as the _helix_, or snail genus. (for examples of these apertures see plates and .) "the _beak_ is the lengthened process (_g_) at the lower part of the shell. "the _canal_, or _gutter_, runs through the beak. (both these parts are perceptible in _murex_ and _strombus_, plate .) "_sutures_ are spiral lines which separate the whorls; they are sometimes crenated, or notched, sometimes sulcated, or furrowed. "the _columella_, or _pillar_, extends through the centre of the shell withinside. the _buccinum_ and _voluta_ both show the columella. (plate .) [sidenote: terms--univalves.] "the _pillar-lip_ of the aperture, or columella margin, is on the left-hand side of the shell; the _outer_ lip on the right-hand. occasionally this order is reversed, but not commonly. "the _operculum_, or lid, in univalves is that part which fits exactly into the aperture, and incloses the animal; it serves as a door to the shell. (plate .) the operculum is either horny, like that of the periwincle, or of a harder substance, like the shell itself. "the _umbilicus_ is a circular hole in the body of the shell. this perforation produces a very curious effect when it is very large. when the umbilicus is wanting, the shell is called _imperforate_. "if the spire is truncated, it is _decollated_; if it is surrounded with spires, it is _coronated_, or crowned. * * * * * "second section, without a regular spire. the _teeth_ in univalve shells, as the cowry, are ridges upon the aperture. (plate .) in _voluta_ they are regular folds or plaits upon the columella. "a _fissure_ is a notch or slit, as in _patella fissura_. (plate .) "some shells of this section are internally lipped, as _patella equestris_; (_calyptræa_ of other authors, plate ;) some are chambered, as the slipper-limpet; some are cap-shaped, having the apex much curved--these are the cap-limpets. [sidenote: terms--univalves.] "the _vertex_ in _patella_ is as the superincumbent part of the shell. "the _epidermis_ is the outward skin that covers the surface of some shells. "_fauces_ are narrow entrances, as at each end of the cowry. "_tubercles_ are protuberances, or knobs, on the surfaces of shells. "_striæ_ are raised or flat lines upon the surfaces of shells. when the surface is marked with lines longitudinally and transversely, it is _decussated_. "_sulci_ are furrows. "_fornicated_ signifies arched, greatly excavated. "_umbo_ is the swelling part near the beak of bivalve shells; the same as _boss_. "_longitudinal_, running nearly the whole length of the shell in univalves. "_concentric_, having the same centre. "_convolute_, when the exterior whorls spirally involve the interior. "_varices_, longitudinal, gibbous sutures formed in the shell, at certain distances on the whorls. "_carinated_, having the form of the keel of a boat." chapter iii. [sidenote: system of linnÆus.] "as you both assure me," said mr. elliot, "that you do not fail to make yourselves familiar with the _nomenclature_, or terms, used in conchology, i shall proceed this morning to the arrangement of linnæus. "this system is established upon the _outward_ appearances, or external characters, of the covering bestowed by nature upon the animal, not upon the form of the animal itself. "the three principal divisions you are already acquainted with, namely, _multivalves_, shells composed of several parts called valves; _bivalves_, formed of two parts; and _univalves_, composed of one part or piece only. "these divisions contain several _genera_, and the genera usually include many individual shells, but occasionally only one. "the characters of every genus are permanent, and are therefore to be observed in every one of the species contained in the genus. "species are determined by shape, colours, or appearances on the surface of the shell: there are sometimes many varieties of the same species. [sidenote: linnÆan genera.] "the linnæan genera are thirty-six. i have copied a list of them for you. in that tray are the specimens mentioned in your list: arrangement of linnÆus. first division--_multivalves_: genera. * _chiton_, coat of mail, example, _c. squamosus_. * _lepas_, acorn-shell or barnacle, ex. _l. anatifera_ and _tintinnabulum_. * _pholas_, stone-piercer, ex. _p. candida_. second division.--_bivalves_: genera. * _mya_, trough-shell, ex. _m. truncàta_. * _solen_, razor-sheath, ex. _s. siliqua_. * _tellìna_, wedge-shell, ex. _t. feroensis_. * _cardium_, cockle, ex. _c. cardissa_. * _mactra_, kneading-trough, ex. _m. stultòrum_. * _donax_, wedge-shell, ex. _d. trunculus_. * _venus_, venus, ex. _v. paphia_. _spondylus_, thorny-oyster, ex. _s. gæderopus_. _chama_, clamp-shell, ex. _c. gigas_. * _arca_, ark-shell, ex. _a. noæ_. * _ostræa_, oyster, ex. _o. isognomon_. * _anomia_. antique lamp, ex. _a. ephippium_. * _mytilus_, muscle, ex. _m. edulis_. * _pinna_, wing-shell, ex. _p. pectinàta_. [sidenote: linnÆan genera.] third division: sections.-- st. _univalves_ with a regular spire: genera. _argonauta_, paper-sailor, ex. _a. argo_. _nautilus_, sailor, ex. _n. pompilius_. conus, cone, ex. _c. hebræus_. * _cypræa_, cowry, ex. _c. monèta_. * _bulla_, dipper, ex. _b. naucum_. * _voluta_, wreath, ex. _v. utriculus_. * _buccinum_, whelk, ex. _b. reticulatum_. * _strombus_, screw, ex. _s. pes-pelicàni_. * _murex_, rock-shell, ex. _m. ramòsus_. * _trochus_, top-shell, ex. _t. bifaciàtus_. * _turbo_, wreath, ex. _t. muricàtus_. * _helix_, snail, ex. _h. nemoràlis_. * _nerìta_, nerite, ex. _n. striàta_. * _haliòtis_, ear-shell, ex. _h. tuberculàta_. * * * * * nd section, without a regular spire: genera. * _patèlla_, limpet, ex. _p. vulgàta_. * _dentàlium_, tooth-shell, ex. _d. elephantìnum_. * _sérpula_, worm-shell, ex. _s. triquétra_. _terèdo_, ship-worm, ex. _t. navàlis_. * _sabella_, sabella, ex. _s. belgica_. total number of genera in the arrangement of linnæus, thirty-six. the genera marked with an asterisk, contain species found in britain. [sidenote: chiton. lepas.] "multivalves may be divided into two kinds, the _pedunculated_, or those fixed to other bodies, as rocks, stones, planks, &c.; or _free_, as the _chiton_ and _pholas_. "our first genus is _chiton_. the shell is easily known. the fixed character is, many valves placed over each other along the back. i have already noticed the membrane which connects the valves, which is also a permanent character. it is elastic: the sides are either scaly, as in _c. squamòsus_, (plate ,) and hairy, or spinous. the species are determined by the margins. some of the chiton genus are common upon our own coasts; they are frequently found among seaweed and stones, rolled up like a ball. _c. fasciculàris_ and _c. lævis_ are british; there are some other british species. the animal adheres to rocks, like the _patella_, or limpet. the number of species forty. "second genus, _lepas_. shell multivalve, fixed at the base; valves erect, or _upright_. "observe how much the situation of the valves differs in _chiton_ and _lepas_. it is scarcely possible to mistake the one for the other. the feathery tentacula, or feelers, of _lepas anatifera_ are worthy notice, and in a state of motion must be yet more beautiful. (plate .) the common acorn-shell, _l. balanus_, is to be seen very frequently upon the shells of muscles, oysters, periwincles, whelks, in large groups. i see that you are examining the different appearance of the pedunculated and the sessile _lepades_. linnæus made two divisions; later writers have separated them into several distinct genera, which will be noticed when we attend to lamarck's system. the species are forty-five, of which several are found on the british shores, as _l. tulipa_, _l. diadema_, _l. tintinnabulum_, _l. balanus_, _l. anatifera_, &c. the indian, american, and atlantic oceans afford numerous species. [sidenote: pholas.] "third genus, _pholas_. generic character: shell bivalve, gaping or divaricated, with several smaller hinges situated upon the hinge; hinge recurved, with an incurved tooth." "father," said charles, "i must say that the _pholas_ shell is very unlike those of the multivalve division: i think it should rank with bivalves." "so many conchologists have judged; nevertheless it possesses more than _two_ valves, and, according to the system, it must be forced into the division of multivalves. "the _pholades_ are found in company, but each individual occupies a distinct habitation, which the animal excavates for itself, either in rocks, in wood, coral, or sponge; but the finest specimens are usually to be seen in chalk. in proportion as the animal increases in size, it enlarges the cavity in which it is stationed. the animal is supposed to effect this operation by means of a corroding fluid that is secreted in the body, and which it has the power of ejecting upon the substance into which it has entered. [sidenote: pholas.] "the _pholas_ has the power of emitting a phosphoric liquor, which shines with brilliancy in the dark. "i must remind you that the accessory valves are fixed to the margin of the shell by a gelatinous substance; this decays after the death of the animal, and consequently the smaller valves are frequently wanting. "the number of species is twelve. several of them are found on our coasts. the _pholas_ genus is without colour, but the reticulations in some species are exceedingly delicate. _pholas candida_ (plate ) is found on the shores of kent; you will be pleased with the shells. _pholas dactylus_ is larger and coarser, and not at all uncommon. "we have now finished our first division, and must proceed to the bivalves." chapter iv. second division.--_bivalves_: genera. "i fear," said charles, "that this new division will be rather difficult, for my father tells me that we must pay particular attention to the _hinges_ of bivalve shells." "then _apply_ yourself to the study of hinges, charles, and your difficulties will chiefly disappear," answered mr. elliot. [sidenote: mya.] "the hinge of _mya_, the first on the list, is easily known. the generic characters are, shell gaping at one end, hinge mostly with one thick spreading tooth, not inserted into the opposite valve. the _mya_ race burrow in the sand. here is _mya arenaria_, a large thick shell, frequent on the shores of kent: the large tooth is sufficiently plain in _this_ species. _mya truncata_ (plate ) is as common, and the curious membranous case, which you will find attached to one end of the shell, is a guide to the species. both these species are without colour, and have little to attract in their outward appearance. the genus, however, according to linnæus, varies exceedingly, and contains forty-one species. [sidenote: solen. tellina.] "_solen._ shell bivalve, open at both ends, tooth of the hinge subulate, or awl-shaped, reflex, often double. "in this genus, the great length, in comparison with the breadth of the shells in many of the species, is remarkable: some are exceedingly brittle. our example, _solen siliqua_ (plate ) is a british species. the hinge is not in the centre of the shell, but nearer to one end of it. some are shaped like the handle of a knife or a razor, others are bent resembling the blade of a scimitar. the _solen_ lives in the sands of the sea-shore, often burying itself two feet deep, and retaining its shell in a vertical position: thirty-five species. "the genus _tellìna_ is remarkable for the beauty of the shells, and, according to the arrangement of linnæus, contains ninety-seven species. the exterior is sometimes marked with radiations: the surface of some shells is very finely polished, while in others it is covered with striæ and undulations. the species that you have placed before me, lucy, is _tellìna feroensis_; the shell is finely striated, and has also radiations. (plate .) "the generic characters are chiefly these: shell compressed towards the anterior slope, teeth of the hinge mostly three, the lateral ones smooth, in one valve. two or three small species are common on our coasts. i should also observe that there is a convex fold on one valve and a concave fold upon the other. many of the _tellìna_ genus are found buried in the sea-sands. [sidenote: cardium. mactra.] "_cardium._ generic character: shell equivalve, convex, ribbed, striated, or grooved, the margin toothed: hinge with two teeth near the beak, and a lateral one on each side: fifty-four species. "observe how the beaks of this common _cardium_, cockle, turn inwards, and the bosses project. another striking character is the ribs, that are generally longitudinal, and not concentric or transverse, as in _tellìna_, and, as you will see, in _venus_. _c. aculeatum_ has small spines on the valves; _c. costatum_, the ribbed cockle, is one of the finest species of this genus, and _c. cardissa_ is a beautiful shell. (plate .) the common cockle is _cardium edule_. _mactra._ generic character: shell bivalve, unequal sided, middle tooth of the hinge complicated, with a small hollow on each side, and lateral side-teeth: thirty-seven species. "the shells of this genus are usually thin, brittle, and remarkably light. _mactra stultorum_ is a common species. (plate .) [sidenote: donax. venus.] "_donax._ margin of the shell often crenulate, the anterior slope very obtuse; hinge with two cardinal teeth, and one lateral tooth. "the most striking characteristic of _donax_ is the broad, thick extremity of one end, gradually lessening towards the other. a rich purple tint is very frequent in these shells. _donax denticulatus_ and _trunculus_ are common british examples. (plate .) you must remark the ligament of _donax_, which is exterior. "our next genus ranks highest for beauty among the bivalves, and takes its name from the goddess _venus_. the species amount to one hundred and sixteen in the linnæan system, but other authors have formed several new genera. "shell bivalve, having the lips incumbent on the anterior margin; hinge with three teeth, all approximate, the lateral ones diverging at the lip. "i am afraid," said lucy, "that we shall find this genus very difficult: i wish you would tell us the new genera that have been formed out of it." "learn first to know the general appearance of _venus_, and remark especially the _teeth_. you may also bear in mind that the _beaks_ are almost always turned _to_ the posterior slope, and _from_ the ligament. the area and areola are also very conspicuous: the area is generally large, and differently coloured to the disk. _venus paphia_ is pretty. (plate .) the spinous species, _v. diòne_, is more beautiful, and is the only shell of the genus that has spines. the brown venus, _v. chionè_, is very smooth and polished; both species are frequent in collections. the british shells of this genus are neither numerous nor very beautiful. [illustration: plate .] [sidenote: spondylus.] "_spondylus._ valves unequal, rough; hinge with two recurved teeth, with a hollow between them; shell sometimes eared. (see plates and .) "i think," said lucy, "that the english name, _thorny-oyster_, is not very suitable: it is more like a scallop; but it differs from both in having two strong teeth in the hinge, and i observed this morning that neither the oyster nor the scallop have any hinge." "so that was the object you had in view," said charles, "when you were so quietly handling those shells in the kitchen: i confess i could hardly help laughing; and now my father will say that _you_ are '_eyes_,' and i the '_no eyes_,' of 'evenings at home.'" "perhaps i might have made the observation," replied mr. elliot; "but you have reproved yourself, which is far better. "_spondylus_ can scarcely be mistaken from any other bivalve shell. the species _gæderopus_ is remarkable for its projecting beak; the surface is rough, with either tubercles or spines. some authors reckon only four species, others thirteen. the _spondyli_ are frequently found attached to rocks at some depth in the ocean. the animal is eaten on the coasts of the mediterranean. we have no british _spondylus_. [sidenote: chama. arca. ostrea.] "_chama._ shell thick; hinge with a thick tooth, sometimes crenate, obliquely inserted into a corresponding channel. (plate .) the shells of this genus vary greatly, which you will perceive upon comparing _c. gigas_ and _c. cor_. (see plate , _isocardia cor_.) the _chama_ genus is usually ribbed, foliated, or scaly. _c. lazarus_ is a beautiful species: _c. cor_ is a british species, and the only one. the whole number is twenty-five. "here is _noah's-ark_, an example of the genus _arca_, and is found on our own coasts. the long hinge beset with sharp teeth, inserted into each other, renders the genus sufficiently marked; but in some species the hinge is curved. the form varies exceedingly. the number of species is forty-five. (plate .) "_ostrea._ in this well-known genus we lose sight of the _toothed_ hinge. take that _pecten_, or scallop, which belongs to one division of _ostrea_ in this system, and tell me what holds the valves together. charles is silent; what says lucy?" "here are the remains of the same kind of substance which we saw in _donax_ and in _venus_. i think it is called the _ligament_." [illustration: plate .] "very well remembered," continued her father. "the generic character of this very large portion of bivalves is, shell bivalve, usually with unequal valves: hinge without teeth, having a hollow cavity or sinus, and sometimes grooved. here is a young common oyster, and, according to the rule of our present system, this shell, _ostrea isognomon_, is of the same genus. (plate .) the number of species is eighty-four, of which thirteen are british. the old shells of common oysters are often covered with _serpula_, _lepas_, and _anomia_, and some kinds of corallines. [sidenote: anomia. mytilus.] "the next genus, _anomia_, is remarkable for the thin, delicate, and almost transparent appearance of the shells. the valves are unequal, and frequently perforated near the apex; hinge toothless; in the flat valve, two bony rays. "_anomia ephippium_ has a large perforation, through which the animal passes a ligament, and attaches itself to other substances. these shells are often to be found on oysters. (plate .) species thirty-two. "_mytilus._ the principal characters are, shell bivalve, rough, often affixed by a thick byssus, or beard; hinge without teeth, with a hollow line extending lengthways. (plate .) "the common muscle, _mytilus edulis_, must be well-known to you, and also the fine polish that the shells will take when cleared of the rough exterior by artificial means, _mytilus barbatus_ is not unfrequent on our shores; the colour is brown, and the shell is shaggy. number of species, forty-nine. [sidenote: pinna.] "our last bivalve genus is _pinna_. the generic characters--shell bivalve, brittle, erect, gaping at one end, throwing out a byssus; hinge without teeth. (plate .) "the _pinna_ race are found plentifully in the mediterranean, the indian, american, and atlantic oceans: the british seas afford three species. the genus is noted for producing a fine byssus, that is manufactured in italy into various articles, as gloves. the animal is sometimes used as an article of food. "an ancient writer asserts that the _pinna_ is attended by a crab, that finds a habitation in its shell, and repays the favour by giving notice, by a gentle nip, when a fish comes within reach; the _pinna_ opens the valves of the shell, and secures the prey, which serves for the food of both. now, charles, you know the whole sense of the quotation-- "'the anchor'd pinna and his cancer friend.'" chapter v. third division.--_univalves._ "father," said lucy, the next time they met to pursue their study, "i think we have made ourselves familiar with the various hinges of the bivalve shells, which are becoming favourites with us; but from the variety of fine specimens which you have on your table, i see that we shall be much gratified in examining the univalve division." [sidenote: argonauta.] "my first genus is very beautiful," replied mr. elliot; "it is _argonauta_, or paper-sailor. the shell is univalve, involute, unilocular, or without chambers: the aperture cordate. (plate .) these shells are spiral, and remarkably brittle. the argonauts are supposed to be the shells that taught mankind the use of sails in the earliest ages of society. in calm weather the animal rises with its shell to the surface of the water, and spreads its arms over the edge; these arms answer the purpose of oars. it then spreads a membrane for a sail, which can be turned in any direction, and is impelled forwards by the breeze: two other arms serve as rudders to direct the course. the animal first raises itself to the surface of the sea by ejecting a quantity of water; if danger occurs, it absorbs water, and thus, by making itself heavier, sinks to the bottom. the species are few in number. [sidenote: nautilus. conus.] "_nautilus_, pearly sailor, has several characteristics of _argonauta_; but the former is concamerate, the latter without chambers in the shell. the generic characters of _nautilus_ are, shell univalve, divided into several compartments, communicating with each other by an aperture. _nautilus pompilius_ is often cut through, or bisected, to display the chambers of the shell. in the east, the shells are formed into drinking-cups. sometimes the outer coat of the shell is removed, and the pearly surface finely carved. this genus, according to linnæus, consists of fifty-eight species, some of which are fossil. (plate .) "in the following genera we must pay particular attention to the _aperture_ of the shell, which is a generic distinction in most univalves. [illustration: plate .] "the first is _conus_, a large and beautiful genus, including many rare and valuable species. shell univalve, turbinate, aperture effuse, or having the lips separated by a sinus, linear, without teeth, pillar smooth. in their natural state the shells are usually covered with an epidermis; but will bear a brilliant polish. _c. textilis_, cloth of gold, is valuable. _c. generalis_ is sometimes sold for twenty guineas. the example on the table is _c. ebræus_, or hebrew cone. (plate .) species one hundred and fifty-five; not one british. the greater number are brought from the indian ocean; some from the seas of africa and from the south sea. [sidenote: cyprÆa. bulla.] "the shells of the genus _cypræa_, cowry, are general favourites: the species are fifty-eight; one british, _c. pediculus_. _c. moneta_ (plate ) is very common. the generic characters are, shell univalve, involute, obtuse, smooth; aperture linear, the whole length of the shell; effuse at both ends, toothed on each side. "look carefully at those three shells: do you perceive much resemblance between them? 'not much, if any,' you reply, yet they are all of the genus _bulla_. here is _b. lignaria_, _b. terebellum_, (see frontispiece,) and _b. naucum_. (plate .) there are other forms, as the _b. ovum_, _b. volva_, the first somewhat like a cowry; but it is toothed only on one side of the aperture; the second has two long beaks. "this genus is confessedly ill-determined. _b. naucum_ and _b. ampulla_ are examples of the common characters of the genus. the species are sixty-one. [sidenote: voluta. buccinum.] "_voluta_ is also a large genus, containing one hundred and eighty-six species. shell univalve, aperture without a beak, and somewhat effuse; columella _plaited_. this latter character we meet with for the first time. here is the common _voluta_. (plate .) the genus has been much diminished by forming other very striking genera out of it, as i shall soon show you, under the names of _mitres_, _olives_, _gondolas_, &c. _voluta musica_, the music-shell, is remarkable, and not at all rare. "_buccinum_ is another large genus. the shell univalve, spiral, gibbous; aperture ovate, ending in a canal turning to the _right_, with a short beak; pillar-lip expanded. species, one hundred and seventy-two. "you must recollect that when the apex of the shell is turned _downwards_ the canal turns to the right, when it is turned _upwards_ the canal will be to the left hand. my example is _buccinum reticulatum_, a very common species upon our own shores." (plate .) "is not this genus reduced by other authors?' asked charles. "greatly," replied mr. elliot: "you will meet with tuns, helmets, harps, and needles. species of the _buccinum_ genus are found in the african, american, indian, european, and southern oceans. eighteen occur upon our coasts. [sidenote: strombus. murex.] "_strombus_ contains forty-four species. shell univalve, spiral, aperture much dilated, the lip expanding, ending in a canal inclining towards the left. "you must notice the sinus in the outer lip, near the base of the shell. _strombus gigas_, the west indian conch, is very large. some species have the lip ending in claws. _strombus pes-pelicani_, the pelican's-foot, has four palmated claws: (plate .) it is a british shell. the city of santa cruz, in america, is paved with the shells of _strombus gigas_. "the genus _murex_ is both large and beautiful. shell univalve, spiral; aperture oval, ending in a straight canal. "these shells are of very unequal form; their surfaces frequently covered with spines, knobs, or foliations. some are remarkable for the great length of the beak, (frontispiece,) such as the woodcock, the snipe's-head, and venus's-comb. the _murex_ before you is foliated. (plate .) the species are one hundred and seventy-one. several are found on british coasts, but they are not remarkable for beauty. "the top-shell, _trochus_, is univalve, conic, spiral; the aperture either angular or rounded; columella oblique: some of the apertures have a tooth-like projection. (plate .) species, one hundred and thirty. several kinds occur in britain. new zealand, friendly isles, red sea, and most other seas, afford the various species. two of this genus have the power of collecting parts of shells and other testaceous substances, which adhere strongly to the whorls of the shell: it is called the conchologist. the other, named mineralogist, is loaded with stones, pebbles, ores, &c. when heavily laden they are considered rarities. [sidenote: trochus. turbo. helix.] "there is a great similarity between the genera _turbo_ and _trochus_. you must observe the generic distinction carefully. shell univalve, spiral; aperture contracted, orbicular, entire. the one hundred and sixty-seven species have been much divided by other writers. the golden-mouthed _turbo_ is a very fine shell. this genus also contains the common periwincle, an inhabitant of most european shores. sailors report that if the animal is seen creeping high up the rocks, it foretells stormy weather. _turbo muricatus_ is a pretty shell." (plate .) "now we can tell the next genus," said lucy. "_helix_, snail. but what a number of different shapes, father, those shells have! they are not all snails, i should think, that you have placed on the table." [illustration: plate .] "according to linnæus they are all of the genus _helix_, which contains two hundred and sixty-seven species. many kinds are land-shells; others live in fresh water; few inhabit the sea. "shell univalve, spiral, brittle; aperture contracted, semi-lunar, or roundish. the common snail is well-known to most persons. _helix nemoralis_, the wood-snail, is very pretty; sometimes it is pink, with brown bands, or plain yellow, or yellowy banded with brown. (plate .) the greater part of this genus consists of shells remarkable for their thin, brittle, and semi-transparent substances. [sidenote: nerita. haliotis.] "the _nerìta_ genus is very pretty: (plate .) the texture of the shell is in general much thicker than that of _helix_. the shell is spiral, gibbous, pillar-lip transversely truncated, flattish. seventy-six species. _nerìta polìta_ is a handsome species: those most valued are from the south sea. "we have now lost sight of the pillar-lip, and in the genus _haliòtis_ we find a flat, ear-shaped shell, the spire nearly hidden, the disk perforated lengthways with pores. species twenty-one. the animals that inhabit the ear-shells fasten themselves so firmly to the surfaces of rocks, that much force is needful to disengage them: during the fine nights of summer, the animal feeds on the herbage that grows on the sea-shore. the sea-ear from new zealand, and that from california, are superb shells of considerable size. the british species, _haliòtis tuberculàta_, is not uncommon. (plate .) without a regular spire: genera. [sidenote: patella. dentalium. serpula.] "you are well acquainted with _patella_, the limpet: one species of this genus is very common on the rocks by the sea-side. (plate .) in the _patella_ genus we lose sight of a spire; the shell is nearly conic, and shaped like a basin. the species are very numerous, exhibiting great variety of form; the number is two hundred and forty. "the form of _dentalium_ is easily known. the shell is univalve, nearly straight, tubular, not chambered, and open at both ends. "the species called elephant's-tooth is slightly curved, the colour green, (plate .) it is found in the european and indian seas. there are only twenty-two species. _dentalium entails_, the dog's-tooth, is very common. "the _serpula_ genus is remarkable. the shells are tubular, frequently closed at one end. they are often found in clusters, adhering to rocks, stones, fuci, shells, &c. "there is _serpula triquetra_ upon a _pecten_, (plate .) [sidenote: teredo. sabella.] "from the appearance of this piece of timber you may form some idea of the devastation committed by the _teredo_, or ship-worm. (plate .) the shell is tubular and flexuose; two valves at each end, and penetrating through wood. there are four species. [illustration: plate .] "_sabella_ is the last genus, and a very remarkable one. the species are twenty-five, several of which are british, (plate .) "shell tubular, formed of sandy and calcareous particles, agglutinated, and inserted in a membranous sheath. _sabella belgica_ is found in britain. _s. chrysodon_ is found buried in sea-sand, often several inches long; it is covered with fragments of shells, and so brittle that it is not easy to obtain a complete specimen. "we have now finished our linnæan genera, and here we must pause for the present. if you wish for any assistance in your study of the thirty-six examples that i have given you, i shall be ready to afford you both any help that lies in my limited power." chapter vi. [sidenote: system of lamarck.] "lucy and i have been collecting a variety of species," said charles to his father, "since our last lesson in conchology. we have also seen several large collections of shells, one of which was arranged according to lamarck. i was much pleased with the new genera taken from _buccinum_, _bulla_, _turbo_, and others. "we are desirous of gaining information on this new system, if you can spare a little time to attend to us." "willingly," replied mr. elliot; "i anticipated such a request, and have been making lists of the genera belonging to each system; so that, upon meeting with a new genus, you may be able to ascertain with some accuracy its place in the old arrangement. "lamarck founds his system upon the structure and form of the animals, so far as they have been ascertained, and with which the exterior, or shell, must necessarily coincide. the conchology occupies the three last _classes_, and _one order_ of another class, in the well-known work which i have before mentioned to you. [sidenote: annularia. sedentaria.] "to begin with the rd order of the th class:-- class, _annularia_. order, _sedentaria_, annulated worms. lamarck. linnæus. _siliquaria_, taken from _serpula_. _dentalium_, ---- _dentalium_. _pectinaria_, ---- _sabella_. _sabellaria_, ---- _sabella_. _spirorbis_, } _serpula_, } ---- _serpula_. _vermilia_, } _galeolaria._ _magilus._ "there has been much variation in the opinions of naturalists respecting the proper place of genus _dentalium_. cuvier, a very celebrated writer, agreed nearly with lamarck; but still more recently it has been considered as nearest to a new genus, _fissurella_, (_patella_.) the fossil-shells are found in london clay in great numbers; in the marle at folkstone, &c. "_spirorbis._ all the species are minute, fixed upon sea-weeds, and other marine substances. the animal which inhabits them is of a deep red colour. "_galeolaria_ is a new holland genus. "_magillus_ is found in the isle of france; the shell is sometimes three feet in length. * * * * * [sidenote: cirrhipeda--first order.] "class th. _cirrhipeda_, contains two orders: the first, _sessile_, or placed upon some other body; the second, _pedunculate_, and fixed at the extremity of the pedicle to other substances. "the class takes its name from the _cirrhi_, or feathery tentacula. the genus _lepas_ only is contained in the _cirrhipeda_ class. * * * * * " st order. shells sessile. genera. _tubicinella._ } _coronula._ } _balanus._ } _acasta._ } all included in _lepas_. _creusia._ } _pyrgoma._ } "the first genus contains but one species; the shell is buried up to its aperture in the skin and fat of whales. "the second, _coronula_, is found inserting itself in the sea-turtle, &c. "_balanus_ is known to you as the acorn-shell; a genus widely diffused; abounding on rocks, shells, and wood, in large colonies. [sidenote: cirrhipeda--second order.] "_acasta_ is found upon sponge. "for examples of _creusia_, we must examine our _madrepores_, and other corals; the shells of this genus are either affixed or buried in them. "_pyrgoma_ likewise adheres, or penetrates into corals. "in the 'penny cyclopædia,' under the word _cirrhipeda_, you will find much useful information, and some plates that will give you a good idea of this class. in the british museum you may see many of the species, and may thus make yourselves familiar with them. * * * * * " nd order. shells pedunculated. _pentalasmis_, (_anatifera_.) } _pollicipes_. } _lepas._ _cineras._ } _otion_, ear-barnacle. } "we have already noticed _pentalasmis_, or barnacle, (plate .) the generic name is changed by later writers; so are those of the two last. "_pollicipes_ resembles _pentalasmis_, with a shorter pedicle, which is rough. the natives of goree are said to eat a large species of _pentalasmis_." "i think we shall not fail to recollect the _cirrhipeda_ class," said lucy; "the forms of the shells are remarkable: and those that live on _madrepores_ i shall search for immediately; but what a number of new genera are taken from the single one of _lepas_!" [sidenote: explanations.] "since the time of linnæus," replied mr. elliot, "many more observations have been made upon the shells that he had examined; many new shells, both genera and species, have been found; and there is little doubt that, if linnæus had now been living, he would have found his own genera inadequate, and would have established new ones. i fear you will have to regret the opposite extreme, and complain of the multiplicity of new genera, and new names. our object is to become familiar with the shells, and by knowing the linnæan name, and that bestowed by lamarck, two authorities very generally cited, you may understand what species is alluded to by modern conchologists. the names of bruguieres, leach, gray, and sowerby will often occur among many others. "for example: let us take the plate of a remarkable multivalve; you find that it is named _scapellum vulgare_, and that it is so called by leach. below, you find '_pollicipes scapellum_, lamarck;' and on referring to our comparative lists we find that the shell was a _lepas_, (_l. scapellum_ of linnæus.)" [sidenote: explanations.] "but they have kept the specific name," observed charles. "and made it the generic," said mr. elliot; the peculiarities and variations are deemed insufficient to found a new genus. "here we shall pause for the present; and then proceed to the th class." chapter vii. eleventh class.--_conchifera._ two orders.-- st. _bimusculosa_, two muscular impressions. nd. _unimusculosa_, one muscular impression. [sidenote: conchifera, shell-bearers.] "this class," observed mr. elliot, "contains all the bivalves of linnæus, and some genera taken from the univalves and multivalves. "the animals of this class are _shell-bearers_ or _carriers_, they remain constantly fixed in their habitations: the body is fastened to the shell by one or two strong muscles: when the shell is vacant we find the _cicatrix_. refer to your explanation of terms, and you will find the word. "the body is soft, without joints, without head or eyes; it is wrapped in a mantle or tunic. the mouth, always hidden in the tunic, is merely an opening to admit food, without jaws or teeth. the shell is always bivalve; the valves united by a hinge or a ligament; sometimes there are accessory pieces to the valves. [sidenote: conchifera. unimusculosa.] "some of the _conchifera_ are furnished with a kind of foot, which enables them to move with their shells, to draw out fibres by which they fasten themselves to marine bodies. the muscles that fasten the animals to their shells are thick and strong; their use is, to close the valves by contracting; when the muscle is relaxed, the elastic ligament is sufficient to open them. the _conchifera_ are all aquatic; some inhabit fresh water, the others dwell in the sea. "the class contains nineteen families and two orders. the first order, _bimusculosa_, contains thirteen families. the first includes genera that you will scarcely expect to find among the bivalve shells. * * * * * " st family, _tubicolaria_, contains, _aspergillum_, watering-pot _serpula._ _clavagella_ ------- _firtuluna_ _septaria_ _serpula._ _teredina_ fossil genus. _teredo_ _teredo._ "_aspergillum javanum_ is a rare and curious shell from the indian seas, (plate .) the whole family is remarkable, and was referred, you perceive, to a very different order. _clavagella_ was till lately considered as existing only in a fossil state. the researches of recent travellers have discovered _clavagella_ at port jackson, in australia.[a] there is a specimen in the british museum. the valves are enclosed in the tube. [a] see penny cyclopædia, article clavagella. "the valves of _teredo_ are noticed as forming part of the linnæan generic character, you will recollect. lamarck considers them as true _conchifera_. in many specimens of _teredo_ the valves are wanting, and the tube only remains. * * * * * [sidenote: pholadaria.] "the family _pholadaria_ contains, _pholas._ _pholas_, stone-piercer. _gastrochæna_ _pholas_ and _mya_. "notwithstanding the accessory pieces of the hinge, _pholas_ is placed among bivalve shells, the essential character of which is to have two valves united by a hinge. the _pholas_ has a foot or strong muscle, very thick and short. in the next genus, composed of _pholas hians_ and _mya dubia_ there are no secondary valves. "allied to this family is _xylophaga dorsalis_, a curious shell. one specimen has been lately found at gravesend, upon a stick. * * * * * [sidenote: solenacea. myaria. mactracea.] "_solenacea_ includes _solen_ _solen._ _panopæa_ _mya._ _glycimeris_ _mya._ "the _solen_ is furnished with a muscle, called by some writers a tongue. by the aid of this instrument they descend two feet deep in the sand. the tongue is first projected from the shell, and cuts a hole. it then assumes the form of a hook, and draws down the shell into the hole. this operation is repeated until the shell disappears. _panopæa_ is a large shell--it is in the museum. * * * * * " th family, _myaria_. _mya_ _mya_, or gaper. _anatina_ _mya._ "the animal of _mya_ has also a foot: it buries itself in the sand. you know the broad tooth of the _mya_ genus. _anatina_ has a tooth on each valve. * * * * * "second section contains four families. "_mactracea_ has the following genera: _lutraria_ _mactra._ _mactra_ _mactra._ _crassatella_ _mactra_. _erycina_ ---- _ungulina_ ---- _solenomya_ _mya_. _amphidesma_ _tellìna_. "_crassatella_ is a genus from the seas of new holland. the shell is very thick, with a brown epidermis. a fossil species is found at hordwell cliff. there are several species also found in the chalk. _mactra_, _lutraria_, and _erycina_ are found in a fossil state. _crassatella sulcata_ is common in london clay. * * * * * [sidenote: corbula. lithophaga.] "the family _corbula_ contains two genera. _corbula_ ---- _pandora_ _tellìna_. "_corbula_ comes chiefly from the asiatic seas. there is _one_ species, formerly _mya inequivalvis_, from the british ocean; fossil species several. _pandora rostrata_ is british, and is said to be met with at weymouth. it is a pretty shell. the ligament of these is internal. * * * * * "_lithophaga_ includes _saxicava_ _mytilus_. _petricola_ _venerupis_, or venus of the rocks. [sidenote: venerupis perforans. psammobia.] "these genera consist mostly of small shells, inhabiting stones, into which they bore holes. _s. rugosa_ is british. _venerupis perforans_ is found on our coasts in stones. the valves of these shells have no accessory pieces like _pholas_. * * * * * "_nymphacea_ is the next family, containing, in the first section, _sanguinolaria_ _solen_. _psammobia_ _tellina_. _psammotæa_ ---- "in the genus _psammobia_ we find our _tellina feroensis_. (plate .) the shells of this and the preceding genus resemble the solens in a trifling degree, being a little open at the sides. in form they are near _tellina_, but have not the fold on the anterior valve, but an angle on _each_ valve. the ligament is exterior. * * * * * "in the second section are-- _tellina_ _tellina_. _tellinides_ _tellina_. _corbis_ _venus_. _lucina_ _venus_ and _tellina_. _donax_ _donax_. _capsa_ _donax_. _crassina_ _venus_. [sidenote: corbis. lucina. capsa. cyclas.] "there is but one species of _tellinides_ from the island of timor. the genus _corbis_ is fossil, with one exception, _corbis fimbriata_, from the indian ocean. _lucina_ is a pretty genus of shells. _l. carnaria_ is frequently found in collections. the interior of the valves is of a deep red colour: the muscular impressions are very distant from each other; one is greatly lengthened out; the valves delicately striated. _capsa_ is taken, you perceive, from _donax_. "_tellina_ is found fossil on the borders of the red sea, also in the county of york. of _donax_ and _mactra_ the fossil species are few. "in the third section of this order we find six families. st. _conchæ_, which are of two kinds, fluviatic, living in fresh-waters; and marine, or living in the sea. of the first are, _cyclas_, taken from _tellina_. _cyrene_, partly from _tellina_ and _venus_. _galathea_, _venus paradoxa_, (one species.) "_cyclas rivicola_ (plate .) will give you an idea of this genus: it is _tellina cornea_ of linnæus. the species are very common in lakes, rivers, and ponds: it abounds in river-sand, from which you may often procure perfect specimens. lamarck observes that it is rare in france; but appears common in the thames. [illustration: plate .] [sidenote: potamophila. astarte. pullastra.] "_cyrene_ is a foreign genus. "in the _conchæ marìnæ_ the genera are very numerous. they are all assembled under the _venus_ of linnæus. lamarck reduced the genus; but it has been yet further divided by later writers. _cyprina_, } _cytherea_, } from _venus_, lamarck's genera. _venus_, } but _pullastra_, _astarte_, _venerupes_, and _potamophila_ have been since withdrawn from the original genus. * * * * * "_pullastra_ was the name of a species, and includes _v. pullastra_, _v. papilionacea_, _v. decussata_, _v. litterata_, _v. virginea_. "_astarte_ includes some british species, _v. scotica_, &c. [sidenote: venus. cytherea. isocardia.] "_potamophila_ is a scarce river-shell from ceylon. some species have also been brought from congo by african travellers. the form is triangular, very thick, covered with an olive-green epidermis. lamarck's two genera have been still further reduced; but i shall refer you to the museum for their new names. observe, in _venus_ there are three cardinal teeth, close together, on each valve, with divergent lateral teeth. _v. lamellata_ is rare and beautiful, from the seas of new holland. there are many species of _venus_ in a fossil state. in _cytherea_ we find four cardinal teeth on the _right_ valve, three of them near together, the fourth quite apart. the _left_ valve has three cardinal teeth. _c. dionè_, the thorny venus, is a pretty shell with spines. you may easily procure it. "_astarte_ has some fossil species in the crag and green sand: _a. obliquata_ is one species. "_venericardia_ is wholly a fossil genus: one species is found in the crag, _v. senilis_. * * * * * "the family _cardiacea_ contains _cardium_ _cockle_ _cardita_ _chama_ (some species.) _cypricardia_ ------ _hiatella_ _mya_. _isocardia_ _chama_. "_isocardia cor_ is british. (plate .) there is a beautiful species, _isocardia moltkiana_ from the east indies, which is much valued by collectors. * * * * * "in the family _arcacea_ we find, _cucullea_ _arca_. _arca_ _arca_, ark-shell. _pectunculus_ _arca_. _nucula_ _arca_. [sidenote: arca. pectunculus. nucula. nayada.] "the hinge of _arca_ in this arrangement is always _straight_, furnished with a number of teeth; the ligament is external. the shells are open at one end, for the animal throws out at the aperture a number of threads, by which it fastens itself to the rocks. the species are thirty-seven, and also several fossil. "the orbicular form of _pectunculus_, and its arched hinge, distinguish this genus from the preceding one. they are allied to the pectens by their form, and their crenulated internal margin. "the hinge of _nucula_ is set with little teeth on each side, like a comb. it is pearly within, and sometimes small pearls are found in the shell. _pectunculus costatus_ is found in london clay. "_trigoniana_ is a small family containing _trigonia_ and _castalia_. the first is a fossil genus chiefly. some species are found in the portland stone, or oölite beds. "the next family contains the _nayada_, chiefly composed of fluviatic, or fresh-water shells. they are covered with an olive-brown epidermis, which is constantly found eroded, or destroyed at the beaks. the muscular impressions are lateral and much separated; one of them is formed of two or three distinct irregular impressions. _unio_, taken chiefly from _mya_. _hyria_ _mya_. _anodon_ _mytilus_. _iridina_ very rare genus. [sidenote: unio. anodon. diceras.] "_unio_ has two teeth on each valve; one is cardinal, the other lengthened out. the ligament is exterior--the shell pearly. _unio pictorum_ is common in rivers. the shell is used to hold small masses of gold or silver for artists, under the name of _shell-gold_. "_anodon_ is also to be met with in our rivers. "_a. anatina_ is eaten by ducks and crows. the latter, when the shell proves too hard to penetrate, mount with it into the air, and letting it fall, pick out the fish from the broken shell. * * * * * "_chamacea_ has only three genera. _diceras._ _chama_ _chama_. _etheria_, a rare genus, from the indies and madagascar. * * * * * "_diceras_ is a fossil genus--only two species known according to lamarck. [sidenote: chama.] "linnæus had assembled in his genus, _chama_, shells with equal and with unequal valves, shells fixed to other marine bodies, with those that are free; some with _one_, others with _two_ muscular impressions. in the present genus, _chama_, the shells are irregular, thick, scaly, or spinous. the hinge has one thick tooth, often notched: the beaks are bent inwards. they are found in the indian, american, and mediterranean seas. there are several fossil species. "the first order, _bimusculosa_, is finished. in our next lesson we shall proceed to the families and genera contained in the second, _unimusculosa_." chapter viii. [sidenote: unimusculosa. tridacna. modiola.] class.--_conchifera._ second order.--_unimusculosa._ " st family, _tridacnacea_. _tridacna_ _chama_. _hippopus_ _chama_, (one species.) "in the first genus we find the great _tridacna gigas_, the largest and heaviest shell yet known. it sometimes weighs five hundred pounds. the hinge has two teeth, the lunula is open, the valves equal, the ligament exterior. * * * * * "_mytilacea._ _modiola_ _mytilus_. _mytilus_ _mytilus_. _pinna_ _pinna_. "the greater part of these genera attach themselves to marine substances by a byssus. the _modiola_ genus are rarely found fixed. the ligament internal, lodged in a marginal gutter. beaks nearly lateral; hinge without teeth. the genus _pinna_ is unaltered. small crustaceous bodies, resembling the crab, are sometimes found in the shells of the _pinna_. * * * * * [sidenote: pinna. perna. avicula.] "_malleacea._ _crenatula_ rare and little known. _perna_ _ostrea_. _malleus_ _ostrea_, hammer-oyster. _avicula_ _mytilus_. _meleagrina_ _mytilus_. "the first genus is found in the seas of warm climates. the shells are thin and foliated. the hinge of _perna_ differs widely from that of the oyster. it is linear, formed of sulcated teeth. there is a sinus under the extremity of the hinge, for the passage of the byssus. compare _p. isognomon_ with the common oyster, and you will find few points of resemblance between them. (plate .) _perna ephippium_ is also a curious species, very pearly within. the _hammers_ are rugged and singular in form. they are all foreign, from the oriental seas. "_avicula_, or swallow, so called from the resemblance of the shells to a bird flying, was considered as a single species by linnæus. lamarck makes eighteen species in his new genera. _meleagrina_ has two species. the pearl-bearing muscle, as it is called, is found in the persian gulf, the gulf of mexico, &c. the interior of the shell is coated with thick pearl, and within it are formed those globular substances known by the name of pearls. * * * * * [sidenote: meleagrina. lima. pecten.] "family, _pectenida_: genera-- _pedum_ only species, from india, rare. _lima_ _ostrea_. _plagiostoma._ _pecten_ _ostrea_, scallop. _plicatula_ _spondylus_. _spondylus_ _spondylus_, thorny-oyster. _podopsis._ "the genus _lima_ is longitudinal, auricled, or eared; hinge without teeth, with a hollow receiving the ligament. these are very pretty shells, generally white, almost transparent, resembling the _pecten_. _lima_ comes from the american seas, and is a species easily obtained. there are also several fossil species. "_plagiostoma_ is wholly a fossil genus, of which several species are found in this country, in lias, &c. "the pectens are so easily known that i need only mention some fine species, such as _p. pallium_, a splendid shell, from the indian seas: _p. pleuronectes_ is a finely polished, smooth species from the indian ocean. "the genus is divided into sections, viz. ears equal, ears unequal. you may find some common species on our own shores, and you may procure fossil species: they are numerous. [sidenote: plicatula. ostrea.] "_plicatula_ is a genus taken from _spondylus_. _spondylus gæderopus_, from the mediterranean, is a common shell in collections. "_podopsis_ is a fossil genus. "_ostracea._ "the oysters and pectens differ so widely that they do not even rank in the same family. * * * * * "in the _ostracea_ are, _gryphæa_ _ostrea_. _ostrea_ the same. _vulsella._ _placuna_ _anomia_. _anomia_ the same--antique lamp. "there is but one recent species of the first genus; but many fossil. "the oyster is said to possess the most limited faculties of all shelly tribes. immovable upon the rock or marine substance to which it is fastened, it receives no other nourishment than what the waves contribute, and indicates no other sign of life than opening and closing the valve of the shell. this genus still retains a great number of species: one section has the margin of the shell either _simple_, or _waved_, the other _folded_. _o. edulis_, common oyster, belongs to the first division. "_o. folium_ is of the second; a curious species, from the indian and american seas: the shell is fixed to wood and to the roots of trees on the sea-shores. "_vulsella_ is a foreign genus, from the indian and other seas. [sidenote: placuna. anomia.] "_placuna_ does not adhere to any marine substance. the valves are flat, thin, and transparent; the very small space between them shows that the animal must be extremely flattened: there are two singular ribs at the hinge in the form of a v. "_p. placenta_, chinese window-glass, is so transparent when young, that it serves instead of that material in china. "_anomia._ the shells of this genus are fixed, like the oyster, to marine bodies. they live and perish on the spot where they are at first produced. i have noticed the muscle by which they attach themselves. lamarck informs us that a hard, small operculum is to be seen at the extremity of this muscle, and fills up the _hole in the flat valve_ when the muscle is contracted. (plate .) "the family _rudista_ contains only a few genera, which will be quite uninteresting to you at present. "the next, _brachiopoda_, has _crania._ _orbicula_ _patella_. _terebratula_ some from _anomia_. _lingula_ _patella_." lucy could not forbear interrupting her father upon hearing the name of _patella_. "how can that genus be mixed with the _conchifera_?" she inquired. "the shell is _bivalve_," he replied; "raised upon a fleshy peduncle, and fixed to marine substances; the hinge is without teeth, having the form of a duck's beak; the colour a greenish tint. it is found near the molucca isles. [sidenote: hipponyx mitrata.] "yet more remarkable is the _hipponyx mitrata_, a common shell, known as _patella mitrata_, long supposed to be a univalve, the upper valve only being known. a french naturalist discovered the lower valve, and _both_ have one muscular impression in the form of a horse-shoe. "i think that it will be best to pause a little before we enter upon the study of the twelfth class, _mollusca_, which contains most of the univalves of linnæus." chapter ix. [sidenote: mollusca. cleodora.] twelfth class--_mollusca._ "as i have observed that you have been very diligent in studying lamarck since our last lesson," said mr. elliot, "i propose to make you acquainted with the variations in the univalve genera. "the animals of the _mollusca_ are soft, without joints, generally possessing a head, eyes, and tentacula, or feelers. they have also a fleshy membrane, called a foot, which they use for climbing. the orders, excepting the first, are named from the position of this foot. they are five in number. the first order contains very few genera. one genus, named _cleodora_, contains a species brought from africa. the shell is curious, transparent, and shaped like the head of a halberd. "the animals of the second order, _gasteropoda_, have a muscular foot, or disk, on which they rest. the families are seven. the first, _tritonia_, i shall pass over. "_phyllidiana_ includes the genera-- _phyllidia._ _chitonella._ _chiton_ coat of mail. _patella_ _patella_, or limpet. [sidenote: chiton. patella.] "the _chiton_ moves like the _patella_, upon a disk, or foot. "the body of _patella_ is entirely covered by the shell. you may have many opportunities of examining the british species. _p. pellucida_ is very transparent, with blue lines. * * * * * "the family _semi-phyllidiana_ contains _pleurobranchus._ _umbella_ _patella_. "the _umbella_ shell is flat and white, and is sometimes four inches in diameter. it is common in the isle of france: there is another from the mediterranean. * * * * * "_calyptracea_ is a larger family: it has many genera taken from _patella_: _parmorphorus_, thracian-shield. _emarginula_, } _fissurella_, } _pileopsis_, } _patella_. _calyptræa_, } _crepidula_, } _ancylus_, } [sidenote: fissurella. pileopsis. bulla.] _parmophorus_ is found in the seas of new holland and new zealand. the margin of the next genus is distinguished by a slit: the shell is conic. (plate .) _fissurella_ has the top of the shell perforated; it is called the _key-hole_ limpet, from the shape of the aperture. _pileopsis_ is obliquely conic. it was with this division that the curious _hipponyx_ ranked. "_calyptræa_ is very thin and brittle, with an internal lip. (see frontispiece.) "_crepidula_ has the shell partly covered, or arched: it looks like a little slipper. "_ancylus spina-rosa_ is a pretty species from the south of france: the genus is fluviatic. _a. lacustris_ and _fluviatilis_ are both natives of our fresh-waters. * * * * * "the next family, _bullæana_, has _acera_ _bulla_. _bullæa_ _bulla_. _bulla_ the same. "_acera_ and the following genus have each but one species, _bulla carnosa_ and _b. aperta_ of linnæus. the original genus _bulla_ was composed of an assemblage of shells of various characters, having little resemblance except in their gibbous form. _bulla naucum_ is an example of the genus of lamarck's system; so is _b. lignaria_. (see frontispiece.) _b. ampulla_ and _b. striata_ are common in collections. * * * * * [sidenote: aplysia. dolabella.] "_aplysiana_ is a small family, containing _aplysia_, or sea-hare. _dolabella._ "one species of _aplysia_ is found on the devonshire coast: the name sea-hare marks the singularity of the two tentacula, which resemble the ears of the hare. the body is folded up in a loose skin, or mantle: upon the middle of the back it carries a circular shield, thin, transparent, and yellowish, in which it resembles the slug. these animals swim with ease. "_dolabella_ resembles the _aplysia_ in some degree; the genus is foreign, and one species is known to inhabit the bays of the isle of france, where it covers itself with a portion of mud." "i cannot understand why animals related to the slugs should find a place here," said charles. "have not slugs the characteristics of the _mollusca_ class?" asked his father. "and are you quite sure that they are without a shell? [sidenote: onchidium. limax.] "our next family, the _limacina_, has _onchidium._ _parmacella._ _limax_, slug. _testacella._ _vitrina._ "_onchidium_ is a genus from the shores of the indian seas. the animals have a shield: they live near the sea, and some are known to swim, often coming to the surface to breathe the air. "_parmacella_ was found by an english traveller in mesopotamia. it has a shell covered by a shield. but you have not answered my question respecting the _limax_, or slug." "i do not recollect," replied charles; "yet how often we see slugs!" "if i may be allowed to answer," said lucy, "i think that the slug has what i now understand to be a _shield_. i have often watched the animal contract itself, and seen a broad, flat piece upon the back, which i thought was a kind of shelter for it." "the _limax_, or slug," continued mr. elliot, "is, in fact, provided with a coriaceous escutcheon, or shield, beneath which the animal partly conceals itself. the _limax agrestis_, or spinning-slug, has the power of suspending itself by a kind of thread, formed of the viscid substance that covers the body. [sidenote: testacellus. colimacea.] "_testacellus_ is a very interesting genus, lately found in england: the animal has a resemblance to the common slug: it carries the shield on the hinder part of the body. "_testacellus scutellum_ feeds on earth-worms, and can so much lengthen the body that it follows them under-ground. "our next order will show great alterations in the very large genus _helix_. i shall name to you those of lamarck. "the third order of _mollusca_, _trachelipoda_, begins with a well-known genus, the snail, _helix_. the term signifies that the _foot_ is situated under the neck, or anterior part of the body. the families in this order are numerous: they are divided into two sections; the first includes those that breathe only in the air; the second those that can exist only in the water, and are furnished with a syphon. * * * * * [sidenote: helix. curocolla. anostoma.] "first section: family _colimacea_; genera numerous; animals live upon land only; tentacula generally four; during winter they enclose themselves in their shells, with a false operculum. _helix_, snail _helix_. _carocolla_ _helix_. _anostoma_ _helix_. _helicina_ _helix_. _pupa_ _helix_. _clausilia_ _helix_. _bulimus_ _helix_. _achatina._ _succinea_ _helix_. _auricula_ _voluta_. _cyclostoma._ "what a number of new genera!" said lucy. "i see the forms of the shells vary very much; and how beautiful these little transparent shells are!" "they will find a place shortly. here is a well-known species, _h. aspersa_, in most of its varieties; _h. pomatia_, the apple-snail, now naturalized in the county of surrey; _h. ericetorum_, white with brown bands, very frequent on chalky soils; _h. citrina_, transparent, pale yellow, sometimes with one dark band; _h. muralis_, from the walls of rome; _h. bidentalis_, from teneriffe; and the little _helix hispida_, which you may search for in your own garden; it is small, dark brown, and rough. "_carocolla_ has the shells more flattened than _helix_. "_anostoma depressa_ is a rare and curious shell. "_helicina_ is a west indian genus. you saw them just now. we shall find helix in two other families. [sidenote: pupa. bulimus. auricula.] "_pupa_ is a curious genus. the shells resemble a chrysalis. a few minute species are found in britain. _p. muscorum_ i have found buried among damp moss. the larger species are natives of tropical regions. these shells are often found _decollated_. "_clausilia papillaris_ is a pretty shell. (plate .) "_clausilia rugosa_ is found in some parts of britain, under old hedges, at the foot of old trees, and similar places. it is a tapering shell, with the aperture reversed, or left-handed, and bi-dentated: the colour red-brown. it is to be found in the vicinity of dorking, in surrey. "_bulimus_ is a large genus. a common small species is the _gaudaloupe bulimus_. "the largest land-shells are found in the genus _achatina_. the greater number are african. "_succinea_ contains a few species. one of them, _s. amphibia_, is common near fresh-water. "_auricula_ has some resemblance to a _voluta_. the aperture is longitudinal: the columella has one or more folds. "the forms of the species in _cyclostoma_ are variable; but the aperture is circular, and the margin revolute, or rolled back. _c. elegans_ is often to be found on hedge-banks or chalk soils. it is a pretty shell, sometimes white, often tinted with purple. "in the family _lymænana_, the species are amphibious; inhabiting fresh-water; but rising to the surface to breathe the air. they have but two tentacula. "as several species are british, you may have the satisfaction of examining them for yourselves. * * * * * [sidenote: planorbis.] "the genera are, _planorbis_ _helix_. _physa_ _bulla_. _lymnæa_ _helix_. "_planorbis_ is a discoid shell, and one peculiarity of the genus is, that they are all reverse shells. in a discoid shell the spire is depressed; when held up, the whorls turn from right to left, and the aperture is left-handed. the largest species is _p. cornu-arietis_,[b] which is a native of brazil. _p. corneus_ is common in ponds and ditches. empty shells are to be found at the edge of the water. (plate .) if you take the animal to examine, and study its habits, remember that you have no right to injure it, and that you have already promised me that no kind of cruelty shall take place. [b] ram's-horn. "_p. vortex_ is a smaller species. the outer valve is carinated. "_physa_ is found in fresh-water upon aquatic plants. they are small shells. [sidenote: lymnÆa. melanopsis. valvata.] "the animal of the _lymnæa_ genus has two flat tentacula. _l. stagnalis_ is a very pretty spiral shell, common in ponds. "_l. auricularia_ is also frequent. it is much smaller than the first species. the last whorl is swelling, and the aperture very wide. they are both thin and brittle. * * * * * "the family _melaniana_ are chiefly foreign. the shells are covered with a dark-coloured epidermis. they are operculated. _melania_ _helix_. _melanopsis._ _pirèna._ "a species of _melanopsis_ inhabits the river orontes, in syria. * * * * * "there is yet another family connected with _helix_, the _peristomata_, containing _valvata._ _paludina_ _helix_. _ampullaria_ _helix_, partly. [sidenote: paludina.] "some of the _valvata_ genus are found in fresh-water in britain and other european countries. the shells are small; they are discoid or conoid, and have an operculum. in the shells of this family the margin of the aperture is carried completely round. in _paludina_ the whorls are convex. they generally inhabit fresh-waters. "_p. vivipara_ is found in rivers. quantities of empty shells may be taken from the sand of the thames. "fossil species abound--petworth marble is full of them." chapter x. [sidenote: neritacea. neritina.] "the family of the _neritacea_," said mr. elliot, as he renewed his lessons to charles and lucy, "are remarkable in their form. their left-margin is truncated, without any appearance of a columella. they possess an operculum, and are either marine or fluviatic. the genera are, _navicella._ _neritìna_ _nerìta_, nerite, or hoof-shell. _nerìta_ _nerìta_. _natìca_ _nerìta_. "you will recollect that the order _trachelipoda_ is still continued. "_navicella_ is a foreign genus from the indian rivers. [sidenote: neritina. nerita.] "_neritìna_ is a pretty genus of shells, from the european, the east and west indian rivers. they resemble the _nerìta_ genus, but are all fresh-water shells; thin, smooth, and variously marked; without any tooth or notch on the right-margin of the aperture. "_n. virginea_ is common in collections; it is marked with various lines and dots. "_n. fluviatilis_ is common in our rivers: you may find plenty in river-sand, of red and brown colours, and various sizes. "_n. zebra_ and _n. meleagris_ are also pretty shells. the little _neritìna viridis_, from the west indian streams, is one of the smallest species, of a pale pellucid green. "_nerìta_ is a marine genus. the shells are solid and semi-globose; the left-margin is truncated, the right-margin toothed, or crenulated. this genus is never umbilicated. "_n. polìta_ is a handsome shell: it is thick, polished, and variously marked; the base of the aperture is yellowish. "_n. peloronta_, the bleeding-nerite, is marked with a crimson spot. "_n. tessellata_ is sulcated, or furrowed, chequered with black and white. "_natìca_ differs from the former genera in these particulars: the shell is umbilicated; the left-margin oblique, not toothed, callous, the callosity sometimes covering the umbilicus. the species are numerous, and several are common in collections. "_n. aurantius_ and _n. millepunctata_ are good shells. [sidenote: ianthina. sigaretus. stomatella.] "_ianthina_ is the last of the snail-like genera. its beautiful purple colour renders the shell a favourite. they are marine, though so fragile and transparent. the animal floats upon the surface of the sea, by means of a vesicular appendage to the foot, which, it is said, may be inflated or contracted at pleasure. _ianthina_ shines by night. _i. communis_ is found in abundance in the atlantic and in the mediterranean. * * * * * "the family _macrostoma_ contains, _sigaretus_ _helix_? _stomatella._ _stomatia._ _haliòtis_ _haliòtis_, sea-ear. "these genera form a beautiful family, and all bear a resemblance to the human ear. "_sigaretus_ is white and pearly; the shell is enveloped in the folds of the mantle belonging to the animal. there are several species, one or two of which were ranked among the _helix_ race. "_stomatella_ is also very pretty; the shells are pearly. _s. auricula_, from new holland, has the appearance of a little _haliòtis_. "_stomatia_ is a small genus. [sidenote: haliotis. vermetus. scalaria.] "with the genus _haliòtis_ you are already acquainted. the animal appears to be very elegantly formed, if the plate i have seen of it be correct. "there is a number of fine specimens in the british museum. * * * * * "the family _plicacea_ contains only, _tornatella_ _voluta_, chiefly. _pyramidella._ "all the species have plaits, or folds, on the columella. the shells are marine and foreign in both genera. (plate .) * * * * * "our next family, _scalariana_, contains the genera _vermetus._ _scalaria_ _turbo_. _delphinula_ _turbo_. * * * * * "the single species of the first genus, _vermetus lumbricalis_, inhabits the sea near to senegal. the shell is tubular, thin, twisted spirally; it is fixed on marine substances by the end of its thin, pointed spire. the shells are usually found in groups. "the genus _scalaria_ is one of the most elegant among univalve shells. the singularity of the numerous ribs renders the shells easily known from all other genera of turreted _mollusca_. the aperture is nearly round, the whorls gibbous, or inflated with carinated ribs: the colour is usually pink or white. it is very costly. (plate .) these shells are brought from the east indies. "the fossil species are very elegant: they are found in the strata above the chalk. "two other species are common, _s. communis_ and _s. lamellosa_. the first is a british species, and is called the _false wentletrap_. [sidenote: delphinula. solarium.] "the shells of the genus _delphinula_ are solid, thick, somewhat discoid, often armed with spines, without any apparent columella. the recent species inhabit the indian ocean. there are several fossil species of _delphinula_. "the _turbinacea_ family contains many genera, with which you will soon become familiar. i believe you are already acquainted with this shell, which, from the time it was first known to collectors, has always been celebrated for beauty. it is now called _solarium perspectivum_. (plate .) the large, spiral, crenated umbilicus is its great peculiarity. the french call the shell _cadran_, _dial_. in its natural state the shell is covered with an epidermis. there are a few fossil species, one in the oölite of our own country. the english name is _staircase trochus_. * * * * * [sidenote: rotella. trochus. turbo.] "the genera of _turbinacea_ are, _solarium_ _trochus_. _rotella_ _trochus_--wheel-shell. _trochus_ _trochus_--top shell. _monodonta._ _turbo_ _turbo_. _planaxis_ _buccinum_. _phasianella_ _turbo_. _turritella_ _turbo_. "the genus _rotella_ contains small, flattened, wheel-shaped shells, common in most collections. they are smooth and polished. "_trochus_ is still a large genus. _trochus marmoràtus_ is a fine species from the indian ocean. there are several handsome species on our own shores. _t. magus_ is one of them; it has a large, deep umbilicus, or perforation; the spire is flattened; the whorls are crowned with tubercles. the _trochi_ of tropical climates are thinner than those of northern latitudes. "when any of these shells are placed upon their _base_, their axis is always inclined: of course they never stand perfectly upright. "there are several fossil species. "the genus _monodonta_ holds a middle place between _trochus_ and _turbo_, differing from the former in the aperture, and from the latter in the columella, which is arched and truncated at the base. they are all marine shells. [sidenote: litorina. turbo. phasianella.] "from the well-known genus _turbo_, a new one has been formed, called _litorina_, which includes all the shells of our own coasts that formerly ranked under _turbo_. consequently we find the periwincle has changed its generic name, and from _turbo_ it is altered into _litorina_. _t. muricata_ is now of the same new genus, _litorina muricata_. (plate .) "_turbo pica_ is a large pearly shell known as the magpie. the golden-mouthed _turbo_ is very brilliant; the aperture appears as if gilded, so fine is the yellow tint. it comes from the molucca isles. _turbo smaragdus_, from new zealand, is a rare and beautiful species of a bright green colour. "_phasianella_ is a beautiful genus of shells, formerly very costly. a small but elegant species is found on our own shores, _p. pullus_, _turbo pullus_ of some authors. the colour is pink. "_phasianella bulimoides_, from new holland, is the largest of the species, and once a very rare shell. "the term _turritella_ will give you an idea of the form of our last genus in the family _turbinacea_. the shells are like _little towers_, with a circular aperture. the older conchologists gave the name of _screw_ to all turreted shells, without attending to the form of the aperture. hence we find screws among _turbo_, _buccinum_, and _strombus_ (spindle). [sidenote: turritella.] "_turritella duplicata_ is a heavy shell, often more than four inches long. it is sulcated and carinated; the colour is yellow-white. _t. bicingulata_ is white, marbled with yellow; the whorls are girded with two ridges. there are several fossil species of this genus in london clay." "i think," said lucy, "that three or four genera have been taken out of _turbo_--_scalaria_, _delphinula_, _litoralia_, and _turritella_, and that _litoralia_ is not lamarck's genus." "you are correct," replied her father, "and indeed so many alterations are continually taking place in the generic names of shells, that i cannot enter into all the niceties of modern conchologists. however, the generic name of a shell, according to linnæus or lamarck, is usually given, therefore i hope you will not be greatly at a loss upon meeting with some apparently unknown genus." chapter xi. [sidenote: ranella. voluta. ovula.] "what is charles drawing from his pocket with a look of so much importance," said mr. elliot, the next time they met. "there is _ranella crumena_, thorny-frog; _ovula gibbosa_, the shuttle; and _voluta musica_, the music-shell," said charles. "oh, who gave you those nice shells?" asked lucy, "and how do you know the names?" "let my father say if i am correct, first," replied charles. "perfectly," answered his father; "but i fancy that i can guess how you obtained your information. you have been buying these specimens, and had the names from the shell-vender. i hope your purchase did not cost much, for they are not rare shells?" "no; i should not choose to spend a large sum, even from my purse, until i am a better judge of the value of shells. but as our collection is but small, i thought that lucy would be glad to see an addition to the stock." [sidenote: canalifera, cerithium.] "thank you, brother," said lucy, "you never forget me in your purchases or your pleasures." "let us return to our subject," said mr. elliot, "and notice the families of the next section, which are all carnivorous, living on animal substances. they have a projecting syphon, which conveys the water to them: they are all marine. the syphon passes through the base of the aperture, either into a canal, or channel, or a narrow, recurved margin. the mouth is furnished with a trunk. * * * * * "_canalifera_ contains in the first section, _cerithium_ chiefly _murex_. _pleurotoma_ _murex_. _turbinella_ _voluta_ and _murex_. _cancellaria_ _voluta_. _fasciolaria_ _murex_. _fusus_ _murex_. _pyrula_ _murex_ and _bulla_. [sidenote: fossil cerithium. turbinella.] "the naturalist bruguieres established the fine genus _cerithium_, mixed by linnæus among those of _murex_, _strombus_, and _trochus_. these shells are always turreted, having a short canal at the base; the aperture oblong, oblique, with a gutter turned backwards. (see frontispiece.) many are girded with zones, that are granulated, or beset with little tubercles. it is remarkable that _cerithium giganteum_, a species more than a foot in length, is found fossil in france, and as a living species in the seas of new holland. _c. telescopium_ is a fine shell from the east indies. _c. vertagus_ is smooth, tawny-white, with a recurved canal. it comes from the moluccas. many species occur fossil in london clay and in plastic clay: the woolwich pits afford specimens, and also of _turritella_. "_pleurotoma_, formerly united with _murex_, is distinguished by the singular _notch_ in the right-margin of the shell. one species, the tower of babel, is well-known, and another is common under the name of _murex javanus_. the fossil species are numerous. "_turbinella_ is taken from _murex_ and _voluta_: some species are thick, heavy shells, from the indian seas. "_cancellaria_ is an elegant genus: the shells are varicose, reticulated, or cancellated; the columella has folds upon it, varying in number, the right-margin sulcated within. there are several fossil species, which are considered very beautiful. "_fasciolaria trapezium_, the persian robe, is a fine shell from the indian seas, very common in collections. [sidenote: fusus. pyrula. ranella.] "the genus _fusus_ consists of spindle-shaped shells, of which _fusus colus_, the distaff, will give an idea. they are covered with an epidermis which conceals, in some species, the fine colours beneath. "_fusus despectus_ (_murex_ of linnæus) is the largest of the british turbinated shells, and very common: it is the large whelk. "_fusus contrarius_, the reverse whelk, is found fossil in the essex crag. "among the shells of the _pyrula_ genus we find _p. ficus_, the fig, placed by linnæus among the _bulla_ race. _p. spirillus_ is a pretty species, with a long canal and a flattened spire, having a tubercle at its termination. * * * * * "second section of _canalifera_: shells with a varix on the right-margin. _struthiolaria_, } _ranella_, } _murex_. _murex_, } _triton_, } "_struthiolaria_, ostrich-foot, is a remarkable shell from new zealand. "_ranella_, thorny-frog, is frequent in collections: there are several species: _r. crumena_ is easily obtained--you must purchase a specimen. [sidenote: murex. triton.] "notwithstanding the great reductions of the _murex_ genus, it is still large, and contains very fine species. the shells have _three or more_ varices upon each whorl; those in _ranella_ but _two_; while _struthiolaria_ has a varix only on the right-margin. the species are numerous, and common in collections. _m. saxatilis_ is white, and zoned with rose-colour or purple. the foliations, or branches, are erect. the rose-bush is pretty; and the wagtail, _m. motacilla_, will, doubtless, be a favourite with you, as well as the scoop, _m. haustellum_. "notwithstanding the resemblance of the genus _triton_ to those of _murex_ and _ranella_, there are permanent differences which make them distinguishable at first sight. i have already noticed the varices of the preceding genera; in _triton_ they never form longitudinal ranges, but are alternate, few, and nearly solitary on each whorl of the spire; these varices are generally smooth and without spines.[c] _triton variegatum_, the marine trumpet, is a large, handsome species, from the asiatic seas. _t. lampas_ and _t. lotorium_ are common. _triton anus_ is very remarkable. [c] lamarck. "in the next family, _alata_, we must notice a remarkable fact: the shells, while they are young, assume a different form to those more advanced in growth. [sidenote: rostellaria. pterocera. strombus.] "the genera are three-- _rostellaria_, } _pterocera_, } _strombus_, wing-shell. _strombus_, } "in the first genus the shells are terminated below by a canal, or pointed beak; the right-margin entire, or toothed, more or less dilated with age, and having a sinus contiguous to the canal. there is a specimen from our own coast, _rostellaria pes-pelicani_, the pelican's-foot: it was _strombus_ of linnæus. (plate .) there are many of this species found in a fossil state. "the _pterocera_ genus is easily known by the digitated, or fingered, appearance of the right-margin. the greater part of the species become very large. here we find the scorpion, with seven digitations, from india; the spider, with the same number, a large and fine shell, also from india. "_strombus_ has a short canal, the right-margin dilated with age into a simple wing, having, at the lower part, a sinus, separated from the canal at the base of the shell. "all the species are natives of hot climates; some attain a very large size, such as _s. gigas_, so frequently seen in shops, and as ornaments in a room. _s. gibbèrulus_ is a pretty little shell; the white, gibbous whorls render it remarkable; the interior of the lip is pink. _s. lineàtus_ has dark lines round the shell. _s. vittàtus_ has a very long spire; the colour is tawny, girded with white: you may easily meet with this species. [sidenote: cassidaria. cassis.] "the family _purpurifera_ is composed of genera taken chiefly from the large linnæan genus _buccinum_. * * * * * "it is thus divided: "first, the genera with the canal ascending, or turned towards the back of the shell-- _cassidaria_, } _cassis_, } _buccinum_, helmets. "_cassidaria_ is not a very common genus; but the helmets, _cassis_, are both numerous and plentiful in most collections. the straight aperture slightly reminds you of a _cypræa_ perhaps, but the short canal, abruptly turned back, is a clear distinction; the right-margin generally toothed; the columella folded, or wrinkled, transversely. "_c. cornuta_, _c. flummea_, _c. arèola_ and _vibex_, are all well-known species, _c. cornuta_ has large tubercles like horns round the tip of the shell. _c. arèola_ is marked with chequers. _c. rufus_, from the moluccas, is a fine shell, with a deeply coloured red aperture. "in the next division the canal is oblique, and directed backwards. [sidenote: nassa. ricinula. purpura.] _ricinula_ _murex_. _purpura_, } _monoceros_, } _concholepas_, } _harpa_, } _buccinum_. _dolium_, } _buccinum_, } _eburna_, } _terebra_, } "to these genera another has been added, called _nassa_, of which _buccinum arcularia_ will furnish an example. the columella has a callosity very evident in the species _pullus_ and _thersites_. "_ricinula horrida_ has a ringent aperture of a fine violet colour; the shell is thick, and covered with large black tubercles. the genus takes its name from a resemblance to the seeds of _ricinus_. "_purpura_ is a large genus: in certain of the species the colouring-matter exists of which the ancients formed their famous purple dye. it is the last genus that offers any appearance of a canal at the base of the aperture. "_p. patula_, the scoop, from the atlantic and mediterranean, has the aperture remarkably dilated, the margin sulcated. "_p. lapillus_ is a common british shell among the chalk-cliffs of the coast; the colour varies, sometimes white, at others yellowish. [sidenote: monoceros. concholepas. harpa.] "i shall describe a species of the singular genus _monoceros_, by which you will scarcely fail to recognise it. "the columella is flattened like _purpura patula_; just within the outer lip is a row of small teeth; but the principal peculiarity is a process, or horn, near the outer part of the lower lip, and close to the canal, from which the genus derives its name _monoceros_, _one-horn_. it is brought from the seas of america. "_concholepas peruviana_, the only species, is also a remarkable shell. the aperture is very large, almost equal to the shell itself; the spire is near the edge; the outside is marked with ribs, or costæ; there are two short teeth on the right-margin. this shell was placed among the _patella_. "the beautiful genus _harpa_, harp-shell, is remarkable for its elevated ridges on the back of the shell, its large aperture, and its fine colouring. they are east indian shells. _h. ventricosa_ is a common species. _h. nobilis_ is very fine, and also _h. costata_. "equally well-known are the tuns, _dolium_, by their globose form, the right-margin toothed, and a canal below. they reach a large size, and are light shells in proportion to their bulk. _dolium galeum_ is sometimes the size of the human head. _d. perdix_ is a choice species. [sidenote: dolium. buccinum. eburna.] "_buccinum_ contains some british species, as _b. reticulatum_, (plate ,) _b. anglicanum_, _b. undatum_, which is very common. in connexion with this species i wish you to know that a marine substance, called by sailors _sea-wash balls_, by others sea-sponge, and extremely common on all our sea-coasts, is the egg-cases of the _buccinum undatum_. the mass is remarkably light, and composed of numerous little cells, each of which has an opening. the colour varies from yellow to white." "i know them well," exclaimed lucy, "how often i have asked the name of those nests, but never could i obtain a reply worth having! and now, father, give me leave to interrupt you a few minutes. what are those black, stiff, marine substances, with a horn-like projection at each of the four corners; they are all hollow, and open at each end, i think, and usually inflated?" "the egg-cases of the scate." "thank you, father, i will examine them again carefully when i am at the sea-side." "the genus _eburna_," continued mr. elliot, "is remarkable from the smoothness of the shells. _e. spirata_, the joppa whelk, has the whorls deeply channelled. (see the frontispiece.) the columella is umbilicated, and has a canal beneath it. [sidenote: terebra. columbella.] "the _terebra_ genus is turreted; very acute at the apex. (plate .) "the family _collumellaria_ is next in order. the _canal_ now disappears at the base of the shell, but there is a slope and folds on the columella. we have reached the large genus _voluta_ of linnæus, greatly reduced by withdrawing the following genera: _columbella_, } _mitra_, } _cymba_, } _melo_, } _voluta_. _voluta_, } _marginella_, } _volvaria_, } "the shells of _columbella_ are of small size; two species are very common in collections. _c. mercatoria_ is a little shell striated transversely; the outer lip is thickened in the middle, and toothed; the columella is plaited: the animal is furnished with an operculum. "_columbella nitida_ is another pretty species, smooth and shining: you may perceive the generic marks if you look closely--two small folds on the pillar-lip, and the swelling, toothed, outer margin. they are all west indian marine shells. [sidenote: mitra. cymba. melo.] "_mitra_ is a large genus, and it is believed that there are three times as many species yet undescribed. the mitres are natives of warm climates, and few are common. the pillar-lip of _mitra_ is parallel, with transverse folds; the base has a slope, but no canal; the margin of the columella is thin and rolled back. _m. episcopalis_, the bishop, is white with red spots; the columella-folds are four. (plate .) _m. papalis_, the pope's-mitre, has five; the upper whorls are broken into a kind of crown. "in _cymba_, the gondola, the spire ends in a tubercle, and scarcely appears; the aperture is wide: they are very pretty shells. "_melo_, the melon, from the indian ocean, is a very fine genus; here the spire is evident. "_voluta musica_ will serve as an example of the genus. the animal is carnivorous. "_marginella_ is an oblong, smooth, and polished shell; its peculiar character is the thickened outer lip; it is a neat, small species, prettily coloured. "_volvaria_ is a cylindrical shell, convolute, the spire nearly hidden; the aperture straight, as long as the shell. there is a fossil species found in london clay. _v. monilis_ is sometimes strung for necklaces. it comes from senegal. [sidenote: ovula.] "the last family of the order _trachelipoda_ is _convoluta_, which contains many very fine genera. "they are the following: _ovula_ _bulla_. _cypræa_ the same. _terebellum_ _bulla_. _ancillaria._ _oliva_ _voluta_. _conus_ the same. "the general characters of this family are the following: "shell without a canal, the base of the aperture sloping, or effuse, the spire compressed, the last volution almost covering the rest. "_ovula_, you will recollect, was formerly confounded with the _bulla_ genus: the form is egg-shaped, the outer lip toothed in one division, smooth in the other; the shells are white and polished, particularly _o. oviformis_, the poached-egg, from the moluccas. "_o. volva_, the weaver's-shuttle, is a rare and highly-valued species. it is nearly globular in the middle, and is terminated at each extremity by a long beak: it comes from the west indies. _o. gibbosa_ is a common species; the shape is oblong, with a ridge in the centre. [sidenote: cyprÆa. trivia.] "you can be at no loss on seeing the shells of _cypræa_, a large and beautiful genus, which remained unchanged for a long time. lately, we find a few of the small species are become a new genus, _trivia_. "the character of the _cypræa_ is a longitudinal aperture, toothed, in the adult state, on each side. the spire is scarcely to be seen. "while the shells are young they have the appearance of a _voluta_ or a cone; the aperture spreads more, and is without teeth. "the individuals of each species pass through three different states: "in the first, the form is very imperfect; it is like a thin cone, and shows no character of the genus; hence young students are perplexed if they chance to have a young cowry in their collection. "in the second state, the shell is still thin, with a _projecting_ spire; but attains its proper form. "in the third, or adult state, the shell is thick, the colours are perfected, and the spire is very nearly concealed. "when the animal becomes too large for its habitation, it has the power of leaving it, and forming a new one.[d] [d] lamarck. [sidenote: cyprÆa.] "the inhabitant of the _cypræa_ shells has two tentacula of a conic form, and finely pointed; the foot discous, and sometimes tongue-shaped. the mantle is two-lobed, with wing-like margins, capable of being turned back over the shell: this mantle preserves the shell from injury when the animal issues forth in search of food. the genus abounds both in the old and new world; but the larger kind chiefly in warm climates. they live on the coast, and are generally found under stones or rolled coral. a very few species are natives of the european seas. "the tiger-cowry is before you; a large and very common species in collections; it also frequently adorns the mantel-piece. there is a remarkable line extending along the back of the shell; at this part the edges of the _mantle_, that i have before noticed, meet: this line is conspicuous in many species. "_c. aurora_ is a costly shell from otaheite and new zealand; the colour orange, with the base and extremities white. it is large, and has been sold for _l._ when a specimen has been obtained without any perforation. the shell is worn by the new zealand chiefs as a badge of honour. "_c. exanthema_ changes its appearance greatly as it advances in growth. while young, three bands extend over the back, which in its adult state disappear, and the fawn-coloured ground is spotted over with numerous white circular marks. [sidenote: cyprÆa.] "_c. mauritania_, the moor, is a fine species, with very black sides, and tawny-yellow back with spots. it is a native of java. "_c. caput-serpentis_, the serpent's-head, has dark sides, with white fauces: the back is covered with net-work colouring: the fauces, you must remember, are the narrow entrances at each end of the shell. "_c. isabella_, the orange-tip, with pale flesh-colour back, and the fauces orange-colour. "_c. arabica_ is a common species in collections. "_c. mappa_ is varied with deep brown or yellow lines and spots: the dorsal line is laciniated. "_c. talpa_, the mole, has the back fawn-colour, with three zones of pale yellow; the base and sides sometimes nearly black. it comes from madagascar. "_c. vitellus_, the fallow-deer, is fawn-colour, covered with small white spots: from the indian ocean. "the wasp, _c. asellus_, is white, with three brown bands. "_c. helvola_, the star-cowry, has the sides dark orange; the fawn-coloured back studded with small spots. it comes from the maldives. "_c. moneta_, the money-cowry, is generally white, sometimes yellow. [sidenote: tÆrebellum. oliva. trivia.] "_c. annulus_, the ring-cowry, has a yellow mark round the top of the shell. the fowl-cowry, _c. moneta_, is used for money by the natives of siam and bengal. "_c. pediculus_ is changed to _trivia_, a new sub-genus from _cypræa_. we find the following characters:--form of the columella internally concave, ribbed; shell sub-globular, cross-ribbed. _t. carnea_, flesh-coloured shell; thin, pure rose-coloured, with very thin, distant ribs; lips whitish: it has sometimes an indistinct dorsal groove. "_trivia europæa_ (_cypræa_ of authors) is a globose shell, ash or flesh-coloured, with three black dots and a whitish dorsal streak; ribs close, rather thick, and whitish; base white; outer lip wide. the variety has the back without spots. _t. pediculus_ has six square dorsal spots; the colour of the shell pale red; ribs rather thick-covered; dorsal line narrow; base reddish. only one species, _c. europæa_ (or _trivia_) is a native of our shores. "there are several fossil species of _cypræa_. "we now pass on to a genus in which there is but one recent species, _terebellum subulatum_, _bulla_ of linnæus. (see frontispiece.) a fossil _terebellum_ is found in london clay. [sidenote: ancilla. conus.] "the _oliva_ genus contains smooth, shining shells, common, and therefore little valued; nevertheless they are beautiful, and of various colours. "the columella is obliquely striated; the aperture longitudinal and straight. the olives were placed by linnæus among the _volutæ_, on account of the striæ on the columella, without regard to the peculiarity of the _canal_, by which the olives are known from all other shells. this canal separates the _volutions_ of _oliva_. many species are prettily marked by nature, others are rendered handsome by polishing. _o. subulata_ is small, and pointed like a mitre. the common olive is white, with brown, waved lines. _o. irrisans_ is ornamented with yellow zigzag lines: it has two brown zones. _o. oriza_, the little rice-olive, is white. "i should have noticed the small genus _ancilla_, formerly _ancillaria_, which is very near both to _terebellum_ and _oliva_. the columella has a varix at the base, which distinguishes it from _terebellum_, and it wants the canal which separates the volutions of _oliva_. "there are several fossil species. "the concluding genus of the third order is very large, and contains rare and costly shells. this is _conus_, scarcely to be mistaken for any other genus except _voluta_, and that only at a first glance. [sidenote: conus.] "the species are covered with an epidermis, sometimes very thick; the spire has various degrees of elevation, sometimes almost flat; the operculum very small and horny. they are natives of southern and tropical seas: the animal is carnivorous: found in sandy mud, at various depths of the ocean. the species are very numerous--lamarck makes recent. some new species have lately been discovered. many of the cones are very beautiful, both in shape and colour, and the genus has been always in estimation among collectors. the _gloria-maris_, _cedonulli_, _ammiralis_, and some others, have been sold at very high prices, and some of the finest of these are now in england. "lamarck makes two divisions: in the first is comprehended the species with coronated spires; the second those with simple spires; the latter division contains far the greater number. "fossil cones occur, in london clay and crag, in england. "no recent species are found upon our own coasts. "_conus hebræus_, the hebrew-cone, is easily known: (plate :) it has a white ground, and square black markings. "_conus virgo_ is white, with a purple base. [sidenote: conus.] "_c. marmoreus_ is a fine shell. numerous species are within reach of your purses, and i do not doubt that you will soon acquire a good collection at a moderate price. you, charles, will find more pleasure in a cone than in a top; and lucy, who never found much pleasure in toys except in taking them to pieces, has always a ready sixpence either for a poor neighbour in distress, or for some harmless pleasure. "we have yet two more orders of _mollusca_ to notice, the _cephalopoda_ and the _heteropoda_. "at our next lesson i shall mention the genera that are most likely to come under your observation, either fossil or recent." chapter xii. [sidenote: argonauta. nautilus.] "so many families of the fourth order, _cephalopoda_, are found only in a fossil state, and which you will not easily meet with, that i shall not consider it needful to give you the whole catalogue," observed mr. elliot to his young pupils at the beginning of the next lesson. "but we are exceedingly interested about fossils," replied charles; "pray do not pass any species that we may be likely to find." "and i," said lucy, "have much wished to ask whether the _snake-stone_ ever was a shell? it is something like a _planorbis_, but heavy and imperfect." "i will answer your question presently," said her father. "tell me what genera remain to be noticed among the univalves of linnæus?" "_argonauta_ and _nautilus_," was the ready reply. "the animals inhabiting these shells are _cephalopoda_. the word indicates the position of the feet, or more properly _arms_ of the animal, which are ranged round the head like a crown. the body is thick and fleshy, contained in a kind of bag, whence the head issues, surrounded by these arms, which vary in different genera. [sidenote: cuttle-fish. belemnite. spirula.] "the common _cuttle-fish_, a native of our seas, will give you an idea of a cephalopode. "in the first family a fossil-shell occurs that is very frequently met with. "family, _orthocerata_; genus, _belemnite_, thunder-stone, or arrow-head. these fossil-shells occur abundantly in the chalk formations. many superstitious notions have been attached to this extinct marine animal: of these you will find an account in the 'penny cyclopædia.' "in the family _lituolita_ we meet with the delicate and remarkable little shell _spirula peronii_, distinct from _nautilus_ by the separation of the volutions: it is nearly covered by the body of the animal. the colour is white; the texture thin and brittle: it has a lateral syphon, the orifice of which is very clearly to be seen as each compartment is taken off. there is but one species; it is found in the southern ocean and the moluccas. the shells are seen floating on the surface of the water when the animal is dead, and are sometimes carried to the shore. (plate .) [sidenote: ammonite. nautilus.] "another family of this order, _nautilacea_, contains, among many other genera, the celebrated _nautilus_. this genus, you are already informed, is distinguished from _argonauta_ by its shells being many-chambered. two or three fossil species have been found in london clay. "among the various fossil-shells abounding in different strata, not known in a recent state, the one most remarkable and frequently occurring is the ammonite, _cornu ammònis_, so called from the resemblance it bears to the convoluted horns of jupiter ammon, in mythological history. this is your _snake-stone_, lucy, a local name, which you had better change for ammonite. various legends are connected with this fossil, of which you may obtain information by consulting the before-mentioned publication. "as you are desirous of studying geology, a knowledge of the ammonites is very requisite, since whole sections of the genus are characteristic of certain strata. "they are nearly allied to the _nautilus_. the species are very numerous; one hundred and twenty according to some authors--two hundred and seventy species are enumerated by others. they occur in europe, asia, and america: they have been found in the chalk with a diameter of three feet. "in the second division of this order the genus _argonauta_ occurs: the shell has been already described, and retains its original name. (plate .) [sidenote: octopus. loligo. sepia.] "in the third division is the family _sepiaria_, containing _octopus_, _lolìgo_, and _sepia_. this section contains animals without shells. _octopus vulgàris_ is common in the european seas. in hot climates it grows to a very large size. the animal has sufficient strength to draw a boat under water. "_lolìgo_ also is found in our seas; the thin, transparent rib, called the _dorsal blade_, you may probably find on the shore, the flesh that covered the blade being cleared entirely from it. the colour is either white or brown. it is called _sea-sleeve_. "the bone of the cuttle-fish, _sepia officinalis_, is so frequently thrown on shore by the waves, that few persons visiting the sea-coast can be ignorant of its form. you have a large collection there i see, lucy; and you are doubtless aware that this calcareous bone affords the _pounce_ of the stationers, when finely pulverized: it also forms one ingredient of tooth-powder. "the ink of this marine animal is contained in a bag: the use of the fluid is to colour the water around, in order to conceal itself from hostile attack. the flesh of some of these animals is used for food, and is frequently seen in the market at naples. in the british isles it is not put to any culinary purpose. the ink of _sepia_ can be prepared for a pigment, or paint. "the fifth and last order of the twelfth class is _heteropoda_, which contains only a few genera, one of which i shall notice. [sidenote: carinaria.] "_carinaria_, the glass-nautilus, is a rare and very precious genus, containing but three species. the first, _carinaria ritrea_, has been found in the southern ocean. there is a model of the shell in the british museum; that of paris possesses the shell itself. "_c. mediterranea_ is found in the neighbourhood of nice, and is frequent in the summer months. so thin and delicate is the shell that it is seldom found entire. "the shell of _carinaria_ is wholly external, and is attached to the upper part of the body, apparently to protect the organs of respiration. the body is transparent, dotted with elevated points; on the lower part is a beautiful reticulated fin, of a reddish colour; with the end of this fin it floats along, carrying its delicate shell. the habit of the animal, which swims upon its back, reverses the natural position of the shell, which is on the upper part of the body when at rest." "that is one of the most remarkable creatures you have yet mentioned," said charles; "i may chance to meet with a specimen when i travel." "probably," replied mr. elliot; "but our lessons are now concluded--_carinaria_ is the last genus." "how greatly we are obliged to you, father!" said lucy: "but i hope you will still give us a little advice and assistance: we shall often be unable to determine the genera of some shells, i am sure, especially among the bivalves." [sidenote: method of cleansing shells.] "most willingly: but tell me if you know the easiest method of cleaning shells when they become soiled, or when you purchase them in the natural state?" "that is a question i wished to ask." "a little warm water and soap will cleanse and render them bright. some collectors rub florence oil over their shells, which prevents them from becoming dry. a weak solution of gum-arabic is sometimes applied, in order to produce a polished and bright appearance. "nitric or muriatic acid, diluted, is used to take off the epidermis, or any extraneous matter; but it must be done carefully, and the shell plunged in water after the acid has been applied. but do not make a practice of polishing; shells are best in their natural state, generally speaking." "thank you, father!" said both the young people. "you are welcome to any instruction i can give you," he replied; "and now farewell for to-night." a list of species _that may be purchased at a moderate price._ examples of the genera that may be easily obtained from the british coast, or which are expensive, are omitted. _dentalium entalis._ _pectinaria belgica._[e] _balanus tintinnabulum._ _pentalasmis anatifera._ _corbula nucleus._ _psammobia virgata._ _lucina carnaria._ _cyprina islandica._ _cytherea chionè._ _venus tigerina._ _isocardia cor._ _arca noæ._ _pectunculus marmoratus._ _chama arcinella._ _tridacna crocea._ _pinna muricata._ _perna ephippium._ _meleagrina margaritacea._ _lima squamosa._ _spondylus gæderopus._ _chiton squamosus._ _emarginula fissura._ _fissurella græca._ _pileopsis hungarica._ _calyptræa equestris._ _bulla ampulla._ _helix melanotragus._ _pupa mummia._ _bulimus ovatus._ _achatina virginea._ _neritina corona._ _nerìta polìta._ _natìca alba._ _iànthina communis._ _sigaretus haliotoideus._ _pyramidèlla dolabrata._ _scalària commùnis._ _delphinula lacinìata._ _solarium perspectivum._ _trochus tuber._ _monodonta labio._ _turbo pica._ _phasianella bulimoìdes._ _cerithium vertagus._ _pyrula ficus._ _ranella crumèna._ _murex haustèllum._ _triton lotorium._ _pterocera lambis._ _strombus lineàtus._ _cassis arèola._ _ricinula horrida._ _purpura patula._ _monoceros imbricatum._ _concholepas peruvianus._ _harpa ventricosa._ _dolium maculàtum._ _eburna spiràta._ _terebra maculàta._ _columbella mercatòria._ _mitra episcopàlis._ _voluta musica._ _volraria monìlis._ _ovula oviformis._ _cypræa cribària._ _terebellum subulàtum._ _oliva utriculus._ _conus virgo._ _nautilus hians._ _spirula peronii._ [e] or _sabella_. index. page. acasta, acera, achatina, alata, ammonite, anatina, ancilla, ancylas, anodon, anomia, anostoma, annularia, aplysia, arca, argonauta, aspergillum, auricula, avicula, balanus, belemnite, bimusculosa, brachiopoda, buccinum, bulimus, bulla, calyptræa, cancellaria, capsa, caracolla, cardium, carinaria, cassis, cassidaria, cephalopoda, cerithium, chama, chamacea, chiton, cineras, cirrhipeda, clausilia, clavagella, cleodora, columbella, conchæ, conchifera, concholepas, conus, corbis, corbula, coronula, crassatella, crepidula, creusia, cyclas, cyclostoma, cymba, cypræa, cytherea, delphinula, dentalium, diceras, dolabella, dolium, donax, eburna, erycina, etheria, fasciolaria, fissurella, fusus, galeolaria, gasteropoda, gryphæa, haliotis, - harpa, helix, - heteropoda, hipponyx, ianthina, isocardia, lepas, lima, limax, lingula, litorina, loligo, lucina, lutraria, lymnæa, mactra, mactracea, magillus, melanopsis, meleagrina, melo, mitra, modiola, mollusca, monoceros, monodonta, murex, mya, myaria, mytilus, mytilacea, natica, navicella, nassa, nautilus, - nerita, neritina, nucula, nymphacea, octopus, oliva, onchidium, orthocerata, ostrea, otion, ostracea, ovula, paludina, pandora, panopæa, parmacella, parmophorus, patella, - pecten, pectunculus, perna, pentalasmis, phasianella, pileopsis, pinna, planorbis, placuna, plagiostoma, pleurotoma, plicatula, podopsis, pollicipes, potamophila, psammotæa, pterocera, pullastra, pupa, purpurifera, pyrgoma, pyrula, ranella, ricinula, rostellaria, rotella, rudista, sabella, scalaria, scapellum, serpula, sepia, siliquaria, sigaretus, solarium, solen, solenacea, spirorbis, spirula, spondylus, stomatia, stomatella, strombus, struthiolaria, succinea, tellina, - terebellum, teredo, terebra, testacellus, trachelipoda, tridacna, trigoniana, trivia, triton, trochus, tubicinella, turbinella, turbo, umbrella, unio, unimusculosa, valvata, venus, - venericardia, venerupis, vermetus, volvaria, voluta, vulsella, xylophaga, the end. joseph rickerby, printer, sherbourn lane. * * * * * transcriber notes all illustrations were moved so as to not split paragraphs. words with accented vowels were not standardized.