GIFT OF Miss Frances M. Molera EARTH SCIENCES LIBRARY OUR COMMON BRITISH FOSSILS BOOKS BY DR. TAYLOR. Crmvn 8vo, cloth extra, js. 6d. THE SAGACITY AND MORALITY OF PLANTS. A SKETCH OF THE LIFE AND CONDUCT OF THE VEGETABLE KINGDOM. With 100 Illustrations. " 'The Sagacity and Morality of Plants' is a delightful book, as readable as Grant Allen at his best. It contains all the cream of Kerner and Wallace and M tiller ; and, wonderful as is the story which it tells, it asserts nothing for which there is not the guarantee of some careful observer. We heartily recommend the book." Graphic. Crown 8vo, cloth extra, -js. 6d. OUR COMMON BRITISH FOSSILS, AND WHERE TO FIND THEM. A HANDBOOK FOR STUDENTS. V/ith 331 Illustrations. "Careful and systematic, the result of much observation and thought, while at the same time written in a popular and fascinating style. . . . The book deserves to be commended to the attention of all youthful students of geology." British Quarterly Review. Crown 8v0, cloth extra, $s. THE PLAYTIME NATURALIST. With 366 Illustrations. CONTENTS: An endeavour to enlist the young in a love of outdoor life and observation by chapters on Among the Birds Nimrods among the Lepidoptera Holiday Rambles and Adventures " They go a Fishing" Toads, Frogs, Newts, and Reptiles, etc., etc. New Edition. Fcp. 8v0, cloth, zs. 6d. NOTES ON COLLECTING AND PRE- SERVING NATURAL HISTORY OBJECTS. CONTENTS : Eggs, by T. Southwell Butterflies and Moths, by Dr. Knaggs Beetles, by E. C. Rye Mosses, by Dr. Braithwaite Fungi, by W. G. Smith Seaweeds, by Grattan, etc , etc. LONDON: G IBB INGS &> COMPANY. OUR COMMON BRITISH FOSSILS AND WHERE TO FIND THEM a f^antiboofc for gfctutente BY J. E. TAYLOR, PnD., F.G.S., ETC. AUTHOR OF "THE SAGACITY AND MORALITY OF PLANTS" ''THE PLAYTIME NATURALIST," ETC. WITH 331 ILLUSTRATIONS Honfcon CHATTO AND WINDUS, PICCADILLY 1885 [T/te right of translation is reserved} QE7/I T3 Mttft PREFACE. THE following pages are intended as a help to the young student of geology, who is usually bewildered by the abundance of invertebrate fossils when he first commences collecting them himself. There are books of a much higher and more extensive character, such as the treatises on Palaeontology by Owen and Nicholson, to which I am hopeful this present volume will prove introductory. I have not ^tempted to introduce the student to other than invertebrate fossil animals, not only because these are by far the most numerous, but also because such an attempt would have expanded the volume beyond due limits. I have recollected the nature of the difficulties which beginners in fossil-collecting feel, and have tried to meet them. My hope has been rather to whet the appetite than to satisfy it. IPSWICH, March 3, 1885. "3 CONTENTS. CHAPTER PAGE I. FOSSIL SPONGES, ETC. .. ... ... ... i II. FOSSIL CORALLINES ... ... ... ... 35 III. FOSSIL CORALS ... ... ... 55 IV. ENCRINITES ... ... ... ... ... 98 V. FOSSIL STAR-FISHES AND SEA-URCHINS ... ... 130 VI. FOSSIL WORMS (ANNELIDA) ... ... ... 158 VII. TRILOBITES AND OTHER FOSSIL CRUSTACEA ... 174 VIII. FOSSIL SEA-MATS (POLYZOA) ... ... ... 209 IX. FOSSIL LAMP-SHELLS (BRACHIOPODA) ... ... 222 X. FOSSIL MOLLUSCA (PAL/EOZOIC, OR PRIMARY) BIVALVES AND UNIVALVES ... ... 239 XI. FOSSIL MOLLUSCA (MESOZOIC, OR SECONDARY) ... 253 XII. FOSSIL MOLLUSCA (CAINOZOIC, OR TERTIARY) ... 271 XIII. FOSSIL CEPHALOPODS... ... ... 296 INDEX ... ... ... ... ... ... 325 LIST OF ILLUSTRATIONS. Acroculia haliotes, 124 Actinocrinus triacontadactylus, 101, 118 cuspidatus, 119 Agnostus pisiformis, 186 Ammonite, foliated chambers of, 306 Ammonites amaltheus, 313 bifrons, 311 communis, 3 1 1 Cooperi, 314 falcatus, 316 lautus, 316 Mantellii, 315 obtusus, 312 varicosus, 314 Amplexus coralloides, 63, 64, 65 Ananchytes ovata, 150 interior cast of, 150 Annelida, jaws of, 162 Anthracosia robusta, 249 Apiocrinites rotundus, 1 1 1 Apus productus, 195 Arenicolites sparsus, tracks of, 165 burrows of, 165 Asaphus caudatus, 177 Astarte Omallii, 287 Asterias tessellata, 132 Astrsea rotulosa, 67 favosa, 68 Astraea ananas, 69 Australian feather-star, 102 Astrocoenia gibbosa, 91 Atrypa reticularis, 225 Aviculo-pecten papyraceus, 250 B Baculites vertebralis, 323 Balanophyllia regia, 75 Beaked ammonite, 310 Belemnites hastata, 297 puzosianus, 297 (restored), 297 abbreviatus, 298 mucronata, 298 Bellerophon hiulcus, 248 Belinurus trilobitioides, 180 Bopyrus crangorum, 182 Botryllus on sea- weed, 214 Brachiopod, larval development of, 235 Buccinum undulatum, 282 Calymene Blumenbachii, 177 Cardiola interrupta, 244 Cardita imbricata, 274 Cardium Lillanum, 270 Caryopliyllia, 56, 74 LIST OF ILLUSTRATIONS. IX Ceratites nodosus, 306 Chain-coral, 61, 62 Chama squamosa, 269 Choanite, 22 Cidaris coronata, 146, 149 Clisiophyllum, 72, 73 Clymenia, 305 Comatula, 102 Crania, 226 Crioceras, 317 Crotalocrinus rugosus, 124 Ctenodonta contracta, 245 Cupressocrinus, 120 Cyathaxinias, 65 Cyprina islandica, 286 Cyprasa Europsea, 284 Cyrena antiqua, 272 Cyrtoceras Murchisoni, 300 D Dendrophyllia, 56 Dianchora striata, 269 Diastopora Oolitica, 217, 220 cells of, 218 ventricosa, 219, 220 Dibunophyllum, 86 Didymograptus, calycles of, 44 E Echinus esculenta, 145 granulosus, 152 Emarginala fissura, 279 reticulata, 284 Encrinus moniliformis, 101 Entomostracan, 201 Eucalyptocrinus, 117 Euomphalus pentangulatus, 250 Euryale costosa, 105, 107 palmifera, 106 Exogyra conica, 270 Eyes of trilohite, 180 Fascicularia aurantium, 220 Favosites cervicornis, 76 fibrosa, 77 Gothlandica, 57, 58 Feather-star, development of, 99 Fenestella membranacea, 216 nodulosa, 216 plebeia, 215 Fissurella Graeca, 280 Flustra, 213 cells of, 214 Foraminifera in Chalk, 32, 33 Galerites albogalerus, 151 Gervillea, 258 anceps, 269 Glauconome elegans, 216 flexicarinata, 215 Glyptocrinus, 119 Graptolite, twin, 43, 45 Gryphsea incurva, 257 H Hamites attenuatus, 319 Heliolites interstinctus, 79, 80 Heliopora cserulea, 59 Hippopodium ponderosum, 260 Histioderma Hibernicum, 166 tubular case of, 167 extremity of tube of, 168 Homalonotus, 189 Ichthyocrinus, head of, 117 Inoceramus sulcatus, 263 Cuvieri, 264 concentricus, 270 Isastrsea insignis, 92 oblonga, 93 LIST OF ILLUSTRATIONS. K Koninckphyllum, 87 Larva of king-crab, 178 trilobite, 178 Larval development of crab, 205 Leptsena transversalis, 224 Limulus, 179 Lingula, 224 ' anatina, 223 Lewisii, 224 Litharsea, 95 Lithostrotion junceum, 63 basaltiforme, 70 Phillipsii, 64, 71 Lituites articulatus, 300 Lonsdalia rugosa, 88 M Mactra, 281 Marsupiocrinites coelatus, 124 Marsupites Milled, 131 Membranipora membranacea, 210 polyps of, 211 cells of, 212 Micraster, 151 Millepora alcicornis, 60 Montilivaltia trochoides, 93 Murchisonia gracilis, 240 Mya arenaria, 286 N Nassa, 284 Natica monilifera, 284 Nereis, 169 Notopocorystes, 205 Nucula Cobboldise, 291 Obolus, 225 Oculina axillaris, 66 Ogygia Buchii, 190 Omphyma subturbinata, 75 Ophiocoma, 137 Ophiolepis Damesii, 142, 143 Ophiura granulata, 108 Orthis elegantula, 225 striatula, 227 resupinata, 230 Orthoceras, 299, 300 laterale, 299 Orthonota parallela, 240 Ostrea vescicularis, 270 Palseocoma Marstoni, 136, 139 Colvini, 139 Palasterina primEeva, 135 Paradoxides Tessini, 188 Davidis, 189 Pearly nautilus, 301, 302 Pecten asper, 268 Beaveri, 265 inequivalvis, 268 interstriatus, 267 orbicularis, 266 quadricostatus, 270 varius, 280 Pectunculus glycimeris, 283 Pentacrinus Caput-Medusce, 100 briareus, no Pentamerus Knightii, 225 Pentremites florealis, 132, 139 Phacops caudatus, 191 Phillipsia, 191 Pholas, in burrow, 284 Phragmacone, 298 Phragmoceras ventricosum, 321 Pileopsis ungarica, 283 LIST OF ILLUSTRATIONS. XI Plagiostoma giganteum, 259 Platycrinus trigintidactylus, 119 Pleurtomaria carinata, 249 Polypora, 216 tuberculata, 217 Posidonomya, 248 Poteriocrinus, head of, 122 ; stem of, 123 Prestwichia, 178 Productus giganteus, 224 horridus, 230 punctata, 229 scabriculus, 230 Protaster Miltoni, 134 Pterinea subfalcata, 244 Purpura lapillus, 282 Purpura tetragona, 290 R Radiolarian, 33 Retepora, 216 Rhodocrinus, 120 Rhynchonella pleurodon, 228, 229 pugnus, 226 Roots of encrinites, 120 Rostellaria Parkinsonii. 270 Sabella unispira, 163 Salenia, 152 Scaphites aqualis, 318 Scrolls Fabricii, 193 Sertularia abietina, 41, 42 fusca, 36 Sessile barnacle, 203 Shell of ammonite (section of), 37i 309 Shells of recent cuttle-fish, 304 Shrimp parasite, 182 Siphonia pyriformis, 20 Smilotrochus granulatus, 94 Spicules of recent sponges, 7 ; fossil, 8, 9 Spirifer, coils of, 227 cuspidatus, 228 speciosus, 227 striata, 228 trigonalis, 227 Spondylus spinosa, 269 Sponge imbedded in flint nodule, 2 1 Stalked barnacle, 203 Stenopora fibrosa, 77 Stromatopora concentrica, 15 Strophomena depressa, 226 rugosa, 226 Syringopora ramulosa, 59 Taxocrinus, 118 Tellina crassa, 283 Tentaculites annulatus, 164 Terebratula biplicata, 234 caput-serpentis, 237 deformis, 236 dorsata, 236, 237 hastata, 228 recent species of, 237 showing loop, 237 Teredo tubes, 273 Thecosmilia annularis, 93 Trigonia costata, 255 ; recent, 256 Trinucleus fimbriatus, 180 Lloydi, 191 Trochus, 281 Trophon contrarius, 281 Turritella, 275 granulata, 269 Turrilites, 303, 318 Bergerii, 319 xii LIST OF ILLUSTRATIONS. Turrilites costatus, 320 tuberculatus, 320 undulatus, 319 U Uraster rubens, 133 Ventriculites, 22, 23, 24 Vincularia, 217 Voluta athleta, 276 Lamberti, 291 W Woodocrinus macrodactylus, 121 Worm- tracks, 161 Zaphrentis, 65 OUR COMMON BRITISH FOSSILS. CHAPTER I. FOSSIL SPONGES, ETC. THERE are few sciences more dependent on others than Geology. Certainly there is none which sends the young student so eagerly to other sciences for assistance. The fossils he meets with in the rocks are far more abundant than he imagined before he began to study geology. Indeed, the young geologist, when his eyes are first opened, is astonished at the abundance of fossil remains within the immediate neighbourhood of his home, unless the latter happen to be on the granite or metamorphic rocks. He wonders how it is he never noticed them before. Fragments, or whole specimens of fossils, animal and vegetable, are con- stantly turning up before his eager and enthusiastic eyes, either in their parent rocks, or in the boulder clays which have been formed out of them. The very rocks of the hills and mountains seem to be 2 OUR COMMON BRITISH FOSSILS. almost wholly composed of them nay, the solid dry land of the globe appears to have been mainly put together by the agency or through the instrumentality of life ! No sooner has the young beginner appreciated the wealth of objects by which he is surrounded, or to which he may obtain easy access, than the first fit of collecting takes possession of him. His holidays are spent in fossiliferous localities ; and his leisure time in reading about them, or in arranging his cabinet At length he feels the need for more knowledge than he possesses about the many strange forms he comes across. He has at first an idea that they are altogether different from anything now existing, and perhaps a feeling of something like disappoint- ment comes over him when he learns they are con- structed on the same plan as living animals and plants ; and that in many instances the same generic and even specific forms are still in existence. This state of mind, however, soon gives way to thorough admiration, when he catches a glimpse of the life- plan of the globe. He sees that, beginning with the lowly and humble organisms, it has developed into the present Fauna and Flora ; that the stream of life, issuing like a rill from such obscure springs as are hardly discernible in the distant Laurentian period, has been gaining in volume and depth as it has passed onward, in unbroken continuity, through all the suc- ceeding ages, until it has opened out in the grand FOSSIL SPONGES, ETC. 3 ocean of existing life ! Every fossil he picks up is a letter in the great stone book ; and many such letters, properly put together, have spelled out some of the most wonderful generalizations of the human mind. For geology as a science is peculiar in this respect, that in proportion to the degree of intellec- tual labour bestowed upon it, the resulting knowledge is wider and broader than that afforded by any other science except, perhaps, astronomy. Not only does the new knowledge tell the student of other life- periods beside the present, not only does it extend the duration of the globe infinitely beyond the brief six thousand years uneducated people still imagine mark its existence, but it convinces the young student beyond a doubt, that if the present living animals and plants are evidences of the Creator's wisdom and power, the same may be said of the extinct faunas and floras of preceding epochs. Nay, when he learns properly to connect their nature and dis- tribution with the present, he sees that all are links in the great chain of vitality, of which existing animals and plants are only the continued living forms ! The next step in the process of geological reason- ing which fossils suggest, is no less interesting or instructive. From seeing how many of our rocks, especially limestones, are formed wholly by vital agencies, the student perceives that the physical geography of every past age is related to the present. 4 OUR COMMON BRITISH FOSSILS. The rocks forming the dry land are for the most part of marine origin were formed along the floors of ancient seas, when dry land doubtless occupied some parts at least of the areas of existing oceans ; although it should be remembered that modern science is actively developing the theory of the relative per- manency of ocean-beds and continental areas. No fact is more readily or surely known than that sea and land have frequently changed places. Upheavals and depressions of the earth's crust, producing mar- vellous physical results, and affecting the distribution of life-forms in every period of our planet's history, are of insignificant importance when we regard the bulk of our earth as a planet. It is the sum total of these depressions and upheavals, as well as of the atmospherical and marine wear-and-tear of the solid rocks, which has eventually given the surface of the globe its present physical geography. Of all these things the geological student has to take heed. He discovers that geology, after all, is but the complete record of the physical geography of the past ; and that, as Lyell and others have demon- strated, the physical changes everywhere going on at the present day do not differ in their nature, and probably not very greatly in their intensity, from those which took place in former geological periods. But, undoubtedly, the nature of geological study obliges the young beginner first to pick up an elemen- tary knowledge of natural history. How can he FOSSIL SPONGES, ETC 5 understand anything of the fossil plants, shells, bones, teeth, etc., he meets with in every geological forma- tion, unless he knows something about similar objects now in existence? Fossils only differ from their modern representatives in that they belong to extinct zoology and botany, instead of to the still existing divisions of these kingdoms of life. Thus the geological student is forced continually to widen his sphere of research, and he finds that every additional bit of knowledge of any other science helps him all the more to understand that which he has selected as his special hobby. Geology is essentially an open-air study. It leads one into the most beautiful of landscapes, to the most charming bits of scenery. The tame flatness of the plains reveals to the geologist comparatively little, unless coal or salt-mining has partly turned the earth's crust inside out ; or railway cuttings have laid open sections instructive both as regards the strata and the fossils they contain. Boulder clay pits or natural tarns will occasionally prove interesting. But to study the stony science in its fulness we must " gang to the hills ! " There, where the heather is purplest, and the atmosphere exhilarates like old wine, we are most likely to read off the " record of the rocks ! " Health- ful activity is required, and the memory is stored with remembrances of sunny days and clear skies never to be forgotten ! In the course of the following chapters I purpose 6 OUR COMMON BRITISH FOSSILS. doing my best to introduce the young student to the "happy hunting-grounds" of our various geological formations. I intend to limit myself to the common fossils, unless occasionally tempted to mention a few for the purpose of further whetting the appetite. And, whilst I describe the spots where the young geologist is most likely to " make a bag," I shall give a brief description of the natural history relationships of the numerous extinct organisms. For a long time it was the practice to regard the most doubtful fossil marine organisms, which had no particular shape or external structure by which they could be at once recognized, as " a kind of sponge." Thanks, however, to the labours of such men as Hinde, Sollas, and Carter, it is no longer possible to avail ourselves of such a fossil lumber-room, where our ignorance and mistakes can be screened. For, although there is some doubt and disputation as to the exact zoological rank of sponges whether they belong to the Protozoa or Ccelenterata there is little concerning their habits and structure. The extended use of the microscope in geology, and the practice of cutting transparent sections of any doubtful fossil, so as to enable the student to identify it by its organi- zation, at once enables him to detect " sponge structure," or rather the mineral part of that structure. For in fossils the sponge-flesh, or sarcode as it is called, has of course disappeared, and left no trace behind it. FOSSIL SPONGES, ETC. ^ As the reader may see by referring to Mr. Saville Kent's splendid work on " Infusoria," this sponge- flesh is frequently almost made up of collared in- Fig. i. Spicules of Recent Sponge (Chalina). fusorians, in company with myriads of still more simple organisms resembling Amoeba. A living sponge, therefore, may be regarded as a colony of lowly organized animals, just as a mass of living reef- coral is a colony of sea-anemone-like animals. Let us carry this illustration a little further. The coral-anemones differ from our well-known sea- anemones by the hard limy substances in their interiors, due to the calcification of the tissues. These remain behind after death, and when the flesh has OUR COMMON BRITISH FOSSILS. decomposed, such durable limy substances are popu- larly denominated "coral." Similarly with sponges. Fig. a. Fig. 3- Fig. 4. Figs. 2-4. Fossil Sponge Spicules, from Blackdown and Haldon, all drawn on the scale of 5*1 th to TS \j n th of an inch. (After H. J. Carter.) When alive the outer layer of " sponge-flesh " is usually permeated with myriads of exceedingly small FOSSIL SPONGES, ETC. 9 solid bodies, called fibres and spicules. The latter are of a variety of shapes, from the most simple to Fig. 8. Fig. 9. Figs. 5-9. Fossil Sponge Spicules, from Blackdown and Haldon, all drawn on the "i to r?'oD tn of an inch. (After H. J. Carter.) sea)', o the most complex, but they are interwoven so closely together that when the sponge is dead and its " flesh " io OUR COMMON BRITISH FOSSILS. has decomposed, there is left behind the skeleton, formed by the interlacing of the above-mentioned spicules. We may practically regard these " spicules " as having been crystallized within the soft, white-of-egg- like sponge-flesh. They are not always of the same chemical composition indeed they rarely are, even in the same species or individual. But there is generally an exclusive majority of spicules of the same chemical or mineral composition. The fibres are formed of a substance chemically resembling that which enters into the composition of horn, hair, wool, or feathers, and which is characteristically an animal production, called chitine. Our washing-sponge is the skeleton of the Chitinous group. Their skeletons, being usually fibrous, could hardly be expected to be found in the fossil state, unless they underwent a change. Two other classes of sponges are recognized by naturalists, and by some are named according to the substance of which the spicules of the skeleton are composed. Thus, in one group the spicules are formed of lime, and so the term calcareous is applied to them. Ten species of this sort of fossil sponge are found in the Ludlow rocks. In the other kind, the spicules are formed of silica or flint, and accordingly this group of sponges is termed siliceous. The last group possesses the most complex and beautifully shaped spicules, and the dead skeleton formed by them is one of the most lovely of FOSSIL SPONGES, ETC. 11 zoological objects, as everybody acquainted with the recent species Eiiplectella aspergillum ("Venus' flower-basket ") will readily allow. The accompany- ing wood-cuts show the appearances of recent and fossil sponge-spicules under the microscope. The siliceous sponges are again sub-divided into several groups, named respectively Monactinellidcs, Tetractinellida, Hexactinellida (that is, " one, four, and six-radiated spicules"), and Lithistidcs. We know nothing of fossil sponges except the mineralized spicules they have left behind, and these have been frequently much changed since the sponges were alive. Limy spicules are often dissolved away, and perhaps left no trace behind them, unless the hol- lows they had left have been filled with flint. But there are numerous cases where even flint spicules have been dissolved, and where lime has replaced silica. Until a few years ago, it would have been much questioned whether the siliceous spicules of sponges could be replaced by any other mineral matter ; but there is now little doubt that organic silica can be removed, although geologists can only record the observed fact without explaining it. Some siliceous spicules have been replaced by iron pyrites, in the Lower Cambrian rocks of North Wales. Nevertheless, fossil sponges possessing a siliceous or flinty skeleton, are likely to be much more numer- ously preserved than those sponges whose skeletons were composed of a less endurable mineral. Hence 12 OUR COMMON BRITISH FOSSILS. the former appear to be more numerous and wide- spread. Dr. Hinde refers to instances where the spicules of Tetractinellid, or four-rayed sponges, are numerous enough to form thin strata. The Hexactinellid sponges are distinguished by having six-rayed spicules, so arranged that the rays are usually at right angles to each other. These spicules are sometimes united, sometimes free, and they frequently form a trelliswork after the appearance of " Venus' flower-basket." These are all inhabitants of the deepest parts of the sea, and as our white chalk is one of the geological formations deposited perhaps in deeper water than any other, the number of species of fossil hexactinellid sponges found fossilized in its strata is very great. The Ventriculidce (formerly thought to be zoophytes allied to the Alcyonia, or " dead men's fingers ") are perhaps the most numerous of all the chalk sponges, and even the external shapes of many of them approach very near to that of " Venus' flower-basket," and still more to the recent sponge called Holtenia. The Lithistidce are sponges whose spicules are also composed of silica, but they are arranged in fotirs, and the rays are not arranged at right angles. The extremities of the spicules are usually so divided or notched that those of each other can interlock. This interlocking builds up a loose but continuous framework. One of the commonest of the fossil sponges in the Lower Chalk is Siphonia, which FOSSIL SPONGES, ETC. 13 may be regarded as a characteristic lithistid sponge. Fossil sponges are always commonest in limy and arenaceous rocks. As regards the habits of recent sponges, it is as well to be acquainted with them, for they throw light upon the conditions of ancient sea-beds, inasmuch as we find that modern sponges are characterized by the same habits as the oldest kinds. In this way a knowledge of recent and fossil forms is reciprocal in its illustrative effect Thus the genus Cliona a remarkable sponge which has the habit of boring into the denser structure of bivalve shells, as may be seen in a thick-shelled, deep-sea oyster on the nearest fish- stall has indulged in this habit ever since the Silurian period. Shells of fossil Pterinea, in the Malvern beds, are frequently found perforated by ancient burrowing sponges ; and in the chalk near Norwich we find the solid cones of Belemnites (internal bones of ancient cuttle-fishes) riddled through and through by boring sponges, which have thus left a very delicate but graceful pattern of the walls of the burrows. Again, in our British seas particularly, we have a large number of existing sponges encrusting or growing on other natural objects ; and we find fossil sponges such as Sparsispongia which adopted this habit as far back as the Silurian times. It is probable that in the earlier seas of the globe the divisions of the lower marine animals were not so distinctly marked off from each other as they are 14 OUR COMMON BRITISH FOSSILS. now. This accounts for the difficulty some of our best naturalists find in assigning certain fossils to their true classification. Thus, Mr. Carter thinks that Parkeria (a not uncommon fossil in the Upper Green- sand of Cambridgeshire, and which was originally described by Dr. Carpenter as a gigantic foraminifer an inch in diameter, whose walls are composed of cemented grains of sand instead of "shell") is in reality a hydrozoon allied to the pretty Hydractina found coating the outsides of many living whelk shells. The same naturalist believes that Stromatopora is of similar character. The latter is a very abundant fossil in the Devonian limestone. In the quarries at Newton Abbot one can hardly pick up a piece of stone which does not contain some species of Stroma- topora. It is found in the Silurian, Devonian, and even Carboniferous limestones. The beautiful flesh- tinted marbles obtained from the Devonian limestones near Torquay, when polished, show excellent sections of Stromatopora. How this fossil has been bandied about from scientific pillar to scientific post ! For a long time it was regarded as a species of coral. Then it was supposed to be a calcareous sponge. Next it was imagined it might be somehow intermediate between the hexactinellid sponges and such hydrozoan corals as the recent and abundant Millepora. Professor Nicholson threw out the hint that this fossil might be related both to sponges and foraminiferae ; whilst Pro- fessor Sollas holds to its being a hexactinellid sponge. FOSSIL SPONGES, ETC. Fig. io. Sections of Stromatopora concentrica (Upper Silurian and Devonian formation) : a, surface of fossil : b, vertical section ; c, portion of Stromatopora concentrica (magnified). 16 OUR COMMON BRITISH FOSSILS. The discovery that many sponges which originally pos- sessed flinty or siliceous spicules have had them con- verted into lime a most unexpected metamorphosis, but one which cannot be gainsaid has greatly per- plexed naturalists as to which were formerly calcareous and which siliceous sponges. Thus Zittel, the great authority on fossil sponges, regards those which are so abundant in the Coral Rag beds at Farringdon, as calcareous ; whereas Carter thinks they were ori- ginally siliceous sponges whose spicules have been chemically changed. This only shows how involved are the problems dealing with the most simple and rudimentary of marine animals. But the fact remains, that sponge- life has not materially altered from the very earliest period of our planet's history until now. There is a much greater variety of species in recent seas than perhaps was ever the case before, although it is doubtful whether sponges are as abundant in any of our great seas or oceans as when the European Chalk was deposited. Fossil sponge-hunting becomes most interesting when we come to the Cretaceous or chalk formation. True, we find fossil sponges in all marine calcareous and arenaceous formations, from the Silurian upwards. Even fresh-water sponges, closely allied to that now abundant in rivers and streams {Spongilla fluvia- tilis), are known to have been in existence during the Purbeck limestone stage of the Secondary epoch. FOSSIL SPONGES, ETC. 17 Apart from fossilizing for Stromatopora certain to be found in most quarries where the Upper Silurian or Devonian limestone is worked until we come to the Carboniferous limestone we should hardly reckon our sponge "finds." Calcispongia, Protospongia, Ischadites, Astylospongia> and Amphispongia are not uncommon Silurian genera found near the Malverns, at Ludlow, and in the Longmynds. Fifteen species of sponges are described from the Carboniferous limestone, Palceacis being the commonest. The young hunter for this kind of geological spoil should first make himself acquainted with the various appearances of sponge structure under the microscope with the fibrous as well as the spicular details. Then he will be prepared, when out on his rambles, to examine any suggestive materials. One of the most profitable geological rambles, in this respect, I ever experienced was on the Carboniferous limestone of Black Head in County Clare a spot not likely to be soon for- gotten by those who love natural scenery. The limestone is traversed by numerous joint-fissures, in which grow the loveliest of ferns, the maidenhair (Adiantum capillus-veneris] being especially luxuriant and abundant. Before us break the rollers of the wide Atlantic ; behind us the hills rise in gentle slopes for they are formed of black, fossiliferous Yoredale shales. The walls by the roadside, which take the place of hawthorn hedges, are crowded with fossils. Some C 1 8 OUR COMMON BRITISH FOSSILS. of the limestone appears friable and " rotten." This is just the material to look for microzoa, for Radio- larians, sponge-spicules, etc. Those of a fossil " glass- rope " sponge (Hyalonema) are met with in abundance. Mr. James Thomson, F.G.S., discovered a bed of " rotten limestone " at Cunningham Baidland, Dairy, Ayrshire, and the spot is now well known to all Glasgow geologists. Sponge spicules, notably those of Hyalonema, are abundant, and they are found converted from their original siliceous to a calcareous composition. Several other places where microzoa occur have been made known in Scotland ; and Mr. John Young, F.G.S., has carefully examined their materials and published details of his discoveries in the "Transactions of the Glasgow Geological Society." Whenever the rock appears "rotten," or the thin beds of limestone shale which are frequently " sand- wiched" between the limestones seem more than usually crumbly, the student should box some of the material, and carefully note where he obtained it. At home, with the aid of the microscope, he can occupy his winter evenings in its examination, and perhaps he may thus add to our scanty knowledge of Palaeozoic sponges. Until we come to the Cretaceous rocks, we know almost less of the structure of the Secondary sponges than of those just mentioned. There must be remains of them somewhere, and by looking out keenly for rocks having a peculiar structure, which the student FOSSIL SPONGES, ETC. 19 will soon recognize, he may fill up some of these numerous blanks in our information. The Portland stone is in places crowded with tri-radiate sponge- spicules ; the Kentish Rag is frequently so full of the same objects that it hurts the hands of the men who work in it. In the rocks of the Great Oolite Mr. Etheridge says sponges abound, nine species being known. At Haldon Hill, near Exeter, we have an outlier of Greensand, where a thin layer contains lithistid sponge-spicules very abundantly. Mr. Carter thinks this bed of sponge-spicules may have been formed along the sea-floor, after the manner in which a similar layer of sponge detritus is now forming at sea, about one hundred miles to the north of the Butt of Lewis. The powder to be found in most hollow flints is the best kind of material microscopically to examine for spicules. Dr. Hinde, who has published an in- teresting essay on " Fossil Sponge-Spicules from the Upper Chalk," therein shows how much can be seen and discovered by carefully examining only a few ounces of this material. Those who have geologized on the flints found in chalk strata are well aware that the chalky material filling the hollow flints is of a different appearance, both to the eye and the touch, than the chalk itself. Dr. Hinde calls this powder " flint-meal " a term which conveys a capital idea of what it is like. Wherever there are chalk OUR COMMON BRITISH FOSSILS. flints the student may be sure to find abundance of fossil sponges. The hollow ones should have their interior contents carefully boxed for subsequent examina- tion. I have frequently carried as much "flint-meal" away in a small pill-box as afforded a week's work with the microscope. Many flints are called " rot- ten " by the quarrymen because they are permeated by irregular canals, branching off from each other like the twigs of a tree. Sometimes these canals are filled with "flint-meal," which should be carefully collected. The sur- faces of the walls of these branch- ing canals or passages are always rough. It does not require much acumen to see that these are due to fossil-branching sponges, resembling in shape the Chalinas and Halichondrias of our British seas. All geologists are now agreed that the flints of the chalk formation somehow as- sumed their present shapes, appearance, and distri- bution through the agency of crops of sponges which flourished on the ancient Cretaceous sea-bed. Con- Fig, ii. Common Fossil Sponge from Greensand (Siphonia pyriformis). FOSSIL SPONGES, ETC. 21 sequently the study of the chalk-sponges is intimately connected with the origin of chalk-flints, and perhaps also with that of " chert." No one can work at these flints long without seeing that the external shapes of the flint-nodules are very often determined by the shapes of the fossil- Fig. 12. Common Branching Sponge, imbedded in flint-nodule. sponges they enclose. In many instances the surfaces of the flints are marked by indications of the enclosed fossils cropping out. This is particularly the case with the Ventriculites and the Spongites (as Mantell called them). The latter are the branching sponges which cause the flints to be "rotten." In the pits 22 OUR COMMON BRITISH FOSSILS. near Lewes, Spongites ramosus may be gathered, twelve to fifteen inches long. In many places, as in Fig. 13. Horizontal section of Flint, containing Choanite, or lower part of Ventriculite, showing sponge foldings. Fig. 14. Longitudinal section of Ventriculite imbedded in flint. Fig. 16. Ventriculite in Flint, showing external markings in upper part- Fig. 15. Longitudinal section of Ventriculite in flint-nodule, showing roots. any chalk pit on Salisbury Plain, the collector finds that nearly every flint is " rotten ; " the branching FOSSIL SPONGES, ETC. 23 canals within represent the entombment of sponges which have decayed, all but their spicules, now form- ing the " flint-meal." The most " rotten," or sponge- bearing chalk-flints I ever worked upon are those of Fig. 17. Ventriculite. Flamborough Head, in Yorkshire, and Trimingham, in Norfolk. In both cases the fossil sponges are of the kind called Lithistid, the hexactinellid sponges being rare. The external shapes of lithistid sponges vary to an enormous extent, even in the same genus. 24 OUR COMMON BRITISH FOSSILS. Generally, however, they are of a stony character and solid everywhere, except in the pure white chalk. The Ventriculite family of sponges are hexactinellid, and their shapes and structures are often very beau- Fig. 18. Ventriculite. tiful, a slight magnifying power showing a similar latticed appearance to that we admire so much in the modern "Venus' flower-basket" (Euplectella). In the white chalk of Sussex, Wiltshire, and Norfolk, Ventriculites occur in great numbers, Ventriculites FOSSIL SPONGES, ETC. 25 radiatus being perhaps the commonest. This species frequently forms the nucleus of flints, the flinty matter just covering it, and thus assuming its shape. The general shape of these Ventriculites is that of an old-fashioned wine-glass. The stems and bases of such an imaginary wine-glass (when thoroughly silici- fied) are the well-known Choanites of the " Brighton pebbles." A nearly allied and very elegantly marked genus of sponges is Coscinipora. If we try to imagine a Ventriculite flattened down into the similitude of a finger-basin rather than a wine-glass, we shall form a good idea of a much larger, nearly related, and not uncommon hexactinellid sponge, called Cepha- lites. Other pretty fossil sponges belonging to this division are Camerospongia^ Ccsolptychium y and Callo- dictyon. The lithistid sponges are very abundant in some parts of the Lower Cretaceous rocks. The principal genera are Sipkonia, Polypothecia, Scypkia, etc. The former genus is perhaps the commonest, and there are several species classified as belonging to it Most young geologists are acquainted with the pear-shaped, stony heads of a species called Siphonia pyriformis. Very frequently they break off the stalks, and we find head, stalk, and roots separately. In the " fire- stone" of St. Catherine's Hill, above the road from Niton, Isle of Wight, we may obtain any quantity of Siphonia Websteri ; near Ventnor, 6*. pyriforme is abundant. In the Upper Greensand at Farnham, in 26 OUR COMMON BRITISH FOSSILS. Surrey, these sponges are very abundant ; but they have undergone a chemical metamorphosis, and have been converted into phosphate of lime to more than fifty per cent. On this account they are worked, and ground up into artificial manure, or super-phosphates. At Farringdon, in Berkshire, and at Warminster, we have the geologically famous "sponge-gravels," an ancient sea-bed, with whole and broken shells, frag- ments of Echinoderms, etc., through which is dispersed an abundance of fossil sponges. That called Manon is common, and the quarrymen term it " petrified salt- cellar." I have often noticed that when fossils obtain popular names, it is a sign of their abundance. In the Upper Greensand at Folkestone, the fossil sponge termed Scyphia meandrina is especially abundant Polypothecia is one of the commonest of the fossil sponges met with in the Greensand at Warminster. It is a branched sponge, allied to those known as Spongites, and it puts one in mind of our common British Chalina, so abundant along our coasts. When found it is usually of a stony texture, but sections of it show it to belong to the lithistids. One of the most gigantic of probable sponges is that called Paramoudra, abundant in the chalk near Norwich. There is now little doubt this singular object was a sponge. It is frequently found in the chalk, always extending upwards in a perpendicular fashion to the height of five or six feet, and having a basal diameter of two feet. Its appearance is like FOSSIL SPONGES, ETC. 27 that of a series of cups one inside another, the largest ones at the bottom, and the smallest at the top. The topmost segment is usually crowned with an extin- guisher-like cap, at the side of which we observe a perforation, which is connected with the traces of a pipe running down the centre of the chalky core occupying the segments of this peculiar fossil. Each segment is therefore hollow, or rather occupied with a dense core of chalk. The country people use the segments for flower-pots in their gardens, after they have removed the chalky core. Fossil sponges are also obtained by hammering the most likely and " rotten " of the flint pebbles forming the gravel of the eastern and southern counties of England. It is only when we are familiar with the extent and thickness of these sheets of gravel that we can form an idea of the extent to which the chalk has been denuded ; for every one of these flint pebbles is a broken-up, rounded, or liberated portion of a flint nodule, which was origin- ally formed by chemical segregation in the ooze of the Cretaceous sea-bed. The comparatively recent application of the microscope to rock structures has supplied us with abundant materials for generalization. This instru- ment enables us to detect plentiful traces of fossils where, to the naked eye, the rocks appear quite destitute of them. This is particularly the case in limestone beds. Among the most numerous of the 28 OUR COMMON BRITISH FOSSILS. organic remains thus identified are those small and beautiful objects, the foraminifera. Microscopically small though they are, it is questionable whether the bulk of our limestones is not more due to them than even to ancient coral-reefs ! The fossil foraminifera are usually represented by small limy shells, or casts of them. The creatures to which these belonged were of very low organiza- tion, rising scarcely above the zoological rank of the little amcebas of our ponds and ditches. These minute shells are abundantly perforated, in one division, for the passage of spider's-web-like threads of protoplasm which proceed from the animal's body ; in another division the shells are imperforate. Some- times the soft bodies were protected by walls of minute sand-grains. The oldest so-called, but much debated organism yet recognized, is Eozoon Canadense, and this is regarded as a foraminifer. We pass over the Eozoon, however, because its organic nature is still held to be doubtful. "Eozoonal structure," as it is now termed, is not confined to the oldest Lauren- tian rocks. Professor King has discovered it in the Ophite, or metamorphosed Liassic rocks of the island of Lewis. It is also abundant in the green crystal- line marbles, of Lower Silurian age, in Connemara, in Ireland ; and something approaching it has been found in Sutherlandshire. Now, the distribution of lowly organized forms can never be safely accepted as indicating the age of a rock. Naturalists are well FOSSIL SPONGES, ETC. * 29 aware that the most lowly organized animals and plants are those which have had the v/idest dis- tribution, both in time and space. It is the most highly organized species of animals and plants which best mark the geological ages of formations. So that the fact of finding " Eozoonal structure " in limestones other than the Laurentian, is of itself no evidence against the animal nature of the Eozoon. In many places such limestones as the Carboni- ferous do not show visible traces of fossils. I have frequently found, in such cases, that a prepared section of such a rock shows it to be unusually rich in foraminifera. In some parts of the world limestones have been almost wholly composed of the shells of these lowly organized animalcules, such as the Fusu- lina Carboniferous limestones of Russia and North America, the Nummulite limestones, of which the Egyptian Pyramids are built, etc. In England, our white chalk is very largely composed of foraminiferal remains, chiefly Globigerina, represented by species which are still living in the Atlantic and Pacific, where the recent dead shells are accumulating and decom- posing and forming a similar bed of chalky ooze on the ocean-floors. Some species of foraminifera, such as the recent Webbina rugosa, have been found in the fossil state in the Lias rocks, so that they have been in continuous existence ever since. One species, Saccamina Carteri, forms almost entire beds of limestone in the north of England and the south of 30 OUR COMMON BRITISH FOSSILS. Scotland. This is a tolerably large kind, being nearly one-eighth of an inch in length. The Carboniferous limestone in many places is very rich in foraminifera. According to Mr. Etheridge, these are represented by fourteen genera and forty- eight species. The most important genera are Saccamina, Stacheia^ Nodosinella, Dentalina, Textu- taria, Fusulina, Calculina, etc. The White Chalk, however, is the great storehouse of well-preserved and easily extracted fossil foramini- fera. These minute shells are especially abundant in some kinds of "flint-meal," obtainable from hollow flints, as already described. The chief genera of Cretaceous foraminifera are Globigerina, Dentalina, Marginulina, Frondicularia, Textularia, Gaudryina, Verneuilina, Bulimina, Truncatulina, Rosalina, Rota- Una, Cristellaria, Lituola, etc. These minute but exceedingly beautiful fossils may be extracted from any piece of white chalk as follows : First, get together an apparatus consisting of two ordinary medicine bottles, and about eighteen inches of small indiarubber tubing, such as can be purchased at any chemist's. Procure a piece of soft chalk, the softer the better, and that which has been partially broken up by the action of the weather better still. Scrape this with a knife to a fine powder, and put it in one of the bottles, which should not be more than about one-tenth full ; then fill up the bottle three-parts full of water and shake vigorously and FOSSIL SPONGES, ETC. 31 repeatedly ; allow this to stand for some time, and then draw off the milky fluid with the siphon. Do this again and again, until when shaken up the bottle appears as if it were no longer full of a milky fluid, but, when placed close to the eye against a bright light, of small separate grains diffused in the water. These are the treasures we are in search of, but they have next to be separated from the larger fragments of chalk which have not been disintegrated by the scraping and shaking. To do this shake up the bottle, and with the siphon im- mediately draw over water and foraminifera into the second bottle ; thus a certain portion of shells to- gether with nearly all the water is drawn over. Allow these to settle ; then draw off the clear water and repeat the process until all or nearly all the shells are in the second bottle, leaving the lumps, etc., in the first ; then filter with blotting-paper, and dry in an oven, when they will be ready for mounting. I reckon about one pill-box full of foraminifera to a washing, and store the preparation dry. Boil them in a test- tube with turpentine, and mount in balsam. The more solid limestones of the Silurian or Car- boniferous age, in which we suspect the presence of foraminifera, must of course be treated in another way. The student may frequently detect the pre- sence of foraminifera by means of a good Coddington lens. Thin chips of the limestone should be carried away, ground on one side, mounted on glass, and then 32 OUR COMMON BRITISH FOSSILS. ground on the other side until they are thin and transparent enough to be properly mounted for microscopic examination. In this way some exquisite geological slides may be prepared. Fig. 19. Globigerina cretacea (common). Fig. 20. Rotalina Voltziana. Common Foraminifera in White Chalk. Some of the limestones yield even still more beautiful Radiolarians, although there is little doubt that, in some way, the bands of chert which run through our Carbon- Fig.23. Recent iferous and other limestones, have been species of Dentalina. formed partly through the agency of these siliceous-shelled animalcules, for we usually find them absent where chert-bands occur, and present where FOSSIL SPOA T GES. ETC. 33 they do not ; as if, in the former case, their silicated shells had been dissolved, and the silica drained off to Fig. 25. Transverse sections of Foraminifera ir limestone (magnified). Fig. 24. Appearance of fossil Foraminifer in Carboniferous limestones (magnified). Fig. 26. Fragment of fossil Foraminifer (magnified). Fig. 27. -Radiolarian (recent). 34 OUR COMMON BRITISH FOSSILS. form the chert. This is frequently the case in the chalk. Radiolarians and other minute siliceous organisms are present in great abundance, diffused through the chalk where there are no flint-bands or nodules ; whereas the chalk is always freest from them where such nodules regularly occur. In this manner the student perceives that the presence or absence of some of the most minute of animal remains may determine the petrological character of the great rock masses which build up the continents of the globe. ( 35 ) CHAPTER II. FOSSIL CORALLINES. REGARDING another group of fossils (named after Professor Oldham), geologists have long been in doubt as to whether they were animal or vegetable. Oldhamia is called a zoophyte, an unfortunate de- signation, which often conveys to many people the idea that such objects are partly animal and partly vegetable. The name was originally intended to ex- press only their external resemblances to plants ; but it is constantly twisted to signify a hybrid combination of animal and vegetable characters. The Oldhamia the fossil about which I am now speaking has been alternately regarded as a seaweed and a zoophyte. Mr. Salter thought that possibly it was a calcareous or limy seaweed, like the common Corallina officinalis, which may be found abundantly in every rock-pool at low water. The latter is undoubtedly a seaweed ; but its limy structure and jointed stem caused it to be regarded by the earlier naturalists as a Coralline ; whence its name. Professor Edward Forbes believed 36 OUR COMMON BRITISH FOSSILS. that the Oldhamia showed, at the articulations of the stems, the positions of the minute cells of zoophytes. The most likely idea is that this very pretty and interesting fossil the oldest British organic form with which we are certainly acquainted was related to the little "sea-firs" so abundant nowadays along our coasts. Indeed, not a few of these Sertularians (as Fig. 28. a, Sertularia fusca / b, Pinna, with calycles (magnified); c, Plumularia. frutescens ; d, Pinna, with calycles, nematophores, and capsule (magnified). they are called) resemble in external shape the hamia. The dry portion that remains when the zoophytes are dead, is of a horny nature, and formed of chitine. This is one of the most indestructible of animal substances, and is likely to be preserved when others would be decomposed. If the Oldhamia had been calcareous, the limy matter would have been dissolved away, and few or no traces of them would FOSSIL CORALLINES. 37 have been left. The most probable zoological position of the Oldhamia is among the Hydrozoa, of which the " sea-firs " (commonly mistaken for seaweeds) which may be seen abundantly clustering on the backs of oyster-shells in any fishmonger's shop, are the most familiar examples. The Graptolites, which are so numerous in the Lower Silurian rocks, as we shall presently see, probably belonged to another division of the same class of lowly organized marine animals. Two species of Oldhamia are known to geologists, each distinctly marked from the other. Both are found in the same locality viz. the Cambrian rocks of Bray Head, about four or five miles from Dublin. The place is easily reached, and will not soon be for- gotten by the geological student. The rocks where the Oldhamia occur are beyond the village, and form the southern horn of the bay. They are very smooth and fissile, and almost of a claret-colour. The fossils, which sometimes occur along with the borings and traces of marine worms, lie in zones, for certain strata yield them more abundantly than others. In the neighbourhood of the bathing-place, where the sea- water appears unusually pure and green in com- parison with the claret hue of the rocks, the Oldhamia may be gathered in abundance. The species antiqua also occurs in yellowish shales of the same geological age, in Carrick mountain, county Wexford. Hitherto, both species have been limited to the Cambrian rocks of Ireland, where, however, they do not seem to have 38 OUR COMMON BRITISH FOSSILS. a very wide distribution. The other species (Old- hamia radiatd) differs from the former in having the setae circularly radiated instead of being fan-shaped. It is also found at Bray Point, county Wicklow, and the student will there readily meet with it in the strata known to all in the neighbourhood as the " Periwinkle Rocks." Apart from the pleasure of collecting these neat little fossils, the visit to Bray Head will amply repay the tourist. It is one of the pleasantest seaside watering-places in Ireland. The zoology of the rock- pools about the Head is very rich, and the visitor interested in this study and geology might profitably spend a few days there. Nor would his pleasure be marred by the demonstrative gaiety of the humble wedding-parties which make Bray their place of festivity. The village is easily reached by rail from Dublin ; and is especially interesting to the geologist as the locality where the " oldest British fossil " is found. Of the many thousands of species of fossils found in the rocks of Great Britain, from the most ancient to the most recent, perhaps no group so markedly distinguishes a formation as that popularly termed Graptolites. They are peculiar to the Cam- brian and Silurian systems, and have not hitherto been found elsewhere ; being most abundant, however, in the Lower Silurian rocks. Wherever the Lower Silurian rocks have been explored, if they have been FOSSIL CORALLINES. 39 unmetamorphosed so that the fossil remains have not been obliterated, Graptolites have been generally found in large numbers. Not unfrequently they are so abundant as to form a kind of carbonaceous matter in the rocks where they are enclosed. Their geographical distribution is exceedingly great, and, as they mark definite geological horizons, no other group of fossils is more valuable in enabling us to arrive at the age of the rock-zones where they are found. To the palaeontologist and zoologist the Grapto- lites are unusually interesting, on account of their resemblance to, and yet marked deviation in structure from, a well-known and widely distributed living group of marine objects. Moreover, even among the Graptolites themselves there is a striking dif- ferentiation ; a " differencing," however, which has a foundation of resemblance to start from. Perhaps more papers have been written about the Graptolites than any other fossils, not even excepting Trilobites and Ammonites ; and not a few workers have come to wordy blows about them ! This difference of opinion has arisen from the endeavour to stretch or expand palaeontological facts so as to fit them into the natural history scheme formed for the purpose of classifying and arranging recent animals. Now that the theory of evolution has gained ground among our best naturalists, let us hope its Christian effect will be to remove all accessory causes of " bad blood," by point- ing out that, however perfect our existing scheme of 40 OUR COMMON BRITISH FOSSILS. classification may be for living forms, it is unphilo- sophical to expect it will fit with equal accuracy those of long bygone periods, when animals frequently possessed characters which have since been divided among different genera. Indeed, it would appear as if the Graptolites were, in some respects, a class of those "missing links" which connected two great divisions of animal life now distinct from each other. The young geological student finds himself in no small degree perplexed when he first endeavours to find out the zoological relations of the Graptolites. Page refers some of them to the true "sea-pens" (Pennatula and Virgularid), with which, however, they have nothing in common, except the mere external resemblance the double Graptolites bear to them. The Pennatulidce are nearly related to those familiar objects of our coasts, popularly called "dead men's fingers" (Alcyonium digitatum). Other writers place the Graptolites among the Polyzoa, or " sea-mats." They are now, however, regarded by Lapworth, Hopkinson, and others as undoubtedly Hydrozoa, and very nearly related to the " sea-firs " {Sertularidce}. They differ from the Sertularians in some marked particulars, especially in the possession of a solid axis whence their general name of " Rod- bearers " {Rhabdophord) ; among others, in the posses- sion of characters which caused Professor Allman, the great authority on the Hydrozoa, to regard them as intermediate between the Hydrozoa and Rhizopoda FOSSIL CORALLINES. 41 Mr. Hopkinson does not think there is any absolute structural difference between Graptolites and Sertu- larians, and his recent discovery of gonothecce (or egg- bearing capsules) in Graptolites, similar to those seen in Sertularians, has confirmed his opinion. In the " sea-firs " (Figs. 28 and 29), we have a horny stem, hollow throughout, giving off branches, like a miniature tree. These branches are also hollow, and Fig. 29. Common Sea-fir (Sertiilartct abietind). communicate with small cups called Hydrothecce. In each of the latter a distinct zoophyte lives, capable of slowly putting forth its fringe of tentacles beyond the rim, and of withdrawing them again. Each individual is connected, by means of the simple fleshy tissue (caznosarc) which fills the hollow stems and branches, with every other on the same colony or polypary. At the base of each of the small cups is a partition, 42 OUR COMMON BRITISH FOSSILS. just separating the individual zoophytes. The horny matter, it must be remembered, is secreted by the soft, simple flesh (ccenosarc). At certain times there will be borne on the branches, horny capsules, much larger than usual. These are the gonotheccz, for the special purpose of reproduction. The young ova issue hence as little free-swimming animals ; some of them to assume, during their wandering life and before they settle down to bud and produce a " sea-fir " colony Fig. 30. Magnified calycles (a) and capsule () of common sea- fir (Sertularia abietina). the appearance, and partly also the structure, of jelly-fish. Now in many respects the Graptolites resembled recent Sertularians. First, they were composed of a similar horny or chitinous external substance, which, indeed, is all that is left of them in the fossil state, just as the entangled masses of the " sea-firs " so often picked up along the coast and mistaken for seaweeds, FOSSIL CORALLINES. 43 are all that is left of the living colony of which they formed the more solid and endurable parts. The Graptolites also were like the Sertularians in being compound animals, or rather, a colony of simple, hydra-like creatures ; whence the name of Hydrozoa. In the Graptolites, however, the horny cups are crowded closely together, so that they are all in con- Fig. 31. Twin Graptolite (Didymograptus Murchisoni). tact (Fig. 32), whereas in the modern Sertularians they are distinct. In one genus of Graptolites, how- ever, the cups are separate, and from the resemblance they have to the teeth of a rake (Latin raster, a rake), these forms go by the name of Rastrites. They are usually coiled up like toothed watch-springs, 44 OUR COMMON BRITISH FOSSILS. and are among the prettiest of all the Graptolites. Their resemblance to the brass-toothed wheels of watches is often still further borne out by the Rastrites having had their substance converted into iron pyrites, the gilt out- lines standing forth in very bright relief from the surfaces of the black shales in which they are imbedded. Fig. 32. Calycles * QiD Mu^chiso a tus These toothed projections, seen on the (magnified). outer margms Q f ^^ s i ng l e anc j double Graptolites alike, are regarded by most naturalists as identical with the cups of recent " sea-firs," or Sertu- larians, and therefore as having contained zoophytes when the Graptolites were alive. Professor Allman, however, doubts whether the Graptolites had cups at all, and thinks that these projections were like those seen on the embryonic stem of the Lobster's horn Coralline (A n- tenmilaria), which bear nematopJiores. Dr. Nicholson figures the egg-bearing capsules of Graptolites in his "Manual of Palaeontology," and his " Monograph of the Graptolitida? where he sets forth their resemblance to the gonothecce of the Sertularians. He states he found them both attached to the branches of the Graptolites, and separate, and has no doubt as to their being the egg-bearing cases of the ancient Graptolites. Neither Allman nor Carruthers, however, assents to this conclusion. The former believes that the Grapto- lites did not bear egg-cases at all, but developed them- selves by budding, just as the banks of that oceanic FOSSIL CORALLINES. 45 sea-weed called Sargasswn are formed. In the possession of the cups, perhaps filled with proto- plasmic matter, called nematopkores,rotessor Allman thinks the Graptolites were nearly related to rhizopod animals, and thus included characters now belonging to two well-marked groups of marine animals. - 33- Double Graptolite (Diplograptus pristis). All naturalists are agreed that the rod-bearing Graptolites differed from the "sea-firs" in not being fixed or rooted, as the latter always are. They were therefore free, and no doubt gathered in great banks, as appears from the usual way in which they are found 46 OUR COMMON BRITISH FOSSILS. fossilized. So far, their development by budding after the manner of the Sargassum t or "gulf-weed," would appear to be probable. Mr. John Hopkinson, F.G.S., has shown that Graptolites may be grouped into two great divisions, in one of which a fibrous rod strengthened the outside of the single Graptolites, or was in the centre in the double species. This rod, Nicholson thinks, was originally hollow, and filled in with living material. It must not be confounded, however, with the hollow space (ccenosarc) communi- cating with each cup, which was undoubtedly filled with the " common flesh." The Graptolites which possessed these rods are called Rhabdophores : all of them were free and unrooted. But there is another distinct group of Graptolites of simpler structure, always branched, and " dendroid," or " tree-shaped," like the Sertularians. These are termed Cladophora, by Mr. Hopkinson, who has shown that they were fixed or rooted, like the " sea-firs," and probably were very similar to them. The reader who perceives the nature of the discus- sion which has contributed so many opinions to the natural-history relations of these interesting fossils, will arrive at the conclusion that their nearest living allies are the " corallines," or " sea-firs " (Sertularidce], although they probably had strong affinities with a group of animals even lower in organization than the latter, namely, the Rhizopoda, of which Sponges and Foraminifera are examples. FOSSIL CORALLINES. 47 Mr. Carruthers published a " Revision " (now obsolete, however), in which the leading types of Graptolites are grouped as follows, beginning with Rastrites : In this genus the polypary consists of a simple, slender, hair-like tube, from which project a series of detached cups (Jiydrothecce). (2) The old genus, which was named by Linnaeus Graptolithus. This has given the popular name to the entire group. In it the polypary is simple, and the cups are so thickly grouped along one side that they are all in contact with one another (Fig. 31). (3) The genus named Crytograptus by Mr. Carruthers, in which the polypary grows in one direction, and gives off simple or compound branches at intervals. (4) The genus Didymograptus. In this we have, as it were, a twin Graptolite, of a forked shape, with the cups arranged within the fork (Fig. 31). The symmetrical forms assumed by the coupled branches, or polyparies, are various in different species. (5) Dichograptus ; a bila- terally branched, and rebranched genus of Graptolites. (6) Cladograptus ; another compound or bilaterally branched genus. In this the branches often give rise to other irregular branches, the first part of the name signifying a branch. (7) Dendrograptus is a much- branched, " tree-shaped," and rooted Sertularian-likc Graptolite, with a thick main stem. It belongs to the Cladophora. (8) Diplograptus (Fig. 33). In this the cups are arranged on each side the axis, so as to present the appearance of two single Graptolites 48 OUR COMMON BRITISH FOSSILS. being placed back to back. (9) Climacograptus ; a genus so named by Professor Hall, of America, in which the polypary has a double series of cells hollowed out of the outer covering. (10) Lastly, we have Dicranograptus ; having double rows of cells in the lower part, with branches possessed of only single rows of cups or cells. In the Arenig rocks of Ramsey Island, the dendroid forms seem to be tolerably abundant, and Mr. Hopkinson has shown that these have a nearer relation to the species of Graptolites in the Quebec group of Canada than any other found in Great Britain. The bilaterally branched or double form of Graptolite seem to be peculiar to the Lower Silurian rocks ; whilst the fewer species met with in the upper strata are usually of a simpler character. Some compound forms seem to have attained great length ; thus, a species of Pleurograptus has been traced over three feet long, although even this does not seem to have been the full size. The Skiddaw Slates were formerly believed to form the lowest horizon where the Graptolites were met with, but Mr. Hopkinson's discovery of them, lower down in the Arenig rocks, not only extends their antiquity, but, owing to the similarity of type between the Arenig species and those from Quebec, suggests that their geographical distribution into colonies occurred later on through the subsequent geological changes which took place. Still older species of Graptolites have FOSSIL CORALLINES. 49 been discovered by Dr. Callaway, in the Upper Lingula Flags, and one is named Bryogmptus Callavei. Another genus is Clonograptns> found in the Shineton shales of Shropshire. One of the very best hunting-grounds for British Graptolites is Dumfriesshire. That county is largely underlaid by Lower Silurian rocks, originally deposited along the floors of ancient seas as so much marine mud. Little did the numerous Graptolites know that they were forming no insignificant part in laying down the foundations of the " Land of brown heath and shaggy wood ; " a land to be uplifted for ages above sea-levels, on which the storms and atmo- spherical action of thousands of centuries would be expended, until its surface had become carved into hill and dale, lake and valley, gorge and glen, over all of which genius should throw the halo of ever-endur- ing romance ! This wild land teems with as many relics of the semi-barbarous mediaeval human period as it does with primeval fossils. The heroes not only of Scott, but of many an unchronicled feud and deed of daring, have sought shelter in glens and linns where the black shales through which these had been cut were crowded with pyritized Graptolites. At Moffat, for instance, the black shales of the Silurian rocks abound with these interesting fossils. Owing to the softish nature of the shales, and the way in which they allow water to ooze through their joints, many of the glens in them are well wooded, and E 50 OUR COMMON BRITISH FOSSILS. rich in flowering plants. In the shales there Diplo- graptus pristis and Climacograptus rectangularis are abundant, the latter species particularly so. The neighbourhood of Moffat, also, is good ground for Graptolites. Many new species have been recently described from this district. At Hart Fell such forms as Diplograptus pristis, D. foliaceus, D. mucronatus, Dicellograpttis, Dicranograptus sextans, and many other commoner forms occur. In this remarkable region, rendered classic by Burns and Hogg, the geological student cannot cast his eyes in any direction without recognizing some kind of geological agency or another. All the hills hereabout show traces of glacial action, in rounding, striae, or otherwise. Burns' " Craigieburn Wood " lies itself in the heart of the graptolitic shales ; whilst the student of Scott's " Red Gauntlet" will hardly fail to recognize the graphic scenery delineated in that novel, in his additional wanderings after fossils. Birk Hill is one of the best places in Dumfriesshire for Graptolites of all kinds. Glenkiln Burn is another equally good hunting-ground, where, perhaps, the largest specimens of Plenrograpttis are to be un- earthed. Garple Linn, Duff-Kinnel Burn, and Dob's Linn are other rich storehouses of Graptolites. The latter spot is a waterfall sacred to the memory of two Covenanters, who are said to have been much annoyed by Satan. If these two worthy Scots had been looking for Graptolites, they would not have been troubled by such a personage. FOSSIL CORALLINES. 51 These Moffat Graptolite-bearing shales are the oldest fossiliferous strata in Scotland, and they attain a total thickness of six hundred feet. They have been grouped by Professor Lapworth into three divi- sions, called Birkhill shales, Hartfell shales, and Glenkiln shales ; and each division is split up into " zones," marked by the presence of certain charac- teristic species of Graptolites. These divisions of the Graptolite shales have been recognized by geologists elsewhere, as in North and South Wales, etc. The shales in which Graptolites occur are nearly always of a black colour, and these beds are usually distributed in long lenticular areas through otherwise unfossiliferous rocks. Burns' own county of Ayrshire is not without various geological attractions, although the scenic features are not on so grand a scale as elsewhere. In the metamorphosed Lower Silurian slates of Cairn Ryan we meet with abundance of Diplograptus pristis. The Girvan district has long been famous for its Silurian fossils, and recently Messrs. Etheridge and Nicholson have published a splendid monograph upon them. Nearer home, Graptolites are very abundant in the black shales which crop out in the basement of the little gorge on the top of the hill just above Low- wood, on the eastern shores of Windermere, and not more than a couple of miles from Ambleside. They are found on almost every piece of shale, Diplograptus, Rastrites, Graptolithus^ etc., all of them beautifully 52 OUR COMMON BRITISH FOSSILS. pyritized. From the base of the gorge, where these fossils may be hammered out in abundance, we gain a magnificent view of Windermere, set in its rich framework of green woods, greener than arboreal vegetation anywhere else in Great Britain ! The geo- logical eye takes in the rounded rocks which lie out- side the woody belt, and does not pass by the heaps of morainic matter which frequently form the eastern coast-line. Ice-action speaks forth plainly from every part of this district. Of course, the Lower Silurian rocks, so well developed in North Wales, are not in many places bad Graptolite stores. In the easily identified black, slaty shales which crop out in the railway cutting near Conway station, and banks of the Seiont, near Carnarvon, the young collector may find sufficient to satisfy all his cravings. In various places around Welshpool, as at Fflyrnwy, near Llanfair, the flag- stones abound in Graptolites. The slate-quarries of Llansantfraid, Denbighshire, are famous for them, and the geological tourist may find Diplograptus pristis in great numbers, associated with other familiar species. In the black shales which crop out in many places near Builth, and in the bed of the Wye, Dicellograptus and Climacograptus are in profusion. It will be seen, therefore, that in South Wales, as well as the north of the Principality, wherever the Lower Silurian rocks are well developed, and especially where the shales have a black, finely laminated appearance FOSSIL CORALLINES. 53 Graptolites may be looked for with every prospect of their discovery. The black shales at Garth, near Portmadoc, which belong to the Upper Arenig rocks, are in places crowded with Graptolites. The richest locality in South Wales is perhaps Ramsey Island, where, in the dark shales forming the cliffs, there are plenty of Phyl- lograptus, Callograptus, Ptilograptus, and Tetragraptus. The promontory of St. David's is now known to con- tain them, especially at Llanvirn and Whitesand Bay Abereiddy Bay is a good locality for finding Didymo- graptus and Dicellograptus. At Tarannon, in North Wales (a lovely neighbourhood to select for a walking- tour), no fewer than twenty-three species of Graptolites have been met with, distributed through five genera. The Skiddaw and Keswick district is usually rather poor in fossils, although to the geologist this is atoned for by the physical geology being among the most interesting examples in Great Britain ; whilst for beauty and diversity of scenery, it would be difficult to find its equal in our land. In the black slates, the geological student should look closely for Graptolites. No fewer than twenty-seven species have been obtained thereabouts. At Coniston, in the easily recognized " mud-stones," we find another colony of Graptolites, of which twenty-five species have been described. The Ludlow shales, in the Upper Silurian rocks, saw the last of this ancient and easily identified group of fossils. Only one genus of the Rhabdophora 54 OUR COMMON BRITISH FOSSILS. (Monograptus) is there represented, but eight species have been recognized as belonging to it. Of the Cladophora there are several species of Dendrograptus and Ptilograptus. The Wenlock shales are the home of CyrtograptiiS) which may be found at Builth, and in the Pentland Hills. At Key's End Hill, Malvern, and also near Port- madoc, we find an abundance of another pretty fossil coralline called Dictyonema sociale. In the Carbon- iferous rocks we find Palceocoryne, and other probable corallines. Graptolites must be sought for where the black shales crop out, and these are usually amid the grandest or the prettiest and loveliest bits of river, hill, and mountain scenery. Nature holds forth charms of her own to tempt the geological student from the busy haunts of men to the quietest parts of her sanc- tuary, where she deigns to unfold the mysteries that were originally hidden for him when "the foundations of the earth were laid." 55 > CHAPTER III. FOSSIL CORALS. PERHAPS no fossils have such a geological value as corals. If extinct species were marked by the same habits as their modern representatives (and in many cases the families of living corals are so ancient, and the extinct forms glide so imperceptibly into existing kinds, that there is no absolutely strongly marked line of division), then their value to the physical geologist who endeavours to restore the conditions of primeval seas is immense. For coral-animals can only flourish where the sea-water is clear, and therefore where no muddy sediments are forming. Coral-animals are easily separable into two groups the single or simply compound corals, which are usually inhabitants of deeper water ; and the reef-building corals, which cannot live and flourish beyond the depth of twenty- five fathoms. Moreover, according to Darwin, coral reefs indicate to the physical geographer slowly sub- siding areas of the sea-floor. They are also indicative of a certain degree of ocean temperature, for we do 56 OUR COMMON BRITISH FOSSILS. not meet with them where the sea-water is cooler than 62, and therefore the sub-tropical belts of our globe now roughly comprehend their distribution. But we find fossil corals of all kinds simple, compound, and reef-building. They are characteristic of many thick limestone formations, from the Silurian upwards. We have in the British Islands abundance of fossil reef- building corals, where their modern representatives could not now live. What climatal changes these Fig. 34- A, Dendrophyttia, a compound Coral ; B, Caryophyllia, a recent Coral. valuable fossils indicate ! Not less important are the conditions of the ancient seas they lay before us. We carry our minds back to a period when there were coral islands, fringing-reefs, and barrier-reefs in British seas. These reefs also tell the geologist of the adjacency of land, and inform him of the fact that the sea-floor was in a state of subsidence. Moreover, few fossils are prettier, more easily pro- curable, or look better in the cabinet, than corals. FOSSIL CORALS. 57 They are found in nearly every marine limestone formation. No other fossils can be so well studied, cut into sections, and examined under the microscope. And they are so very abundant that the limestone OUR COMMON BRITISH FOSSILS. walls in the hilly districts where Silurian, Devonian, Carboniferous, or Oolitic limestone crops up, are often composed of little else than blocks of fossil coral. We are beginning to understand the true relationship of living and extinct corals better than we did, thanks to the labours of Dr. Sorby, Professor M. Duncan, and Professor H. N. Mosely. Formerly these animals (classified chiefly by the stony or limy parts they leave behind) were all grouped among that order of the Actinozoa called Zoantharia, of which the common Fig. -^.Favosites Gothlandica: e, cluster of tubes of Favosites; d, tubes (magnified), showing tabulae and perforations connecting the tubes. sea-anemone is a type. The order Zoantharia was split up into three divisions, called Tabulata, Rugosa, and Aporosa. It was thought the two former were Palaeozoic types of corals, and the third of Neo- zoic and Recent corals. Let us examine the funda- mental difference of these three groups. The tabulate corals are remarkable, and, indeed, obtain the name which distinguishes them, for the partitions which seem horizontally to split them up into chambers. FOSSIL CORALS. 59 They are compound corals, whose shapes are modified by the manner in which they grew, so that some are polygonal, or many-sided, and others oval or round. Fig. 37. Syringifora ramulosa, a common Carboniferous limestone Coral. The most remarkable of these tabulate fossil corals are Heliolites, Favosites, the pretty " chain-coral " Fig. 38. Heliopora ccerulea, a recent Alcyonariai. Coral. (Halysites\ Syringipora, etc. It will be seen from Fig. 36, which shows a magnified section of a very 60 OUR COMMON BRITISH FOSSILS. abundant Silurian coral (Favosites Gothlandicd] y that the coral-pipes as we may call them are separated into horizontal chambers. The walls are perforated as they are in some of the Alcyonaria, possibly for transverse canals. It will also be seen that the interiors of the corals are not radiated that is, have not those vertical plates springing from the walls which are called septa; or, if they are present in Tabulate corals Fig. 39. Millepora alcicornis, a recent Hydrozoan Coral (Bermudas). they are very feebly marked. This general absence of septa is the leading distinction of Tabulate corals. Professor Mosely thinks that most, if not all, of this group are in reality not Zoantharians, or true corals, but Alcyonarians, of which the recent common Organ-pipe coral (Tubipora musica) is the best example. Some of the so-called corals, as the Millepores, he proved FOSSIL CORALS. 61 not to be corals at all, but demonstrated they actually belong to another class, the Hydrozoa. In other words, they are the remains of colonies of animals allied to Sertularians, but possessing limy structures, instead of the chitinous or horn-like material which composes the solid parts of our " sea-firs." Professor Mosely shows there is a peculiar division of labour in the polyps of Fig. 40. Section of " Chain-Coral " (Halysites catenulatus), showing tubes (Upper Silurian formation). modern Millepores, some of the zoophytes catching the food and others digesting it, after they have received it from the catchers. This is the case in Stylaster, where the food-catching zoophytes much resemble the tentacles arranged round the mouth of the common sea-anemone. The abundant recent coral Heliopora ccerulea 62 OUR COMMON BRITISH FOSSILS. (whose specific name comes from the bright blue colour of the stony structure, which in other modern corals is usually white) is an Alcyonarian, more nearly related to some sea-fans than to true corals, It is plentiful in equatorial seas, and especially off the Bermudas. It has not indistinct traces of septa. The genus of fossil corals called Heliolites, abundant in Fig. 41. " Chain-Coral " (Halysites catenulatus), as usually found intact in round masses. the Silurian and Devonian limestones, does not differ in any important particular from the living Heliopora, and, like it, no doubt belonged to the Alcyonaria. The division of fossil corals called Rtigosa, on the other hand, is distinguished by well-marked septa, radiating from the coral walls towards the centre, in the pretty star-shaped fashion which caused Cuvier to FOSSIL CORALS. group these objects, along with others similarly star- rayed in their shapes, into the sub-kingdom Radiata^ now no longer accepted by naturalists. In this radiated structure, therefore, the rugose corals re- Fig. 42. Horizontal section across block containing Lithostrotion junceum (Carboniferous limestone). Fig. 43. Vertical section of Lithostrotion junceum. Fig. 44. Amplexus coralloides (Carboniferous limestone). semble the aporose corals. But whereas the tabulate and rugose corals (with few exceptions) are limited to Palseozoic rocks, the aporose corals are peculiar to OUR COMMON BRITISH FOSSILS. those formed since then. Again, the septa, or radi- ating plates, of the rugose corals are in multiples of four, whilst -those of aporose corals are in multiples of six. Besides this means of distinguishing the aporose corals from any of the others, the fact that they never have tabula that is, are not divided into hori- zontal layers is another important distinction. When Fig. 45. Horizontal section of Litfio- strotion Phillipsii (Carboniferous limestone). Fig. 46. Vertical section of A mplexus coralloides, showing the tabula. the tabulate corals have only faint traces of septa, we can still see they are in multiples of four, and they thus show their structural relationship to the Rugosa. Dr. Sorby has shown that the tabulate corals are built up of calcite, whilst the Neozoic and modern corals are formed of that limy structure known as arragonite. It may be that the Rugosa are descended from the FOSSIL CORALS. 65 Tabulate which would at once make it clear why the tabulate corals appear in such numbers of species and individuals in the Silurian and Devonian seas. In the Carboniferous rocks the most numerous corals are the rugose kind, in which the radiated structure is very plainly visible, as in Lithostrotion junceum, etc., of which we give illustrations of the transverse appear- ance they present when cut and polished. For some of my illustrations I am indebted to Mr. James Thomson, F.G.S., of Glasgow one of the most Fig. 47. Horizontal section of A titplexus Fig. 48. Cyathaxinia (Carboniferous coralloides, showing feebly developed septa. limestone). A, horizontal section. enthusiastic and diligent students of Palaeozoic fossil corals in Europe. I have already said that the numerously represented fossils called Stromatopora abundant in our Silurian and Devonian limestones are now believed to be calcareous sponges, or sponges whose abundant limy spicules amalgamated into the concentric rings characteristic of their structure. This structure may be studied in any polished mantelpiece formed of Devonian marble from the quarries of Newton Abbot and the neighbourhood. By far the prettiest of the Palaeozoic fossil corals are those F 66 OUR COMMON BRITISH FOSSILS. belonging to the Rugosa, such as Strombodes, Cya- thophylluni (perhaps the most plentiful of them all), Cyathaxinia (a simple coral), Lithostrotion, Lit ho- dendron, etc. Perhaps the single coral which may be regarded as the simplest in structure is Am- Fig. 49. Recent Arborescent Perforate Coral (Ocuh'na. axillarts). plexus, and there is reason for believing that many more elaborate fossil corals pass through a kind of Amplexus stage. A fourth division of corals is termed Perforata (Fig. 49.) These are the familiar twig-like, branched FOSSIL CORALS. 67 corals, whose surface breaks out here and there into flower-like calyces, and whose tips usually terminate in the same sort of objects. The entire structure is dis- tinguished by its light and porous character whence the name of the group. In spite of their apparent fragility, we find them living amid the most violent of seas, for their rapid growth enables them to withstand the destructive effects which would other- wise break them up. The division Aporosa did not Fig. 50. Astrcea rotulosa, a recent West Indian compound Coral. make its appearance in Primeval seas, but is first observed in strata of the Secondary period, although its species are most abundant in the present epoch. The Perforata are feebly represented among primary fossils by Silurian and Devonian genera, such as Protarea and Pleurodictyum. Perhaps the modern Perforata are better known by their common name of Madrepores. 68 OUR COMMON BRITISH FOSSILS. The intervening spaces in the branched or arbore- scent corals, between where one flower-like calyx is seen and another, is called the ccenenchyma. They are the equivalents of the "inter-nodal spaces," or distances which separate leaves from one another, in the branches of a tree. It is the rapid porous growth of these parts which enable such compound corals to Fig. 51. Astraafavosa, a recent East Indian Coral. stand against a good deal of marine wear-and-tear. It is these parts, also, which bind the various corallites together into one colony. In deep-sea corals this ccenenchyma rarely exists as a means of rendering them compound, but a different method of "com- pounding" takes place. Oculina is said to be the only large coral now found in northern seas ; but our FOSSIL CORALS. 69 British rocks, especially the Carboniferous limestone, are in places almost entirely composed of corals, reef- building, deep-sea, and shore-loving species. There is often a difficulty in recognizing which of the fossil corals were "reef-builders," and which were not. For it does not follow that because the fossil corals are of a compound character they were therefore engaged in the work of reef- building. Perhaps the safest plan is to trace the existing genera of reef-builders as far back in geological time as we can, or at any rate to compare the fossil kinds with their nearest living representatives. Few genera are more distinctively " reef-builders " than the Astrcea, whose characteristic star-like arrangement of polypes or corallites (the latter often so close together that they press each other into oval or polygonal shapes), has given to this genus its distinctive name. The wide- spread geographical distribution of the genus Astrcea, and the fact that it is engaged, in areas separated by enormous geographical distances, in reef-building, would be an incidental proof to a geologist of its geological antiquity, even if this genus were not found in our Upper Silurian and Devonian limestones. Thus Astrcea rotulosa (Fig. 50) is a living species of this interesting genus of corals found abundantly in West 70 OUR COMMON BRITISH FOSSILS. Indian seas, where it is met with in coral-reefs, and masking and adhering to natural rocks. Astrcea favosa (Fig. 51), on the other hand, is peculiar to the East Indian seas, where it is hardly less abundant. Astraa ananas (Fig. 52) is a common fossil in the Silurian limestone at the Wren's Nest, Dudley, in the formation of which we can hardly doubt that it and Fig. 53. Lithostrotion basaltiforme, an abundant compound Rugose Coral in the Carboniferous limestone. The lighter parts show the transverse structure, as seen when the coral is cut for sections. its compeers took a considerable part. For Professor Owen tells us that the Wenlock Edge, in Shropshire, belonging to the same formation, is nothing more or less than an ancient coral-reef thirty miles in length ! The Plymouth limestone belongs to the Devonian period, and in it we find this and other genera of reef- building corals ; and many of our best palaeontologists FOSSIL CORALS. 71 are of the opinion that this limestone is nothing more than a Devonian coral-reef skirting the old land- regions composed of Cambrian and Silurian rocks. Hunting for fossil corals in the older rocks implies visits to some of the most picturesquely romantic spots in Great Britain, with here and there a little variation in some localities whose ancient loveliness Fig- 54. Vertical section of Lithostrotion PJiillipsii, showing tabulae. has had to give way to the deforming ugliness of extensive mining or manufacturing operations. This is the case with the Wren's Nest, near Dudley, formed of a romantic cluster of highly inclined Upper Silurian limestones rising from beneath the Coal formation which extends up to their very base. These limestone 72 OUR COMMON BRITISH FOSSILS. slabs are hard, as if the soft organic matter of the molluscs and corals, whose hard parts almost wholly make up the rocky mass, had thoroughly permeated Fig. 55. Clisiophyllum, a single fossil Coral, characteristic of the Carboniferous limestone formation. it, and thus produced a similar induration to that effected by sculptors, when they boil their porous plaster casts in oil to render them tougher and more durable. But hard as the Dudley limestone is, the FOSSIL CORALS. 73 fossil corals are harder, and as the faces of the slabs are weathered, the fossils stand out in high relief. To a young geologist who is fleshing his maiden hammer, such a sight as is here presented produces an effect not likely to be forgotten during life. Myriads upon myriads, here lie entombed the exuviae of primeval seas ! No museum in the world could attempt to vie with these almost bare or lichen-covered slabs for variety and abundance of organic re- mains. Hours can easily be spent in climbing from crag to Fig. 56. Transverse section of Cli- Crag, in and OUt Of the brUSh- siophyllum, showing (in part) details of structure. wood which is irregularly growing where the layers of soft slate are intercalated between the limestone slabs ; and one forgets that the wide-stretching plain at the foot of the " Nest " is superficially crowded with ironworks, manufactories of all kinds, forests of chimneys (many of them out of the perpendicular), colliery works in various stages of mining development as to the modern character of their pit gear, and densely packed regular or irregular rows of unpicturesque-looking houses. The walls of the old castle look over this modern scene of energy and mechanics ; and the old and the new, even in human history, are thus brought into strange juxta- position. 74 OUR COMMON BRITISH FOSSILS. Leaving out other fossils, the student may find at the Wren's Nest, or in the quarries opened in the lime- stone, abundance of such corals as Favosites Gothlan- dica, F. polymorphci) etc., and various species of such characteristic Silurian corals as Omphyma (in great abundance), Cystifhyllum, Porites, Heliolites, Palceocy- clus, Columnaria, Halysites (the well-known and very plentiful " chain-coral "), Strombodes, Cyathophyllum, Fig- 57. CaryopJiyllia, a recent British Coral (natural size). etc. Not only is there an abundance of species of fossil corals, simple and compound, but of genera and species as well. Compared with this wealth of Zoan- tharian life, our modern seas are quite poverty-stricken. All that even the warmer waters of our Devonshire and Cornish coasts can now support are a few pretty but insignificant corals, the largest of which is Caryo- phyllia, a genus which first appeared in the seas of the FOSSIL CORALS. 75 globe during the formation of the Wenlock limestone, and has been in existence ever since. Another recent British coral is the little Balanophyllia regia. Both these British corals may be seen in the living state in the small table tanks at the Crystal Palace and Brighton Aquaria, and a brief examina- tion of them will enable the Student tO form a gOOd idea Of Fig. &.--Bcaanoph y ma. regia, a recent British Coral (natural size). how the hard calcareous sub- stance which remains as " coral " is secreted by the investing flesh. He will also be able to restore, in imagination, the vivid and many-coloured appearance presented by the sea- floors of the Palaeozoic epoch, when corals were so abundant, from the tints and colours which characterize the flesh of living coral-animals. A quieter place for fossil coral-hunting than Dudley is the neigh- bourhood of Wenlock, in Shropshire, where that division Of the Upper Fig. 59. OmphymasubturMnata, a common Silurian fossil Coral. Silurian formation called " Wenlock limestone" crops up, and whence it has derived its name. No better place would be 76 OUR COMMON BRITISH FOSSILS. found for a short tour, and fossil-collecting might be agreeably diversified by a little archaeology, which the old Norman abbey, etc., of the town would afford. All the fossil corals mentioned as abundant at Dudley are also to be found in the neighbourhood ofWenlock, with the addition of the beautiful Lonsdalia Wen- lockensis. Benthall Edge, about two miles distant from Wenlock, is a famous place for fossils, and Fig. 60. Section of Favosites cervlcornis, an abundant Devonian Coral corals are there especially abundant, and in excellent preservation. It overlooks the Severn, and the busy but still picturesque Coalbrook Dale. Wenlock Edge is interesting to the physical geologist, for it stands up from amid the softer Wenlock shale. As might be expected, the greater ease with which the latter has yielded to weather action has caused it to be denuded into the plain which it now underlies. How abundant the fossil corals are in the limestone here FOSSIL CORALS. 77 may be gathered from Professor Owen's statement just referred to, that " Wenlock Edge is itself a coral- reef thirty miles in length." Nearly all the fossil Upper Silurian corals figured and described by Edwards and Haine in the publication of the Palaeonto- graphical Society are found in the neighbourhood of Wenlock. There are plenty of quarries about, and the student finds abundance of materials of all kinds. From Wenlock, the geological wanderer makes Fig. 61. Stenopora (or Favo$ites)fibrosus, an abundant Silurian Coral. his way to other classic grounds, whose names are famous to the reader of " Siluria." The various sub- divisions of the upper beds crop out over a large extent of Salopian country. Among localities to be specialized is Aymestry (a place which has given its name to one of the uppermost Silurian beds). Craven Arms station, near Church Stretton, is a capital place for the student to make for, if he wishes to be placed at once on Silurian ground. The Aymestry limestone 78 OUR COMMON BRITISH FOSSILS. is seen forming the bold hills of View Edge and Stokesay camp, and the limestone in places literally abounds with the well-known and characteristic fossil brachiopod Pentamerus Knightii. The Garden House quarries at Aymestry are capital collecting grounds. Indeed, a good many of the fossils figured by Sir Roderick Murchison in his " Silurian System " were obtained at these quarries. Nearly every village in the neighbourhood has several outcrops of or quarries into the rocks, where fossils may be abundantly hammered out. The commonest of the fossil corals are Cyathophyllum (often well known among the quarrymen and others by the name of "petrified ram's horns," in allusion to the irregular way in which the stony corallum usually twists), Heliolites inter- stinctus, Haly sites, and Ompkyma (one species of which, O. subturbinata, is a very widely and plentifully distributed Silurian coral). The Malvern Hills also afford several noticeable localities where the Silurian strata yield fossil corals. In Eastnor Park, just beneath the picturesque Herefordshire Beacon one of the loveliest spots in that picturesque district we have hammered out some splendid corals. Should the geologist pedes- trinate this park towards the end of March, he will see such a wealth of wild Daffodils as even Words- worth's poem does not give the faintest idea of! The Woolhope Valley should also be mentioned, and here the commonest corals to be exhumed are FOSSIL CORALS. 79 Omphyma (several species), Cyathophyllum, Halysites, ZaphrentiS) Astrcza, etc. The best localities there- abouts are Checkley Common, Dennington, Warslaw, and Dormington (the limestone at the latter place appears to be simply an ancient local coral-reef, crowded with " chain-coral " and Favosites Gothlan- dica ; it is wonderfully full of fossils of various kinds). At May Hill there are several quarries, in which the fossil " chain-coral " (Halysites catenulatus) and Favo- Fig. 62. HettoKtes interstinctus, a common Silurian Coral. sites gothlandica are abundant. The Silurian rocks of the Malvern Hills are nearly everywhere plentiful in fossils, although evidences of the reef-building corals only occur here and there. The following are all capital collecting grounds : Netherton Valley, Stones- way, about Nenning's Farm, Colwall Copse, the quarries along the Marthon road, Hartley, and Blais- don Edge (where extensive quarrying of the Wenlock 8o OUR COMMON BRITISH FOSSILS. limestone is carried on). Nor should the picturesque town of Ledbury be neglected with quietest of old English suburbs, the whole town set in a framework of woods and wooded hills. The latter are frequently pierced by quarries, from which numbers of fossil corals, characteristic of the Upper Silurian formation, may be obtained. To feel Fig. 63. Portion of Heliolites inter- llOW deliciOUS is the quiet stinctus magnified, to show corallites. seclusion of a town like this, the pedestrian should enter it about two o'clock some summer's afternoon ! The lateral foldings of the Upper Silurian strata of North Wales have frequently obliterated the organic remains, or left them represented by only feeble im- pressions. Of course, except a few single and solitary corals, we should not expect to find nor do we find fossil corals abundant in any other than limestone deposits, all other strata being formed in more or less muddy water, as the nature of the sediments shows ; whilst coral animals are noted for their love of clear water, and their dislike to turbid. Hence in such beds as the Bala limestone we frequently find abundance of fossil corals. One of the best localities I know of in North Wales is Mynydd Fronfrys, a few miles from Llangollen. In an old quarry along the Oswestry road FOSSIL CORALS. 81 there is a perfect feast of fat things in the shape of abundant and beautifully preserved Silurian fossils; and the spot is so quiet, and in the midst of such delightful and little-visited V/elsh scenery, that my readers would be thankful for directing them to the place, if it were for that alone. The Coniston limestone, which runs an irregular course through the Lake District, is in places full of fossil corals, as at Sunny Brow and Long Steddale. In the neighbourhood of the little town which gives to this stratum its name, may be obtained Monticulipora, Stenopora (or Favosites] fibrosus, Petraia, the latter now known to be only natural casts of Cyathophyllum, etc. The fossil coral Heliolites megastoma found in this bed is remarkable for its well-developed septae. Some lovely spots may be found where there is good geologizing on these beds. One of the best I know is on the road to Troutbeck, near Windermere. This road crosses the hill where the limestone crops up, and the walls by the roadside are formed of the local rock. They are perfect museums, but, numerous though they are, all the fossils occur as casts or im- pressions ; and the rock is often quite " rotten " from the abundance of these casts. This is due to the lime (which formerly entered into the composition of the fossils) having been gradually dissolved away by the rain-water which has been percolating these fossiliferous rocks ever since they were converted into dry land. Among the most abundant of the G 82 OUR COMMON BRITISH FOSSILS. fossils is Favosites fibrosus, perhaps the oldest known British species, and one of the widest distributed of all Silurian corals. Many varieties of it are known, and among others one which is seen encrusting univalve shells as if it had destroyed them, after the fashion which is still practised by some mechanically parasitic zoophytes in modern seas. The stone walls on and about breezy Applethwaite Common are often full of small kinds of fossil corals, as impressions of Cyatho- phylhim, Favosites, Heliolites, etc. The Caradoc rocks contain by far the largest number of species of fossil corals of any of the older Palaeozoic rocks, about forty-two different kinds having been described. One remarkable fact concern- ing these ancient corals is that we often find one genus represented by only one species. This is par- ticularly the case in the Upper Llandovery rocks, where, out of sixteen genera of fossil corals, no fewer than eleven have only one species each. A very rich development of corals seems to have taken place during the period when the Upper Silurian and Middle Devonian limestones were de- posited. No fewer than seventy-six species have been obtained from the Wenlock rocks of Great Britain alone ; whilst from the Devonian strata fifty- two species have been catalogued. The Carboniferous limestone, however, appears to have been deposited when the ancient coral fauna had reached its greatest development, for one hundred and forty-one FOSSIL CORALS. 83 species have been enumerated from this formation alone ! These numbers, however, do not convey to the mind of the student such a clear idea of the relative abundance of fossil corals in the older rocks, as he can get for himself by geologizing in two or three localities where corals are abundant. Mr. Etheridge thinks that during no period in the physical history of the British Isles has there been such a remarkable assemblage of corals as when the Middle Devonian rocks of North and South Devon were formed. Out of fifty-two species not one passes to the Carboniferous formation, and none are common to the Silurian rocks of any area. The limestones of Torquay and Newton Abbot are simply Devonian coral-reefs of great magnitude. Some splendid geologizing may be obtained in the neighbourhood of Girvan, in Ayrshire a rather com- plicated tract of Upper Silurian rocks. The district is a pleasant one to work in, with the Atlantic on one side, and the hilly sheep-pastures on the other. Numerous quarries may be found, and pleasant little adventures made along miniature gorges cut by the "burns," where we hammer at the rocks which crop out. Within six or seven miles of Girvan there are at least forty good fossilizing spots. The best of them is Woodland Point an exceedingly rich treasure-house of Silurian fossils. Here many corals may be collected, such as Heliolites, Plasmopora, 84 OUR COMMON BRITISH FOSSILS. Halysites, Favosites, etc. One common fossil coral is evidently peculiar to this neighbourhood, and has been named by Messrs. Nicholson and Etheridge (who have published a valuable work on the Girvan fossils) Favosites Mullochensis. This fossil coral is also common at Mulloch Hill, near Girvan whence its specific name. Many other fossil corals are obtain- able at Mulloch Hill. The Wenlock limestone at Marloes Bay, Pem- brokeshire, contains some good fossil corals. In Ireland, Silurian corals are to be met with in greater or less abundance at Dingle, Bull's Head, Cahercouree, Ardaun, Kilbride, Cong, and Ferriter's Cove. The neighbourhood of Tortworth, in Somerset- shire, has long enjoyed a geological reputation for its fossil corals ; Cuttimore's Quarry, perhaps, being the best. The country about Old Radnor abounds with them. The quarries at Mocktree, not far from Ludlow, abound in Silurian fossils generally, and in corals especially ; and the student will be delighted with the lovely scenery of the country round about. I have alluded to the corals of the Devonian rocks. These do not weather out or knock out so readily as the corals from the Silurian and Carboniferous lime- stones. The interstices of the Devonian corals, as well as their matrices, are filled in with compact sedi- ment, so that we are forced to cut and polish slices to discover their structures and relationships. Very beautiful is a collection of these polished sections, FOSSIL CORALS. 85 owing to the lovely and variable tints of the lime- stone, which range from grey to yellow, pink, and red. Thin slices mounted on glass for the microscope form exquisite objects. The student may obtain for himself any quantity of coralliferous rock in and about Torquay. By moistening the dried and perhaps worn surface of the rock, the included corals become plainly visible. Devonian corals are also obtained at Plymouth, Teignmouth, and Ilfracombe. Speaking of British fossil corals, perhaps it would be impossible to direct the student to richer fossili- ferous deposits than the lower Carboniferous strata of Scotland. Mr. James Thomson, F.G.S., is of opinion that their abundance in Scotland is due to the strata of the latter having been deposited in shallow water, whilst the English Carboniferous or " Mountain " lime- stone was laid down in deep water. But the great thickness of the limestone in Derbyshire (about four thousand feet) indicates a depression of the sea- floor all the time the beds were forming ; for its mineral characters would have been altered if it had simply filled up an ocean basin to that depth. As we have already seen, a gradually lowered sea-bed has been stated by Darwin to be necessary to continuous coral growth. Of all the Carboniferous corals the genus Zaph- rentis is one of the most widely distributed and generally abundant. It is usually found in a very perfect condition, and may often be seen in the walls 86 OUR COMMON BRITISH FOSSILS. in limestone countries, so weathered that it stands out in high relief. This coral is not only abundant where- ever the Carboniferous limestone occurs in Great Britain, but it is also distributed through the strata Fig. 64. Fossil Coral (Dibunofhyllnm}. Fig. f>$.Zaj>hrcntis. from the bottom to the top, although the smallest specimens are usually found in the upper beds, and the largest in the lower. The fact that it is plentifully found where shale bands occur shows that it affected shallow water, for shale is a muddy deposit. At Swansea Zaphrentis cylindacea occurs more than Fig. 66.-Transverse one foot in length, and three and a half inches in diameter. The genus Dibunophyllum (Thomson) differs from Zaphrentis in the structure of its calycle or cup. This coral, and other genera such as Rhodophyllum, Koninckophyllum.Aspidophylhim, Clisiophyllum, Histiophyllum, Cyclophyllum, are found most abundantly in the lower strata of the Scottish section of Zaphren- tis, cut through upper figure at the point traversed by a line. FOSSIL CORALS. 87 Carboniferous limestone system. Beith, in Ayrshire, and Dunbar, Haddingtonshire, are capital collecting grounds for all the above-mentioned fossil corals ; and I may add that they are in a better state of pre- servation at Beith than anywhere else in the United Kingdom. Aspidophyilum occurs in abundance in the limestone of county Down, Ireland ; and in the pic- turesque, terrace-like outcrops of the Carboniferous limestone strata at Blackhead, county Clare, both this and several other genera of corals are plentiful. Fig. 67. Vertical section of fossil Coral ( Kon inckophyllum} . Fig. 68. Transverse section of fossil Coral (Koninckophyllutn) in part snowing cellular structure. Lonsdalia (which obtained its name after the early geologist) is another abundant Carboniferous coral. It is very common in the neighbourhood of Mold, and may be extracted from the walls by the roadside in wonderful perfection. The uppermost beds of the fine escarpment of limestone called Eglwyseg at Llangollen, in North Wales, also contain it in large quantities. Indeed, we may regard that stratum as 88 OUR COMMON BRITISH FOSSILS. one of the finest Carboniferous coral reefs in Great Britain. There are many species of Lonsdalia, of which rugosa and floriformis are perhaps the most beautiful as well as the most abundant Both show structure in the clearest manner, and thin sections of them, either transverse or horizontal, form exquisite low-power objects for the microscope. The follow- Fig. 69. Transverse section of Lonsdalia rugosa. ing are among the British localities where different species of Lonsdalia may be obtained : Ecclefechan, (Dumfriesshire), Boghead, Lesmahago, Clifton (near Bristol), almost every part of Derbyshire where the Carboniferous limestone crops up (but particularly near Castleton), and in the Welsh localities above mentioned. At Hafod and Boghead this fossil coral is found in very large masses, in a capital state of preservation. Lithostrotion (Figs. 42, etc.) is a widely diffused FOSSIL CORALS. 89 genus. Carboniferous limestone rock is frequently composed of its dense clusters of corallites, in masses, looking like so many bunches of twigs. Lithostro- tion junceum is perhaps the commonest species. In Derbyshire Lithostrotion arachnoideum forms large masses of the limestone. When these corals weather out, they stand in relief on the stones, as if the latter were covered with dead ivy twigs. The Carboniferous limestone rising behind the pleasantly situated town of Kendal, in Westmoreland, is rich in corals, Cyathaxinia being more abundant there than in any other English locality I know of. For immense variety of corals, however (associated with other fossils), and for the chance of picking up some good, rare, and, it may be, new things, commend me to the little quarry which has long been worked in the outlier of Carboniferous limestone at Hafod, about two miles from Corwen, in North Wales. The tourist will easily find it by taking the pretty foot- path by the River Dee just here almost at its best as regards lovely scenery. Having found the quarry, he will be safe for a few hours at the least. There is an abundance of the elegant coral Phillips astrea. If the student's eyes are open, he may read off the story of that ancient coral-reef and its fauna without much fear of drawing false inferences. Clitheroe is good for all the fossils of the forma- tion I am speaking of; and at Bolland about four or five miles off, in a very lovely and richly wooded 90 OUR COMMON BRITISH FOSSILS. part of the country there is a classic ground for fossil corals. The Permian has yielded very few fossil corals. Chcetetes is said to be found at Humbleton Hill, Durham. When we geologize on the limestone beds of the Secondary formations we lose sight of the old-fashioned types of coral, whose generic names by this time have become almost as familiar in our mouths as house- hold words, and we are suddenly introduced to new forms. Many of them are very persistent through the Lias and Oolitic rocks, although other kinds are peculiar to the Chalk. Coral-reefs were abundant in British areas during both the Liassic and Oolitic periods, but not when our White Chalk was formed. The latter appears to have been deposited in deeper water than coral-reefs are built in, and we find the Cretaceous corals are therefore usually of single, non-reef-building kinds. Chief among the genera of the earlier Secondary corals are Thamnastraa, Latimceandra, Isastrcea, The- cosmilia, Montlivaltia, Septastrea, Leptophyllia, etc. The latter is plentiful in the Lias rocks in the Isle of Skye, associated with Isastrcea. The number of localities where Lias corals may be obtained is very great. Cowbridge, in Glamorganshire, is one of the best. The visitor to Shakspeare's birthplace at Strat- ford may hammer them out of the beds at Watford Hill, or find them loosely lying on the surface. Fre- FOSSIL CORALS. quently the latter is the best way of getting them, as the shale weathers, and the corals imbedded in it get liberated. At Cherrington, near Shipston-on-Stour, very numerous and fine specimens are picked up off the fields ; Montlivaltia Victories (perhaps the largest of our simple fossil corals) is not uncommon. Brocastle, Ewenny, Marton near Gainsborough,Larne near Belfast, Fenny Compton in Oxfordshire, Harbury, Aston- Magna, Down-Hatherley, the neighbourhood of Lyme Regis, Ilminster, etc., are places where Lias corals can be obtained more or less abundantly. In the Inferior Oolite at Crickley, East Coker, Painswick, Dundry Hill near Bristol (a splendid fossil hunting- ground for fossils of various sorts), Leckhampton, Isastr- both star-fishes and sea-urchins belong, range to and continue over deep parts of the ocean-bed, more than any other group of marine animals. Thus, during the deep-sea dredgings of the Challenger, such genera as Ophiomusium, Archaster, etc., were dredged up, the latter from more than a mile and a half depth of 136 OUR COMMON BRITISH FOSSILS. Fig. 1 14. Fossil Marstoni] (Lower Ludlow rocks). sea-water. A large star-fish, called Leptychaster, allied to our Luidia, was brought up off Cape Maclear, Kerguelen's Island, in very deep water. Another genus, Hymenaster, was found widely distributed over the sea-floor, and at depths ranging from about half a mile to more than three miles. Star- fishes and their allies, the sea-urchins, are usually the commonest fossils of the Chalk formation, which was an oceanic deposit formed under similar circumstances to the "globigerina ooze" of the Atlantic. Dr. Wallich showed (when sounding in the Bull Dog for the first Atlantic cable) that the ocean floor was occupied by star-fishes, for these animals came up attached to the sounding-lead, and this incident first broke people's faith in the old-received notion that absence of light in the deep sea rendered it a desert for all animals except the Protozoa. The Asteroidea (represented by our common " five- fingers "), and the Ophiuridea or " brittle-stars," as we have said, are found in Cambrian rocks. Specimens are often better preserved in the fossil state than dried recent specimens usually are in museums. Sea- urchins also lived in the Palaeozoic epoch, but they do FOSSIL STAR FISHES AND SEA-URCHINS. 137 not appear to have thriven well. Only two genera are known, and these are represented by few species during periods long enough to form strata thicker than all the Secondary deposits taken together. But when we come to the Secondary period, we find the sea-urchins gaining ground. By-and-by, as in the Chalk formation, they are wonderfully common, and of multitudinous shapes and types. But by this time Fig. 115. Recent Ophiocoma (British seas). the Encrinites, which we have seen were so plentiful on the floors of primaeval seas, had begun to decline. Broadly, therefore, it may be stated that the sea- urchins began to flourish just when the Encrinites commenced to dwindle away. Fossil star-fishes are not as a rule abundant, unless, perhaps, we except a particular stratum in the Middle Lias, where they are in places so plentiful 138 OUR COMMON BRITISH FOSSILS. that the seam is called the " star-fish bed." The oldest and chief forms are P rotas ter, Palceaster, Urastella, Palceasterina, and Palceocoma, the latter being related to our living "bird's-foot star-fish." At Leintwar- dine, where the Lower Ludlow rocks crop up and are quarried, we meet with both the kinds of fossil star-fishes of which we have been speaking. Speaking of Protaster Miltoni (one of the ancient "brittle- stars "), Mr. Salter says it is " abundant, and of all sizes," meaning, I suppose, in various stages of growth. Few localities are better worth a geological pilgrimage than this part of Shropshire. It is only nine miles from Ludlow, where the celebrated " Bone- bed" of the upper Silurian rocks may be advan- tageously studied. The Lower Ludlow rocks at Leintwardine are not much quarried, for they are a kind of "mud-stone," of little commercial value. Otherwise there is no doubt the number of fossil star-fishes which would be exhumed would be im- mense. Unfortunately, since Mr. Salter's time, the quarry on Church Hill, where the fossil star-fishes were once so abundantly found, has been either worked out, or excavation has been discontinued. In the larger quarry at Mocktree Hill, not far off, we again come upon tracts of this Silurian star-fish bed. Mr. Marston, of Ludlow, has a splendid series of these fossils, among them Protaster Marstoni ; and in the Ludlow Museum the visitor may see slabs on which more than a score of fossil star-fish are crowded FOSSIL STAR-FISHES AND SEA-URCHINS. 139 in picturesque confusion. Shepherd's Quarry, near Ludlow, is another good hunting-ground. In some respects, one species, perhaps the most beautiful of the entire group, named after Professor Sedgwick (P. Sedgwickii\ is allied to the "feather-stars" (or rather to that division represented by Euryale), on account of the peculiar spines on the plates of its arms. This species is found only in the older rocks, Fig. 1 16. Upper Siluiian Star-fishes (Ludlow rocks): i and 2. Protaster Miltoni ; 2 a, small portion of arm magnified, showing plates; 3, Palceocoma Marstoni; 4, PalcEocoma Colvini. (From Symond's " Records of the Rocks.") such as the Caradoc beds at Bala, on the west side of the beautiful lake, and at Underbarrow, in Westmore- land. At Benson's Knot, Docker Park, and other places near Kendal, in Westmoreland, where the upper Ludlow rocks crop out and quarries are opened in them, a student may expect to find Palceasterina primceva, and Uraster Ruthveni, the latter named after one of the most diligent and devoted of amateur 140 OUR COMMON BRITISH FOSSILS. geologists that ever lived. Both the latter fossils belong to the same group as our modern "five- fingers," and they have been beautifully preserved (as any one may see, who pays a visit to the Kendal Museum), in spite of the skin being only thickened with calcareous spicules, and not plated. Two species of fossil star-fishes have been found rather plentifully in the Cambrian rocks at Welshpool, Meifod, and Corwen. The Silurian beds in a quarry at Rumney, about two miles from Cardiff, have yielded Palceaster. Dr. Ricketts has found Protaster Salteri on the east side of Bala lake ; and the same species has also been met with near Llangower. Mr. W. J. Harrison be- lieves there is a Rhaetic stratum which deserves the name of a "star-fish bed." This bed occurs in the Spinney Hills, near Leicester, as a thin, sandy layer about half an inch in thickness, completely made up of the joints of star-fish. The Rhaetic black shales at Garden Cliff, Westbury, Gloucestershire, have also yielded star-fish ; and Mr. T. Stock has found remains of them in the same strata at Aust Cliff, on the Severn. Mr. Harrison further shows that remains of fossil star-fishes (probably Ophiolepis Damesii] occur in the famous richly fossiliferous Rhaetic section which stretches along the coast from Penarth to Lavernock. Remains of star-fish from this place may be seen in Cardiff Museum. Next we come to the Lias strata for star-fishes, and we have already seen that one bed is especially rich in them. The FOSSIL STAR-FISHES AND SEA-URCHINS. 141 Liassic species usually belong to the "brittle-stars," and the commonest of these fossils is Ophiolepis Eger- toni, found at Staithe, near Whitby ; and also abun- dantly in various places in Dorsetshire, especially at Seaborne. Specimens of this star-fish may be seen in nearly every museum in England. Pretty little specimens of Ophiolepis are found in the Lower Lias of Burton Passage, near Berkeley, in Gloucestershire. A well-known fossil Oolite star- fish is Ophioderma Egertoni, abundant in the "star- fish bed" at Down Cliffs, between Charmouth and Bridport Harbour, in Dorsetshire. Astropecten is, perhaps, the most beautiful of the fossil star-fishes found in the Oolite, and fine specimens may be seen in the museums at York and Scarborough. The neighbourhood of the latter place has yielded them in some numbers, and the young geologist may pos- sibly be delighted by securing one for his own cabinet if he patiently goes on splitting the large nodules which fall out of the calcareous grit under Filey Cliff (near Filey Brig). Astropecten is also found in the Stonesfield Slate at Eyeford, Gloucestershire. Ophio- coma occurs in the calc grit beneath the Kimmeridge Clay, between Soundsfoot Castle, near Weymouth, and the Portland Ferry bridge. The Upper Green- sand at Blackdown, Devonshire, yields several fossil star-fishes. The marginal plates or ossicles of star-fishes allied to the cushion-stars (Goniaster) are not uncommon 142 OUR COMMON BRITISH FOSSILS. in the Chalk, and in the flints which come from that deposit. In the Chalk quarries at Gravesend, Charlton, many places in Kent and Sussex, as well as Norfolk (particularly about Norwich), remains of these Echino- derms may be found. I have seen perfect specimens imbedded in the flint nodules obtained from Ipswich and Norwich. All the Cretaceous star-fishes belong to Fig. 117. Fossil Star-fish from the Rhaetic beds (Oj>hio?ej>is Dameszt), lower side. existing genera, such as Stellaster, Goniaster, Orcaster, etc. In the London Clay of the Isle of Sheppey we find similar remains of Goniasters ; ossicles, plates, etc., in a more or less perfectly preserved condition. We have already seen that, to a great extent, Encrinites occupy the place in the rocks of the Palaeozoic epoch subsequently held by Sea-urchins and their allies in the Secondary strata, and in the FOSSIL STAR-FISHES AND SEA-URCHINS. 143 seas of the present day. The Sea-urchins are more abundant now than at any previous period in the world's history. They inhabit every sea, and almost every depth in the seas. More than at any other time, one modern group of them (the Echinoidea} now merits the name of Echinodermata, or " Spiny-skinned," given to the entire order. The common Sea-urchins, Fig. 118. Upper side of ditto. such as Echinus esculenta or E. miliaris, are covered with what are not inaptly called "spines." The Echinoidea are doubly important, on ac- count of their numerical abundance and wide dis- tribution in the seas of the present day, and their great geological antiquity. Their general persistence in the rocks of every geological epoch from the Silurian up to our own is remarkable, and we find I 4 4 OUR COMMON BRITISH FOSSILS. their species and types increasing in number in pro- portion as we approach the present epoch. The common sea-urchin (Echinus miliaris] is a familiar example. It well deserves its name, for, when alive, it is so thickly covered with spines as to greatly resemble the common hedgehog ; when dead, these spines peel off, and the surface is then seen covered with minute knobs or tubercles, to each of which a movable spine was attached, on the principle of the ball-and-socket joint. The shell is composed of car- bonate of lime, and is made up of an innumerable number of separate pieces, all of which are mosaicked together. No fewer than six hundred of these go to make up the entire " test," as the shell is technically called. And yet, although in the adult state it may be several inches in diameter, the shell has not been moulted since the animal was small. The membrane lining the exterior of the test or shell secretes the carbonate of lime diffused through the sea-water. As the membrane is inserted between every one of the six hundred and more plates, it is able to add lime along the edges of each, and thus the whole structure grows out uniformly and symmetrically, almost like the expanding of a bubble when blown out. A more beautiful architectural contrivance could not be imagined than is thus furnished by this insignificant creature ! Take one of the rounded tests we may pick up at the seaside, out of which the animal has been FOSSIL STAR-FISHES AND SEA-URCHINS. 145 removed, and hold it up so that the light is seen through it. Besides the large apertures at the top and the bottom (anus and mouth), you perceive rows of minute punctures radiating, from the summit to the base. These punctures are called " ambulacral pores," and the plates (of which there are five rows) in which the pores occur are termed "ambulacral plates," for a reason that will shortly be seen. In addition to these, there is a plate specially perforated, Fig. 119. Echinus esculenta. On left-hand side is a fragment of test denuded of spines, and showing how the plates are mosaicked. called the " madreporiform tubercle " (for it is porous and spongy, like the common Madrepore coral), and its office seems to be to admit the sea- water as through a filter. From this a sort of canal proceeds internally to a tube which surrounds the gullet at the base of the shell or test like a ring. From this circular canal there radiate, like the arms of a star-fish, certain other canals which pass in front of the rows of per- forated plates, and meet together at the top. Each L 146 OUR COMMON BRITISH FOSSILS. of these five canals gives off in its course innumerable tubes, which protrude through the little punctures and lengthen at the will of the animal. At the base of each little water-tube is a little water-bag, and when this is compressed (as a boy squeezes a hollow indiarubber ball he has filled with water) the minute water-tubes, or " ambulacral feet," are lengthened even be- yond the spines of the animal. Myriads of them can thus be protruded whenever the sea-urchin thinks fit, and they may then be seen wriggling and moving about like f ig. 120. Test or shell of Cidaris coronata, showing the tubercles to which the bases S O many WOrmS, aS WC of spines are attached (Oolitic formation). J saw was the case with a turned-over star-fish. At the tip of each is a sucker, and thus, when a few scores of the " ambulacra " are thrust forth, and have attached themselves to any object, they are enabled to warp the entire shell along, It is in this way, in fact, that most of the true Echi- nodermata crawl along the bottom of the sea. The reverent reader cannot fail to be struck with such a beautiful piece of construction, and a hint might here be furnished to our hydraulic engineers. That this principle has been in vogue for myriads of years is evident by the similar construction of the ancient Sea- FOSSIL STAR-FISHES AND SEA-URCHINS. 147 urchins. Thus in the "fairy loaves," as they are called in the Eastern counties, where they literally abound (the chalk fossils known to geologists as Ananchytes ovata), we see five similar rows of perfora- tions ; and even the somewhat differently fashioned tests of the earliest genus of sea-urchins (Palceechinus), dating from Carboniferous if not from Silurian times, have perforated ambulacral plates, showing that these very ancient animals were then in possession of the hydraulic principle which has been of such inestimable value to their race. The Ananchytes of the Chalk, however, have very small tubercles, and the spines formerly attached to them must have been very small and bristle-like, as is now the case with those of the living Cake-urchin (Bryssus lyrifer), not uncommon in the muddy bottoms of the Kyles of Bute, the Spatan- gus, Amphidotus, and many others. This is not the case with the Cidarids found fossilized in the Chalk with them. The very large knobs or tubercles on the tests of the latter animals (which are especially abundant in tropical seas at the present time) give support to large spines, of a club-shape generally, and often ornamented by various devices. Their ball- and-socket principle of jointing, however, was in use in, and has been ever since, the geological epoch termed the Silurian, when the Echini were probably first introduced. In the Oolitic strata we meet with some of the handsomest specimens of Cidarids, and it is very peculiar that, like the fossil Oolitic corals, 148 OUR COMMON BRITISH FOSSILS. the fossil Cidaridce resemble species now living in tropical and subtropical seas. The "cake-urchins," of which our recent British species of Spatangus is a well-known example, date from the Cretaceous, or Chalk period ; and the fossils are so common as to have obtained the popular name of " hearts " in chalk districts. In number of species, however, and variety of external form, these Echinoidea are most abundant in Tertiary strata. It is a peculiar law in the history of a race of organic beings, that they have a period of introduction ; one when they reach their maximum, both numerically and in variety of species ; and another when these drop off one by one, and the race becomes extinct. We then find that the functions they performed are taken up by some other kindred group of animals, which, as a rule, is more highly endowed and specialized, and so its members have been able to thrust aside and extinguish their older comrades ; just as British weeds are now supplanting the native plants of New Zealand and elsewhere. The nervous system in a modern sea-urchin is arranged round the mouth, which is furnished with five hard calcareous teeth, to enable it to triturate its food. These teeth are worked by muscles, through loops, and the whole can be removed as easily as an artificial set of teeth. In this state the mechanism goes by the name of " Aristotle's lantern," and the seaside picker- up of " unconsidered trifles " frequently finds it lying by itself after the more fragile test has been broken to FOSSIL STAR-FISHES AND SEA-URCHINS. 149 pieces. I have seen silicified specimens of Echini in Chalk flints near Norwich which have had these teeth fossilized, but such examples are exceedingly rare. Nevertheless, it affords another instance of the persistency of a plan. Generally speaking, the larger number of the Echinoidea of the Chalk seas had the mouth and anal aperture at the base ; and such genera as Ananchytes, Holaster, Micraster, Galerites, etc., are grouped according to the position of these apertures, which is always constant in the same Fig. 121. Cidaris coronata, showing mode of attachment of the club-shaped spines. species. In the recent Echinus, as well as in the fossil Cidarids, the mouth is at the base and the anal orifice at the summit. The modern Bryssus (as I have already noted) buries itself in very fine mud, on the organic matter of which it appears to feed, just as earthworms do on the black soils. The Micrasters and Spatangi of the Cretaceous period, which approach the Bryssus very nearly, both in shape and structure, may have ISO OUR COMMON BRITISH FOSSILS. buried themselves in the chalky mud of the ancient sea in a similar manner. Some of the modern Echini, on the other hand, have the power of hollowing for themselves holes in the rocks by the sea, especially in Fig. 122. Ananchytes ovata, or "fairy loaf," a common Cretaceous Echinoderm: a, base, showing position of mouth and anus. limestone rocks, which are not unfrequently found riddled by them, just as they are by Pholas and other Fig. 123. Natural flint cast of interior of AnancJiyte (very common in Norfolk and Suffolk), showing the perforations (in relief) for ambulacral or sucking-feet. boring molluscs. A pretty little sea-urchin, not quite so big as a threepenny piece, which we find not uncommonly fossilized in the Red Crag beds, is the DOSSIL STAR-FISHES AND SEA- URCHINS. 151 Echinocyamus. In some respects it is a connecting link between the Echini, or sea-urchins, and the "heart-urchins," or Spatangi. The common "sea- egg " (as fishermen call it), or Echinus sphczra, is as old as the Pliocene period, for I found it in the Coralline Crag beds. The common " sea-egg," how- ever, is not the type with which we ought to compare the very abundant " fairy-loaves " (Ananchytes) found so plentifully in the chalk. The mouth and anus of Ananchytes are both at the base, whereas in the sea- Fig. 1-24,Micraster, a common Cre- taceous Echinoderm, showing the "petaloid" arrangement of the ambulacral areas. Fig. 125. Galerites albogalerus, a common Cretaceous Echinoderm. egg they are relatively at the base and the summit. In the Ananchytidce must be included the extinct genera, more or less common in the Chalk, of Holaster, Galerites, etc., in which the basal position of mouth and anus is slightly different. Indeed, the genus Ananchytes appear to be entirely confined to the Cretaceous strata. The nearest living type of sea- urchin, allied to the Ananchytes, or " fairy-loaves," was dredged up in the North Atlantic during the Challenger expedition, from a depth of nearly 152 OUR COMMON BRITISH FOSSILS. three miles, and it is known by the name of Calymne relicta. The bottom of the Atlantic is remarkable for a number of creatures living there which are allied to those found in the fossil state in the Chalk formation. The family of sea-urchins called Pourtalesia is of this character, for it is allied to the extinct Ananchytes in many respects. But perhaps the most remarkable living Atlantic sea-urchin is Salenia varispina, dredged off Cape St. Vincent at a depth of nearly two miles. A few years ago this genus was believed to have been extinct for ages, for it was not found outside the Fig. 126. Echinus gramilosits. Fig. 127. Salenia personata. Chalk, unless we except the Acrosalenia of the London Clay, at Sheppey. Now it has turned up in the living state in the Atlantic. Salenia is common in the Chalk near Norwich, and internal flint casts are also found there so abundantly that they go by the name of " pick-cheeses " " pick-cheese " being the name given to the ripened seed-vessels of the common mallow, which the flint casts of Salenia very closely resemble. Internal flint casts of Ananchytes, or "fairy-loaves," are abundant wherever the Upper Chalk crops out, and they are often remarkable for FOSSIL STAR-FISIfES AND SEA-URCHINS. 153 possessing the clearest and most distinct relics, in relief, of the ambulacral pores. Salenia are especially numerous and well preserved in the Greensand beds in the neighbourhood of Warminster, in Wiltshire one of the pleasantest spots for geologizing that the student could desire. Among the principal common fossil sea-urchins found in the Upper Greensand there, and at Chute Farm, are Discoidea subulata, Epiaster (a genus allied to Micraster), Catopygus, Pyrina, etc. The Lower Greensand beds are frequently rich in Echinoderms. Thus at Shanklin, in the Isle of Wight, we have a very rich " urchin " bed, containing many singular forms, such as Clypeopygus, Enallaster, and Echinospa- tagzis. The last-mentioned fossil is very abundant in the Upper Greensand of Blackdown, Devonshire, where also many other species of the same kind of fossils are obtained. Holaster suborbicularis and H. sub-globosus are very abundant in a bed between the Chalk Marl and Upper Greensand at Abinger, in Surrey ; also at Lewes, in a similar stratum. Hemiaster is a charac- teristic fossil in Grey chalk about Folkestone, at Hamsey, in Sussex, and Ventnor. The commonest Gault echinoderm found at Folkestone is Hemiaster BailyL The Red Chalk at Speeton contains Discoidea, Holaster, Diadema, and spines of Cidarids. In the oldest known type of sea-urchin (Pales- echinus) the test or shell was composed of more than twenty rows of plates, and the entire test was 154 OUR COMMON BRITISH FOSSILS. of a remarkable egg-like, shape. Archceocidaris is the oldest known Cidaris, or knobbed sea-urchin, and it occurs in the Devonian rocks ; but one species (A. Urii) is not uncommon in the Carboniferous lime- stone of the Derbyshire Peak district, and I have found its spines somewhat plentifully m the queer little limestone quarry at Hafod, near Corwen, in North Wales. Palceechinus seems to occur most plentifully in the Carboniferous limestone of Ireland. Some beds of the Inferior Oolite literally swarm with fossil Cidarids and Cake-urchins. The slabs of Oolitic limestone found in the quarries about Calne may be seen containing a dozen Cidarids, many of them with their spines still attached, just as when they were alive. Leckhampton Hill, near Cheltenham (from the summit of which the tourist can obtain a magnificent view of the Severn valley), is composed of rocks belonging to this formation in which Hypoclypeus agaricifonne is abundant, as well as various species of Cidaris. Hartwell, in Buckinghamshire, is another good hunting-ground for fossil echinoderms. Clypeus sinuata is a fine, large, well-known fossil, well dis- tributed in the Lower Oolitic rocks ; it is, perhaps, most abundant in Wiltshire. The Cotswold Hills have numerous outcrops where quarries are opened in their Oolitic rocks, in which Nucleolites, Cidaris, and Hemicidaris are frequently very abundant. Speaking of the fossil Echini of Calne, Dr. Wright says he has seen slabs from the beds of Coralline FOSSIL STAR-FISHES AND SEA-URCHINS. 155 Oolite at Calne in which were embedded as many as fifty specimens of Echinobryssus scutatus. Clypeus Plotti is so plentiful in the more central parts of the Cotswolds, especially near Naunton Inn, that cart- loads of it may be collected. One of the most beautiful of all the Oolitic Cidarids is Acrosalenia hemicidaroides, frequently found, with all its spines still attached to the body, at Chippenham an excel- lent fossilizing locality in company with another pretty species, A. spinosa. Rushden in Northampton- shire, Malton in Yorkshire, Charlcombe near Bath, Malmesbury, Minchinhampton, Sudely Hills, Glouces- tershire (where Pygaster semisulcatus is found three and a half inches in diameter), Crickley, and Carn- long (Devon), are all good localities for fossil Oolitic Echinoderms. These fossil Cidarids are very beautiful objects when denuded of their thick, club-shaped spines (Fig. 120); the test is seen ornamented with and composed of a series of polygonal plates, each with a large round tubercle in its centre, and a pearl- like setting of a ring of smaller ones around it. Even the club-like spines are frequently beautifully sculp- tured, and the student can plainly see in their hollow bases how they were attached to the round tubercles, after the mechanical fashion known as a " ball-and socket joint." The quarries at Calne and Chippen- ham, in Wiltshire, are especially famous for their abundant yield of fossil Cidarids. Echinobryssus and Clypeus are fairly common in the rocks of Constitution 156 OUR COMMON BRITISH FOSSILS. Hill, Banbury, unless the pits are now filled in. The Oolitic rocks which crop up from Grimston to Bur- dale, near Scarborough, contain beds full of Echino- bryssus scutatus^ besides spines of Hemicidaris. Various species of Cidardis are also found in the Kentish and Norfolk Chalk, either whole or as detached plates ; and sometimes we find the impression of one of the latter on a flint, when it presents a very pretty appearance. Solitary club-shaped spines and impres- sions of the same in flint are very common in the Chalk formation generally. In the Greensand at Warminster, which crops out from under the escarp- ment of the Downs, the geological student may find a good assortment of fossil Echinoderms, such as Nucleolites, Caratomus, Cidaris pusio, Goniophorus favosus and G. lumdatus, Holaster granulosus, Micr aster lacunosus, Salenia clathrata, S. geometrica, S. ornata, S. umbrella, etc. Faringdon, in Berkshire, is another rich Greensand formation abounding in fossil Cidarids, where Salenia petalifera is especially plentiful. Charlton, near Woolwich, is a good place for Chalk Cidarids ; and the well-worked pit near the railway station will afford the student good specimens of many other Cretaceous fossils besides ; whilst the Tertiary sands overlying the Chalk sections are in places rich in peculiar fossils. Very fine Cidarids may be obtained from the Chalk quarries at Grays, Essex. The Chalk near Caterham yields Holaster and others. The Chalk quarries near Hitchin station are very rich in Holaster globosa, etc. FOSSIL STAR-FISHES AND SEA- URCHINS. 157 The rambler can hardly go into the wrong quarry in the Upper Chalk for Ananchytes, Micraster, Gale- rites, etc. They are especially numerous in the large Chalk-pits which nearly surround the city of Norwich. The white-surfaced Chalk-flints, which lie in heaps in the quarries ready for breaking up into road metal, should be carefully examined if possible one by one. I have found many " fairy-loaves " and their kind half-imbedded in these hard flints, plainly showing that the latter must have been soft when the fossils were thus buried. In the Chalk-pits about Guildford may be collected Holaster planus, Micraster cor- brevis, M. testudinaritim, etc. Cidarids are abundant in the Chalk at Gravesend and Dorking. The com- monest of these in this formation is Cidaris clavigera. Another common fossil of this kind is Cyphosoma corollare, abundant at Brighton, Gravesend, and Woolwich. Cardiaster (allied to Holaster) is found at Maidstone. Many of these Chalk-pits are in lonely localities just the very places a man would select for quiet walks, or for attractive scenery ; and indeed, the tourist finds that the fossiliferous rocks usually crop out where Nature is apparelled in her most attractive garb. 158 OUR COMMON BRITISH FOSSILS. CHAPTER VI. FOSSIL WORMS (ANNELIDA). DARWIN recently showed how geologically important is the common earth-worm. A biologist as intimately acquainted with the life-histories of other insignificant creatures would be able to prove that the most insig- nificant of them plays some part or other in geological operations. They may not be Founders of continents, like the Foraminifera and the Corals ; but the world would have been different in some way or another if they had not existed. A Worm is the lowest member of a sub-kingdom of animals on which perhaps more changes have been rung than any other. It is an annulose, or ringed animal. It forms the fundamental structure which may be modified according to circumstances, into a lobster, crab, scorpion, spider, butterfly, beetle, bee, dragon-fly, cockroach, or house-fly ; besides other crea- tures which crawl, fly, and swim. Throughout life it may retain the primitive structure we are acquainted with in the common earth-worm or lob-worm ; or FOSSIL WORMS. 159 this may be but the first stage in a series of sub- sequent improvements and modifications, as in the grub-like larvae of the bee and beetle, or the cater- pillars of the moth and butterfly. Just as the worm or annelid type is largely a fundamental one, so is it one of the most ancient, geologically speaking. In rocks, where traces of neither mollusc nor zoophyte are visible, tracks of ancient sea-worms have long been known. No other creature can claim such a geological immortality. Not even the foraminifera arc such eloquent or trustworthy witnesses of the slowness with which certain deposits were laid down than they. In all marine forma- tions, from the Cambrian to the latest Tertiary, sea- worms have left abundant proofs of their existence. Many of the so-called " worm or annelid tracks " in Silurian rocks, such as those denominated Chon- drites or Cruziana, may have been left by creeping mollusca or crawling Crustacea. But in the absence of the solid parts of these creatures in the fossil state, it is safer to assign such tracks to worms. In deposits where fossil univalves and crustaceans are actually met with, such tracks may have been left by them. Still, the careful student cannot but be aware, from his quiet study of any low-water mud or sand-flat at the present day, that for one track left of Crustacea or mollusca, ten are left by sea-worms. In short, they are the great track-makers, as well as sand-diggers ; and we may safely give them this position without i6o OUR COMMON BRITISH FOSSILS. minimizing the importance of the markings left by other animals. If subsidence of certain parts of the sea-floor were not accepted as a geological and geographical fact, sea-worms would prove it more than any other animals. For when we find such rocks as the Long- mynds, composed of strata all more or less of a similar physical character and composition, on whose upper surfaces are innumerable tracks of sea-worms for at least one mile in vertical thickness, no other theory could account for the conditions under which they had been formed than that which declares the sea-bed was slowly subsiding, at about the same rate that the sediments were accumulating. Moreover, the same worm-tracks more or less indicate the depth at which such deposits were formed, for we never find these markings in strata of deep-sea origin ; and the supplementary evidence of the ripple-marks so fre- quently occurring in worm-tracked strata, is confirma- tory on this point. Geology has little or nothing to say concerning terrestrial worms, unless it refers to their physical action in modern times. I am not aware of a single species which can be safely referred to the same habitats as our common earth-worms, although I have little doubt this class has been in existence, perhaps during the entire Tertiary period, if not longer. I have therefore only to do with sea- worms. These, as we now know them, may be FOSSIL WORMS. 161 divided into two groups, those which crawl or swim about (as the lob-worms and the Errantia generally), M 162 OUR COMMON BRITISH FOSSILS. and those which adopt a fixed existence. The former have no hard parts to leave behind them when they die, except their horny jaws, and these have been found by Dr. Hinde in considerable quantities in the Silurian and other rocks. Until a few years ago we were entirely indebted for proofs of the former exist- ence of this class of sea-worms to the tracks they left behind them on primaeval mud-flats, and the discovery of their jaws is additional evidence in favour Fig. 129. Horny Jaws of modern marine Annelida. of these tracks being of annelid origin. The other class of sea-worms, adopting a settled marine life, live in tubes, which are formed of grains of sand, etc., cemented together, as in the instance of our modern Terebella ; or they may be leathery, as in the recent Sabella; or their outer skin may secrete lime, and thus form a solid tube, as illustrated by the empty tubes we see attached to old oyster-shells, stones, and rocks. In both the latter cases the breathing organs are gathered into one place, and form a beautiful feathery tuft, sometimes brightly coloured, as in those of that little coiled worm which rejoices in such a high antiquity, the Spirorbis. FOSSIL WORMS. 163 Let us take the wandering worms (Errantia) first in order, as they probably were first in point of appearance in the earlier seas of our globe. The names assigned to the com- monest of the tracks and trails believed to have been left by them are borrowed in most in- stances from modern genera ; thus we have Phyllodocites, Myrianites, Crossopodia, A renicolites, etc. The markings we have to explain are of two kinds, burrows and trails. The sea-worms making the former were doubtless of similar habits to our common lob-worm {A renicolapis- catorum} and the generic name of Arenicolites at once indicates this. The Cambrian rocks of Bray Head, near Dublin, have long been famous for the occurrence of markings left by an ancient burrowing worm, named by Dr. Kinahan Histioderma Hibernicum, associated with the zoophyte Oldkamia. The tubular casts of these worm-holes may be obtained. The upper part swells Fig. 130. Coriaceous tube of Sabella unispira (recent). i6 4 OUR COMMON BRITISH FOSSILS. out into a trumpet-shaped mouth, frequently very prettily marked. The holes of Arenicolites sparsus and Arenicolites didymus are in pairs, and are found in the same beds as Histioderma. Fig. 131. Tentaciilites anmilatus (a supposed Silurian Annelid with calcareous tube). The flag-stones obtained from the Millstone grit formation in Lancashire and Yorkshire have their surfaces frequently knobbed irregularly with the casts of worm-furrows. Young geologists who often sigh FOSSIL WORMS. 165 for opportunities to geologize abroad should keep their eyes open to the periodical mending of the roads and causeways of the towns in which they live. In the neighbourhood of Manchester and Sheffield the Fig. 132. Tracks and Burrows of Arenicolites sparsus, with Oldhamiet. newly laid flags are often seen ripple-marked, and worm-tracked or worm-burrowed. The Cambrian and Silurian sandstones afford similar evidence of shallow water deposition. In the Stiper Stones (Upper Cam- brian) both casts and burrows are abundant. In the Bangor slate quarries the markings are called CkondriteS) from the origi- nal belief that they were impressions left by seaweeds, but I favour the theory of their annelid origin. In the slate quarries Fig. 133. Burrows of Arenicolitet didymits. 166 OUR COMMON BRITISH FOSSILS. near Douglas, in the Isle of Man, there may be frequently found the tracks of two kinds of sea- worms, Nereis and Nemertites. As before remarked, however, the Longmynd rocks afford by far the largest number of evidences of ancient sea-worms. In the Wrekin the quartzite beds yield Arenicolites Urico- niensis, which may be considered the oldest known British fossil. The rocks of St. David's contain both Arenicolites and Serpulites. In the Skiddaw slates, Fig. 134. Burrow of Histioderma Hibernicwn. near Keswick, Cumberland, ten species of the remains of fossil-worms have been catalogued, among which Scolithus and Helmintholitkus are the most abundant. One remarkable species has been named Stellascolites. In many parts of Great Britain the lower Carboni- ferous rocks possess most abundant traces of worm- tracks. Any tourist who has visited the magnificent Cliffs of Mohr, in county Clare, Ireland, cannot fail to have noticed the dark slaty flags of the district, FOSSIL WORMS. 167 marked all over, below and above, with sinuous worm-tracks. These cliffs rise sheer out of the green Atlantic to a height of three hundred feet, and appear to be of the same character throughout. Everywhere, where it is possible to examine them, the thin flags are crowded with these peculiar markings. People who have been to the celebrated quarries in the same geological formation near Kirkby-Lonsdale, will have observed the flags impressed in a similar way. I give a sketch of them as they appear in a hand specimen. As these Kirkby- Lonsdale flags are much in demand by house-builders in the north, and therefore get widely distributed, some of my readers may have seen them a long way from their parent quarry. The commonest of these worm- markings is Crossopodia. In Pen- whapple Glen, Girvan, Ayrshire, many species of worm-tracks have been recognized, belonging to Nereites, Myrianites, Crossopodia, Nemertites, etc. ; annelid markings are also found in the shales at Moffat. A peculiar / kind of worm-track, called Cyma- Fig I3S ._ Large 'tubular derma, is left on the surfaces of the gg^S**""" i68 OUR COMMON BRITISH FOSSILS. Lower Carboniferous rocks near Settle, in the Valley of the Kibble. No doubt most, if not all, of these tracks were made by worms like our common Nereis. This had long been suspected before Dr. Hinde, by dint of great patience, discovered annelid jaws in the Silurian shales at Ludlow, Much Wenlock, Iron Bridge, Stoke Edith, and elsewhere. These are figured in his paper on the subject read before the Geological Society. ^The largest of the annelid jaws he found so plentifully did not exceed one-fifth of an inch. Dr. Hinde has proved that these jaws differed as much among themselves so far back as the Silurian period as they do now a plain indication of the antiquity of the tribe. Worms which form tubes cannot of course make tracks, but they leave evidences of their existence behind them in the fossil tubes they once inhabited. These sometimes form strata of no inconsiderable thick- Fig. 136. Extremity of Tube of Histioderma. Hibernicum. Fig. T.n.Serpula. with tentacles expanded (recent). FOSSIL WORMS. 169 ness. Indeed, any geological student who has visited the seashore of St. Bee's, Cumberland, at low water, will have noticed extensive beds formed solely of the cemented sand-tubes of modern species of Sabellaria. Sabellaria and Terebella are very common tubed worms in British seas, both of them constructing sand-cemented tubes. The latter is always abundant where there is a hard, clayey sea-bottom. It is rarely Fig. 138. Nereis (recent). that we get these worm-tubes fossilized, as they tend to fall into their component grains of sand when the worms die. With the hard, calcareous tubes of such species of sea-worms as Serpula and its kind, we have no difficulty. This form of Annelid has had, perhaps, a more stereotyped or stable form of existence than any other creature in the world. There is no osten- 170 OUR COMMON BRITISH FOSSILS. sible difference between many Silurian-tubed worms and those now in existence. The pretty little Spirorbis found in the Upper Silurian rocks has had a continuous and unchanged existence through every geological period until now. We find it attached to fossil shells and corals in the Silurian and Devonian limestones. Fourteen species occur in the Carboni- ferous rocks, some of them found adhering to the trunks of Sigillaria and almost encrusting them, just as we find them adhering to the larger seaweeds along our shores. Under the names of Serpulites^ Cornulites, Tentaculites, Conckiolites, etc., the sea of every geological period has abounded in tubed worms. The Wenlock limestone literally swarms with these tapering elegant tubes, ringed like the tentacles of insects, and hence called Tentaculites. This is a type of what is called a. free worm-tube, i.e. one that is not attached to shells or rocks, like the modern Serpula. By some geologists it is still regarded as a pteropod mollusc allied to Hyale. Cormilites is another genus nearly related to it, and both are characteristic of the Silurian formation. The chief species in the latter rocks is Cornulites serpularius. It is frequently found as much as three to four inches in length, ringed, and gradually tapering to a point. Casts of this species of worm-tube frequently occur, and the young student might be easily misled by them into thinking it was a different fossil to the Cornulites found with its external shape ; for this internal cast is in a series FOSSIL WORMS. ^ 171 of sharply marked off segments, one within but less than another, like the fully drawn-out parts of an old-fashioned telescope. This species is very abun- dant in the Woolhope beds. Ortonia (named after Professor Orton) is a genus of abundant annelid tubes, also free, which is peculiar to the Upper Silurian rocks of North America. Tentaculites annu- latus is the commonest of our British species ; T. ornatus being perhaps the prettiest. The former is more abundant in the Lower Silurian rocks at May Hill and elsewhere, and the latter in the Upper. The Wenlock shales are very rich in fossil worms, Mr. Etheridge recording no fewer than thirty-five species of all kinds, Dr. Hinde having added twenty- four. Among the characteristic forms of these beds are Trachy 'derma and Aranellites. No doubt there were ancient sea-worms resembling Serpula, and it is possible some may have been inter- mediate between it and the modern Sabella, which latter is possessed of a leathery tube, often strength- ened by adhering sand-grains. Thus, in the Upper Silurian rocks above Ludlow, we meet with numerous traces of a thin calcareous worm-tube, transversely striated, and very ribbon-like, called Serpulites longissimus. Trachyderma coriacea is still more like a Sabella tube stiffened by a deposit of lime. Scolio- derma serpulites is found in the rocks of the Wrekin and in the holly-bush sandstones near Malvern. Serpulites dispar is abundant about Ludlow, and also 172 OUR COMMON BRITISH FOSSILS. in the Upper Silurian rocks near Kendal ; and the student will find a capital collection of them in the museum of that town. A more delightful neighbour- hood for fossilizing than Kendal can hardly be found in England, or a more varied one. I have seen Serpulites more than a foot long in the deserted Silurian quarries near Ledbury. The Secondary rocks contain true Serpula, and these fossils are not without a special value to the physical geologist. Some of them may be found sprawling over the interiors of bivalve shells, or covering the naked tests of sea-urchins in both instances plainly informing us that the life-and-death conditions of the ancient sea-floors were very like those of our day. Moreover, the occurrence of these creeping worm-tubes over the dead tests of such sea- urchins as Ananchytes one of the commonest in the Chalk shows us that the chalky ooze must have been forming very slowly, or it would have buried up the dead animals before the sea-worms had managed to spread their tubes over and about them ! We frequently get the tubes of Serpula attached to fossil bivalves in the Lias and Oolitic rocks : some- times they form dense and tortuous masses, as in the Oolitic marlstone near Banbury, and in the well- known " Serpula-bed " at Blue Wyke Scar, near Scarborough where the geologist may obtain abun- dant fossils, and enjoy some of the finest coast scenery in England at the same time. The tabular Iron- FOSSIL WORMS. 173 stone of the Gault of Kent is frequently full of annelid borings. A hard band of clay in the Gault at Folke- stone, and near Charing, in the same county, is occupied with serpula tubes, which form a thin stratum two inches thick. Serpula plexus is always common in the Chalk ; and near Norwich and Margate it frequently occurs in masses, or completely investing the larger fossil shells, such as Inoceramus. In the Eocene beds the commonest fossil worm- tubes are those of Ditrupa, which was evidently free or unattached to objects, after the manner of the Tentaculites, etc., already described. It is usually found in large numbers, and appears to have been gregarious in its habits. We may get a large quantity of this fossil worm in the London Clay beds of Bognor, Hampshire. Ditrupa plana is the name of the common species. Ditrupa is also found in the crag beds of Suffolk, where it may have been redeposited there from denuded Eocene strata. 174 OUR COMMON BRITISH FOSSILS. CHATTER VII. TRILOBITES AND OTHER FOSSIL CRUSTACEA. To a young and enthusiastic geologist there is no class of fossils to which so much interest is attached as the Trilobites. They are extremely elegant objects, and are easily identified. Their strict limit to the primary rocks makes them geologically valuable as means of identifying strata. Even non-geologists remember their glib, half-scientific, half-popular family name, and will occasionally air it as if it were the complete key to palaeontology. A good collection of well-arranged trilobites looks better in the cabinet than perhaps any other fossils. There is such a variation from the leading type that one cannot wonder the number of genera should be so great. No two are externally alike, and the deviation is sometimes so extreme that the Trilobites are no longer trilobed. Trilobites are among the few fossils which possess the associations of folk-lore. Ammonites and Encri- nite stems, Gryphea and Cycadites, share with them TRILO BITES AND OTHER FOSSIL CRUSTACEA. 175 the feeble notice which the curious gave to them in pre-geological days when all fossils were called "petrifactions," and all were equally regarded as evidence of the universality of the Noachian Deluge. Perhaps nowhere are Trilobites more abundantly visible than in the Wenlock limestones, near Dudley. The latter have been upheaved to a very high angle, and the surfaces of the hard limestone slabs are so thickly bestrewn with fossils, that it is impossible to place the tip of one's finger without its coming into contact with some of them. These limestones are constantly clean, from weathering. They are veritably museums of Upper Silurian fossils, and although hard to extract with the hammer, the student may while away many a summer hour in gloating over these lovely treasures of the ancient deep. Trilobites are there in uncountable thousands, but nearly always in disjointed " heads " and " tails." We cannot wonder, therefore, that they should have attracted the attention of those fond of natural phenomena, although in the days long anterior to scientific explanations of them. As " Dudley Locusts," one genus of Trilobites (Calymene) was long known ; even the fact of their standing out in relief from the limestone was noticed as very remarkable, for nothing was known in those days of sub-aerial denudation or weathering of rocks. They were named "Trilobites" as long ago as 1771, by Walch, in his " Natural History of Petrifactions," 176 OUR COMMON BRITISH FOSSILS. on account of the three lobes of joints which usually run along the body. Still, their crustacean origin had been guessed at by bold speculators, and even Lin- naeus classed them among the Entomostraca. How utterly at sea the majority of naturalists were as to the true nature of these singular fossils is indi- cated by some of their generic names. Agnostus, Asaphus, Calymene, etc., the commonest of these, are only Greek words signifying " unknown," or " con- cealed," etc. Still, since the time of Brongniart they have been universally regarded as crustaceans, and the universal opinion is that they are allied to the Isopoda, only that they were legless. Dr. Henry Woodward, F.R.S., who has taken up Mr. Salter's investigations among the Trilobites with great en- thusiasm, believes he has detected evidences of legs on the under side of some specimens, and his belief has recently been confirmed by the discovery of Trilo- bites with legs in America. Other naturalists think these members are only the remains of "calcic arches." The extinct Trilobites really represent a defunct order, and as such we usually find them arranged in system- atic works on Zoology. In that case they come in as " missing links " between the Isopoda, of which the common woodlouse (Oniscus) and the shrimp-para- site (Bopyrus) are familiar types, and the Merostomata of which the well-known "king-crabs" (Limulus) are examples. The larval state of the higher classes in the same order frequently resembles the adult condi- TRILOBITES AND OTHER FOSSIL CRUSTACEA. 177 tions of the lower. In the Crustacea a very large number of genera are alike in their youngest state. From its resemblance to the adult condition of one of the lowest of the crustaceans called Nauplius, this state is usually called the " Nauplius stage." No other group of animals passes through so many metamor- phoses before reaching maturity, and each of these is so well marked off from the rest, that it might be 139. Asaphus caudatust Fig. 140. "Dudley locust' or Trilobite (Calymene Blutnenbachii). regarded as a generic type. Indeed, in many cases genera have been founded on these distinctions, so that the same animal, at different periods of its life has been regarded not only as a distinct species, but as belonging to another genus. The young of the common lobster, for instance, passes through at least six stages, which are so unlike each other that only careful observation has settled they are not different N OUR COMMON BRITISH FOSSILS. animals. Even when it has reached the adult condi- tion, a lobster is so unlike what it will be when full- grown, that it might be set down as belonging to another genus. It is as if we knew nothing of the metamorphoses of the butterfly, and therefore had mistaken the caterpillar and chrysalis for animals belonging to groups wide separated from the winged insect. The young of the recent Limulus, or king-crab, greatly resembles the adult Trilobites. As the king- V Fig. ^r.Prestwichia. Found in the " Penny-stone " nodules, Fig. 142. Larva Shropshire. of recent King-crab. Fig. 143. Larva of Trilobite. crabs succeeded the latter in geological time, it may be that it was due to the Trilobites having been "advanced a stage." One genus found in the ironstone nodules of Coalbrookdale, called Belinurus, more nearly re- sembles one genus of the Trilobites (Trinucleus) than the king-crabs of our own days. Again, the female Bopyrus (Fig. 149), which parasitically attaches itself to the inner surface of the carapace of the shrimp, has a rude resemblance to the segmented body of some of the less highly organized Trilobites. The fact of its TRILO BITES AND OTHER FOSSIL CRUSTACEA. 179 being a parasite shows that it must have undergone Fig. 144. Under surface of recent King-crab (LttnuZus). retrogradation. The figures will show that the Trilo- i8o OUR COMMON BRITISH FOSSILS. bites find their natural history place between the groups above named. Haeckel, however, places them among the " gill-footed crabs " (Branchiopoda\ of which the water-fleas are familiar examples. He does r ig. 145. Fossil King-crab, from Coal measures of Coalbrookdale (Belinurus trilobitioides] . Fig. 146. Trinucleus fintbria- tus, Upper Llandeilo beds, Builth. not tell us on what grounds this is done, for no breath- ing or locomotive organs have as yet certainly been found, although thousands of specimens of all the genera have been carefully examined on their under Fig. 147. Compound eye of fossil Trilobite (AsapJius caudatus) slightly magnified. Fig. 148. Ocelli of ditto (magnified). sides. Again, the compound eyes of the Trilobites show that they were in this respect really very highly organized, and this highly developed specialization of the sense of sight certainly proves that they ought to TRILOBITES AND OTHER FOSSIL CRUSTACEA. 181 be placed much higher among the Crustacea than we find them in Haeckel's " Systematic Survey." In many species of Trilobites the empty eye-sockets can be seen with the naked eye, notably so in Asaphus caudatus, in which each eye contained four hundred facets. According to Owen, Asaphus tyrannus pos- sessed no fewer than six thousand eyes ! The number of eyes among the Trilobites varies considerably ; some specimens have none at all. I have already referred to the fact that the Tri- lobites are peculiar to the Primary rocks. Although they seem to range as high as the Permian, they are chiefly confined to the strata below and including the Carboniferous limestone. No fewer than four hundred species, grouped in fifty genera, have been described from these formations, and new forms are still occa- sionally met with. The greater number of the species are of a Silurian age ; those of the Devonian rocks are of a well-defined character ; and those from the Carboniferous limestone even more distinct still. It would seem as if they reached their maximum of size, as well as of variation, during the Silurian period. The largest are Asaphus gigas y eighteen inches in length, found at Llandeilo ; and Paradoxides, two feet long. On the other hand, they appear to have decreased in size as well as in numbers when we reach the Carboniferous rocks. The genus Phillipsia, there represented, rarely includes specimens more than three-quarters of an inch in length. It ought to 182 OUR COMMON BRITISH FOSSILS. be stated, however, that we know little about the embryology of the Trilobites. There can hardly be a doubt that many of the so-called species, and even genera, are larval stages in the development of the same species. I have referred to the common lobster Fig. 149. Parasite of Shrimp (Bopyrus crangorutn) ; a, upper side ; , profile ; c, under side ; d, highly magnified and aborted foot ; e, upper side of male Bopyrus, much smaller than female;/] lower side of ditto; g, part of carapace of shrimp, swelling out to show presence of parasite underneath. as an illustration of the clearly marked characters appertaining to the various stages in the life-history of the same individual. Each of these stages is accom- panied by as many " moults ; " and if we reason from our general experience of the embryology of the TR1LO BITES AND OTHER FOSSIL CRUSTACEA. 183 Crustacea, we must allow that the Trilobites were affected in the same manner. The number of larval stages they passed through depends upon the position they attained as regards organization. This was much higher than Haeckel imagines, and therefore the stages may have been numerous. It is to be expected that individuals would die and be buried in the muddy ooze in each of these intermediate states. Thus found, what more natural than to regard them as different species, and even different genera ? Only a fuller knowledge of crustacean embryology will clear away a good deal of the useless nomenclature which has gathered about these interesting creatures, and it is hardly to be expected that we shall ever know their accurate life-history. Barrande, who had such splen- did opportunities for studying the Trilobites, and who made equally good use of them, satisfied himself, in the case of no fewer than twenty different species of Trilobites, that they passed through larval stages, each unlike the other. In some instances he traced them from when they had only just escaped from the egg to the fully developed and mature state. In the first instance they had no joints to the body, and there- fore strongly resembled one of the carapaces of the "water-fleas;" in the last they possessed ring-covered bodies, movable tails, and compound eyes. This proves that, although in their young states Trilobites resembled the Ostracoda, in their adult life they had oroceeded much further. Parallel with the instance i8 4 OUR COMMON BRITISH FOSSILS. of the development of the lobster, all the above changes noted by Barrande in the Trilobites occurred before the animal had attained a tenth part of its full size. In Lyell's " Manual of Geology " the student will find engravings of the Trinucleus in three stages, each of which appears specifically distinct from the other. Another skilled observer of the Trilobites was Burmeister, who believed that all of them underwent metamorphoses. Recently the larva or young of a beautiful and highly developed Trilobite (Conocoryphe) has been found in this country. In the case of fossils less care has been taken than with living animals, and, in many instances, some of those who have christened species were geologists rather than naturalists. The slightest differences have been sufficient to warrant a new specific name, and thus it is more than possible that the various stages in the life-history of one and the same species may be illustrating our manuals as distinct genera and species ! Even with regard to sex in adult individuals, little or nothing is known ; although among nearly all the Crustacea these differ so ex- tremely. Owen remarks that the difference in the head plate and the terminal spines of the tail in the two so-called species named Asaphus caudatus and Asaphus longicaudatus, may only be due to difference of sex ; the inference, therefore, is that these two species represent the male and female of only one. The earliest Trilobites, such as the eyeless Agnostus, are usually the simplest in structure, so that these TRILOB1TES AND OTHER FOSSIL CRUSTACEA. 185 animals are not an exception to the general palaeon- tological rule that the simpler always precede the more complex species of the same genus or class. Nevertheless, this simple and elementary Trilobite is found in company with a more highly developed kind. Agnostus is usually found in large shoals, something after the manner in which the carapaces of the ancient water-fleas are met with in some of the Coal-measure shales. Owen suggests that this disposition of Agnos- tus is "as if it were the larval form of some large Trilobite." The young of all Crustacea usually asso- ciate together in shoals, and this suggestion might therefore be reasonably taken in consideration with what has already been said on the subject. The compound eyes of Trilobites are usually thickly placed on raised half-moon-shaped ridges, and the fact that the sockets are so well preserved speaks plainly of the quiet way in which the fine mud was deposited in which the animals were buried and ultimately fossi- lized. Dr. Buckland spoke of these ridges as being " like a circular bastion, ranging nearly round three- fourths of a circle, each commanding so much of the horizon that where the distinct vision of one eye ceased, that of the other began." He also very saga- ciously referred to the form of the ridges and their position on the head-shield as "peculiarly adapted to the uses of an animal destined to live at the bottom of the water : to look downwards was as much im- possible as it was unnecessary for a creature living at 1 86 OUR COMMON BRITISH FOSSILS. the bottom ; but for horizontal vision in every direction the contrivance is complete." I cannot refrain from further quoting a well-known passage from the same author, in which a logical inference is drawn from the structure of the eyes of Trilobites. "The results arising from these facts are not confined to animal physiology ; they give information also regarding the condition of the ancient sea and the ancient atmo- sphere, and the relations of both these media to light, at that remote period when the earliest marine animals were furnished with instruments of vision in which the minute optical adaptations were the same that impart Fig. 150. Simplest kind of Trilobite (Agnostu the perception of light to crustaceans now living at the bottom of the sea. . . . With regard to the atmosphere, we infer that had it differed materially from its actual condition, it might have so far affected the rays of light that a corresponding difference from the eyes of existing crustaceans would have been found in the organs on which the impressions of such rays were then received. Regarding light itself also, we learn, from the resemblance of these most ancient organiza- tions to existing eyes, that the mutual relations of light to the eye, and of the eye to the light, were the TR1LOBITES AND OTHER FOSSIL CRUSTACEA. 187 same at the time when crustaceans endowed with the faculty of vision were first placed at the bottom of the primeval seas, as at the present moment." That the Trilobites were bottom-feeders and haunters, there can be little doubt. The late Mr. Salter, than whom no geologist was better acquainted with Trilobites, was of opinion that they not only lived there, but fed on the organic mud, something after the manner of earth-worms. The simple struc- ture of their mouths, and the absence of antenncs or feelers, indicate such a habit. My readers will have seen from the illustrations the strong external resemblances between the earliest king-crabs, such as the Belinurus, and one genus of Silurian Trilobites (Trinucleiis}. The chief apparent difference is in the ends of their bodies, that of the king-crab being prolonged into the dart shape which gives to it its generic name, whilst in the Trinucleus it is round. But we have only to glance at figures of various kinds of Trilobites to see that they vary amongst themselves in this respect. Thus in Asaphus cattdatus (Fig. 139), one of the commonest of Lower Silurian Trilobites, we have the pygidium, or tail, drawn into a point. Undoubtedly the Trinucleus (\g. 146) is one of the prettiest of Trilobites. It has a look which suggests the mysterious Egyptian figures of ancient courtiers ! The head or cephalic shield is much developed, and on each side is prolonged into two spines half as long i88 OUR COMMON BRITISH FOSSILS. again as the body. Like the Agnosttis and several others, the Trinucleus had no eyes. In this respect we find the various genera of Trilobites differing very much from each other. Some have a very large number, as Asaphus tyrannus ; and thence we find them decreasing until they are absent altogether. All the genera of the order Trinucleidce, however, are not eyeless ; and this illus- trates the uncertainty with which the power of vision seems to have heen distri- buted among these ancient crustaceans. Doubtless,this variation was the result of special conditions of existence, eyes being al- ways possessed when they were required. Thus the living male Bopyrus, or shrimp-parasite (Fig. 149), has rudimentary eyes, Fig. ^.-Paradoxides Tessini. wh jj st the f emale has none; but this is entirely due to the very different habits of life of the two sexes. Trinucleus is abundant in the Caradoc shales of Shropshire. From the Cambrian to the Carboniferous forma- tions we find certain Trilobites peculiar to the various TRILO BITES AND OTHER FOSSIL CRUSTACEA. 189 geological systems. Thus, Paradoxides and Agnostus are peculiarly Cambrian ; Trinucleus and Asaphus are almost exclusively Lower Silurian ; Phacops and Calymene are markedly Upper Silurian ; Brontes and Harpes are among characteristic Devonian fossils ; whilst Phillipsia and Griffithsides are genera of small Fig. 152. Paradoxides Davidis. Fig. 153. Homalanotus. Trilobites the last of their race which are peculiar to the Carboniferous limestones. Undoubtedly many of the fossil Tribolites we meet with in any of the above rocks are moults that is, portions of the carapace thrown off after the manner of the shells of lobsters and crabs. This igo OUR COMMON BRITISH FOSSILS. moulting process appears to have peeled off the ex- ternal hard shell in two or three pieces. Thus, the head-piece, or cephalic shield, is usually found alone ; the thorax, or ringed part, is also abundantly found separate ; whilst the pygidium, or tail, is frequently met with apart from the others, although it is usually adhering to the thoracic part. Of course, animals Fig. 154. Ogygia Buchii. which have died and been buried in the mud are found with all the above parts adhering to each other. The carapace or shell differed in its character in various species. In some it appears to have been very thin, in others harder. It may have been more or less chitinous, after the manner of the elytra of beetles, strengthened by the presence of limy matter. TRILOBITES AND OTHER FOSSIL CRUSTACEA. 191 In the Carboniferous Trilobites (Phillipsia, etc.) the carapace seems to have contained more limy matter in its composition than other species. In this genus we always find the moultings in the two parts of body and tail, and head. In the Calymene (Fig. 140) the thoracic or ringed part is frequently found by itself, Fig. 156. Head shield and Caudal shield QiPhillipsia. Fig- **>$. PJiacops caudatus. Fig. 157. Trinuclens LloydtL and not seldom the rings are detached, as if the whole mechanism of the coat-of-mail-like armour had be- come loosened and got scattered about. Undoubtedly the chemical composition of the carapace differed accordingly as the habits of the Trilobites varied. 192 OUR COMMON BRITISH FOSSILS. The Cambrian Trilobites, as a rule, differ from their Silurian descendants and representatives in having a large number of rings or segments to the thoracic (or middle) part of the body: The tail part (caudal shield) is, however, less developed than in the Silurian species. The side-lobes of some genera, Paradoxides and Acidaspis, are fringed, and, in the case of the latter, further adorned with spines. Some of these may have been merely sexual distinctions, although we are now forced to regard them as specific. Dean Buckland and many other naturalists regarded an isopod crustacean abundant in the seas around Tierra del Fuego and the Straits of Magellan, as nearly allied to this group of Trilobites. This crustacean is called Serolis. Its cephalic shield has compound sessile eyes, arranged in half-moon-shaped lobes exactly like those of some Trilobites. The segments or joints of the thoracic portion of the body are fringed, as in Paradoxides, and there is a movable caudal or tail shield, as in Phacops caudatus (Fig. 155), an abundant Silurian Trilobite. Only the antennae and mouth-organs differentiate them. But these are very thin and weak, and after death may soon be detached as various geologists believe was the case with some Trilobites. The legs are fitted for crawling about, but, as is frequent in animals living in sea- water, they are also weak and thin. The Serolis is a slow crawler and swimmer, and is usually found on sea- weed. Some geologists have imagined that a few TRILOBITES AND OTHER FOSSIL CRUSTACEA. 193 Trilobites had generic relations with the common Apus of our ditches and ponds. Sufficient has been said, however, to show how large a middle space the numerous family of Trilobites occupy. At the one extreme they nearly touch the king-crabs and at the other the aborted shrimp-parasites, as in the case of Agnostus. Perhaps the living Serolis better represents the average forms of Trilobites than any- thing else. Fig. 158. Serolis Fabrtcii. Fig. 159. Under side of Serolis Fabricii. a, eyes ; b, feet ; c, organs of mouth (recent). The Cambrian strata have recently been ex- tended upwards as high as the "May Hill" group, so as to include rocks formerly classed as Lower Silurian. They are well represented in many parts of Great Britain, notably in North Wales and the Lake districts. Trilobites of various genera may be met with in many localities which are usually visited by tourists for the sake of the scenery alone. It is one of the privileges of the geologist, that his calling O 194 OUR COMMON BRITISH FOSSILS. takes him to some of the wildest, grandest, or most beautiful scenes in nature. Although, in not a few instances, rich fossiliferous strata occur in unlovely places, amid densely populated neighbourhoods, as at the Wren's Nest, near Dudley ; yet as a rule fossils are most abundant where the rocks crop out along mountain or hill sides or sea-cliffs. In searching for them he startles the grouse or the moor-fowl, and finds many a lovely mountain plant solitarily bloom- ing. Scenes of unsurpassed loveliness are thus re- vealed to him, in the grandeur of rock-masses, or the panoramic stretch of the valleys below and beyond. What wonder if men who have had to toil the year round for the bread which perisheth, in dingy offices or amid the noise and bustle of machinery, should so value the week or two of summer holiday, which enables them to devote themselves to those geological pursuits which have all the charm and excitement of hunting without any of its cruelty ! For, if the geologist wishes to change the area of his labours from the mountain-side to the seaside, he can do so at leisure, without interfering with his success in fossil- hunting. Some of the very best sections are those to be seen in our sea-cliffs ; some of the richest fossi- liferous districts are where the student may be taking in a fresh stock of health whilst he is following his bent, and is silently impressing on his memory scenes of beauty which will last as long as his own individuality ! Perhaps it is this direct contract with TRILOBITES AND OTHER FOSSIL CRUSTACEA. 195 Nature in all her varied moods which makes such enthusiasts of geologists. Not even botanists are more devoted to their hobby ; and it is undoubtedly this enthusiasm which makes geological investigation independent of companionship for success. The absorption of most, if not all, of the Lower Silurian rocks into the Cambrian system has, of course, largely increased the number of localities where fossils are to be obtained. The Mene- vian beds near St. David's, in South Wales, are exceedingly rich in Trilobites ; among which Paradoxides Davidis, the largest of its order, is abundant. This species sometimes attains a length of two feet, and is, there- fore, strongly contrastible in this respect with the little Agnostus (Fig. 1 50) and the Phillipsia (Fig. 156). The South Welsh Valleys are comparatively little explored, although the geological student might do so to his double advantage, for they are equally rich in scenery and in fossils. Monmouthshire presents an area of country where we have, perhaps, a more varied geological outcrop than anywhere else in Great Britain. Near Newport a patch of Silurian strata Fig. 1 60. Apus productus (recent). 196 OUR COMMON BRITISH FOSSILS. abounds in several species of Trilobites, notably Asaphus and Ogygia (Figs. 139 and 155). Buiith has been noted for the number and beauty of its Ogygia Buckii. Maentrog and Port Madoc have long been cele- brated for their rich yields of Trilobites. The student may obtain them, in many places, from the slates which build up the walls by the roadside, whilst in the quarries there are usually bands or seams espe- cially full of them. Few localities are better worth a visit, for we are here within the charming circle of Snowdonia. The lower Lingula flags are well deve- loped at Maentrog, and one Trilobite is so abundant in them that it was proposed to call them " Olenus " beds. Two species of the obscure little Agnostus are associated with it, along with various other fossils. At no great distance up the higher parts of the valley is Festiniog. A diminutive railway, with cars of the same proportion as the narrow diameter of its " per- manent way," runs up one side of the valley to Fes- tiniog, and the geological student can take advantage of it in his rambles, and thus pass over the outcrop of beds rich in Trilobites. A locality for Cambrian Trilobites is the neighbourhood of Dolgelly, a district whose magnificent scenery of wild mountain and umbrageous valley is annually drawing to it a larger number of tourists and visitors. Here Conocoryphe y AgnosttiSy etc., may be found in certain places in tolerable abundance. The student might advan- TRILOBITES AND OTHER FOSSIL CRUSTACEA. 197 tageously work his way to Dolgelly by Tremadoc, at which place he will find abundant employment for his hammer. At the village of Penmorfa the slates are often crowded with remains of Trilobites. Garth Hill is also a capital collecting-ground. In many places the Llandeilo flags are so full of Trilobites that Sir Roderick Murchison gave them the name of "Trilobite Schists." Perhaps the neighbourhood of Builth is the best place for obtaining them. Several species of Ogygia occur, associated with numerous other fossils. The Cambrian and Silurian rocks of the Lake District are not so abundant in Trilobites as those of North Wales and Shropshire, although I have found them in the rich fossiliferous shales of Apple- thwaite Common, and on the Lancashire side of Windermere chiefly Asaphus. Calymene, Homalo- notuS) and others occur in the Dalton shales, of Upper Llandeilo age. In the Coniston limestone, also, we have Illcenus, Cheirurus^ Agnostus, etc., all of them well-marked genera of Trilobites. In the Silurian proper (the upper Silurian of geolo- gists only a few years ago) we find Trilobites reaching their maximum of existence, both in genera, species, and individuals ; and we have tolerably certain evidence that after this epoch they began to decline until they became extinct. In the loveliest parts of North Wales, as at Conway, the Devil's Bridge (near Pentre Voelas), Craig Hir, and at Mynydd Fronfrys, 198 OUR COMMON BRUTISH FOSSILS. about four miles from Llangollen, among the moun- tains, we find abundance of fossils, and among them are various species of Pkacops, Calymene, etc. The pretty village of Woodhope, near Hereford, is another charming collecting-ground, rich in Upper Silurian fossils ; and here we find Illczmis, Homalonotns, Phacops, etc. Trilobites are also abundant in the Wenlbck shales forming part of the Malvern Hills. Of the Dudley limestone and its treasury of these peculiar ancient forms of life, I have already spoken. The neighbourhood of Ludlow has also long been known as a rich storehouse of Trilobites of various species and genera. In the Devonian beds it is only here and there we can meet with Trilobites in any abundance. One of the best localities is Newton Abbot, in Devonshire, where the limestone contains numerous Trilobites. The Pilton beds yield certain species of Phacops in plenty. The Trilobites are most abundant in the Middle Devonian strata of England, owing to the probable fresh-water conditions under which most of the other beds 'were deposited. The Carboniferous limestone, both of England and Ireland, is frequently rich in Trilobites of the genera Phillipsia and Grif- fithsides, named after two distinguished geologists. At Castleton, in the Peak of Derbyshire, along the outcrop of the strata forming Tre-cliff, is a band especially crowded with Phillipsia; and in the curious gorge to the immediate south of the cavern TR1LO BITES AND OTHER FOSSIL CRUSTACEA. 199 called " Cave Dale " (undoubtedly an ancient cavern with the roof worn off) we may find this Trilobite associated with a wonderfully abundant collection of other fossils. At Salt Hill, Clitheroe, in Lancashire, the shales which part the limestone bands are seen crowded with the evidently moulted remains of Phillipsia. The large number of species, even of British Trilobites, obtained from the various strata above mentioned, are grouped into certain families. We have first the Agnostidce, characterized by their small size, by the head and tail being covered with two nearly equal shields, and the possession of not more than two body-rings. This family was eyeless. The OlenidcB or Paradoxidce had long bodies, with numerous free segments. The caudal or tail shield was small ; the side lobes were prolonged into curved spines. A large number of the more ancient genera of Trilobites belong to this family. The Asapkidce were tolerably large oval Trilobites, with smooth carapaces, and possessed about eight body-rings. Ill&nus and Ogygia are included in this group. The Trinucleidcs had a large head-shield, ending in two long spines, one on each side. The body-rings were five or six in number. The Cheiruridce included seven distinct genera, which had a geological range from the Cambrian to the Devonian strata. The facial sutures of the head-shield ended on the outer margin. The number of rings or segments was eleven, and these 200 OUR COMMON BRITISH FOSSILS. were free at their ends. The Calymenidce had cara- paces roughened over with granules or tubercles, and the number of body-rings was usually thirteen. In HomalonotuSy one of the two genera composing this family, the body-rings are not so distinctly trilobed as usual. PhacopidcB was a family of Trilobites with large facetted eyes. The number of body-rings is eleven. The Lichadce had small head-shields, and a tail or pygidium with a broad limb. It contains only the genus Lichas. The Prcetida includes the Carbo- niferous genera Phillip sia and Griffithsides. Their number of body-rings was usually nine. The carapace of Phillipsia is generally roughened with granules. Acidaspidce had a very ornamental carapace, with eight to ten body-rings, and the segments of the side lobes (pleurae) directed backwards. The tail had also two or three segments, furnished with prominent spines. The Bronteidcs had a large expanded tail or pygidium. The Harpeidcs were noted for the horse- shoe-shaped head-shield, whose angles were greatly prolonged. The body was numerously jointed, usually with twenty-six segments. Only one genus, Harpes, belongs to it. Lastly, we have the Cyphaspidce, whose head-shield was also prolonged into spines, and the carapace marked by spiny or pitted surface ornamenta- tions. The number of body-rings varied in the different genera from ten to twenty- two. These are among the less common of the Trilobites. I have given the principal place to Trilobites TRILOBITES AND OTHER FOSSIL CRUSTACEA. 201 among the fossil Crustacea on account of their singular interest and beauty ; but nearly all other living groups of this family are represented in the fossil state. We have some occurring in the latter condition which have long been extinct, as the Eurypteridce, for instance. Its members were both abundant and huge of size during the Upper Silurian and Devonian Fig. 161. Recent Entomostracan (magnified"). The upper figure shows the two valve-like parts of the crust. periods. Specimens of this group may be seen in nearly all our British museums. The Phyllopoda were among the first crustaceans to appear in the early seas, and were represented by Hymenocaris. The Ento- mostraca are the lowest organized among this varied class of animals, and from the Lower Silurian rocks upwards and onwards into the seas, lakes, and rivers 202 OUR COMMON BRITISH FOSSILS. of modern times, we rarely lose sight of them. The shales overlying the Coal-seams frequently look as if somebody had sown millions of pins' heads there : these are the fossil Cyprides, allied to the water-fleas seen in our modern ponds and tarns. Shales, slates, and thin limestones not unfrequently owe their fissile character to the abundance of Entomostracans of various kinds. The large and beautiful Estheria a form still existing, and delighting in brackish water, and whose two shells so much resemble those of a bivalve mollusc (even in the recent state) that a young student may easily be deceived into thinking he has found another sort of animal occurs first in the Devonian rocks, and is also found in the Carboniferous and Permian series. In the upper Trias of Warwick- shire and Leicestershire it is not unfrequent ; indeed, it is one of the few fossils found in these strata, which are so rich in evidences of physical action rain-drops, sun-cracks, ripple-marks, etc. and so poor in palaeon- tological souvenirs. To the naturalist there are few classes of the world- wide (and also old world) group of Crustacea more interesting than the Cirripedia, of which our modern acorn-shells (Balanus), seen clustering after their sessile fashion on the rocks, to the detriment of naked feet when bathing and the stalked kinds (Lepas) seen attached to fragments of old wreck-wood which has long been floating about and is at length cast ashore. TRILOBITES AND OTHER FOSSIL CRUSTACEA. 203 In these animals, curious and wonderful as they are in their power of adaptation, we find a class which are zoologically more highly organ- ized in their larval state than in their adult condition. The doc- trine of evolution admits of 'retro- gression as well as of progression, and the Cirripedia are all, with- out an exception, illustrations of the former. Consequently, for the philosophical student to find fossil specimens of a group illus- trating retrogression is an inter- esting fact. It would appear as if the stalked barnacles (Lepadidcs) pre- ceded in geological time the sessile kinds. Thus we find a _ , .. r i i Fig. 162. Scalpellnni vulgare genus of the former so far back (recent). as the Upper Silurian rocks, in which Turrilepas occurs. In the Rhsetic strata we have Polli- cipes ; we come across them fre- quently in true marine strata (and all of this group are of a thoroughly marine character), Fig- 163. Bai . 1,1 r\ TL A. j.1. Figs. 162, 163. Specimens of through the Oolites, mtO the recent stalked and sessile White Chalk, where Darwin mentioned thirty-two species as having been dis- 204 OUR COMMON BRITISH FOSSILS. covered. The White Chalk of Norfolk has, I believe, proved richest in these stalked cirripedial forms. The peculiar angular and striated plates are by no means uncommon in the Chalk-pits about Norwich, and they are found fossilized (generally on the out- side) on the flint nodules as well. Real sessile Cirripedes occur first in the Lias. Verruca stromia is common (in detached plates) in the Coralline and Red Crags. Species of sessile barnacles still in existence as, for instance, Balanus porcatus, etc. cover the upper surfaces of all the large stones at the bottom of the Red Crag strata near Ipswich and Felixstowe ; and so firmly do they cling that I have frequently seen the pauper-broken flints (obtained thence) in fragments, with their share of thickly coated fossil barnacle-shells still adhering to them thanks to the strong precipitation of iron-oxide which cemented them more firmly than ever they intended to their original settling-place more than a quarter of a million of years ago ! What we call true crustaceans are hardly repre- sented by that early " shrimp," the Hymenocaris. All zoologists know that the true Crustacea are now separated into the long-bodied kinds (Macrura), such as the lobsters and crayfish ; and the short-bodied kinds (Brachyura), as represented by our modern edible crab. Somewhere half-way between these we may place the Anomura, of which the soft-bellied, hard-clawed, and evidently anomalous " hermit-crabs " are examples. TRILOB1TES AND OTHER FOSSIL CRUSTACEA. 205 It has frequently been pointed out that by care- fully studying the ernbryological development of any individual up to its adult state, we may get a glimpse of the stages through which the genus or species, or even the family, has passed in its evolutional develop- Fig. 164 Phases in the Larval Development of the Crab : a, Zcea stage ; b, advanced (or megalopa) stage ; c, earliest completed stage. ment. Thus the young larvae of the common crab whose aborted and contracted body is popularly known as the " apron " in the first three or four of its early stages, has a properly jointed body like the lobster. The long-bodied crustaceans preceded the short-bodied ones in order of geological time ; so that we have here an indication that the short-bodied crabs are descended from long-bodied and lobster-like ancestors. The short-bodied crustaceans (called Brachyura on Fig. 165. Carapace of Notopocorystes. (Cam- bridge Greensand). 206 OUR COMMON BRITISH FOSSILS. that account) have not been found in rocks of older formation than the Lower Oolite. There we get a generic form, named by Dr. H. Woodward Paliczna- chus. The long-bodied Crustacea (Macrurd} had appeared in the stage of creation before the end of the Primary period, as Anthrapal&mon the Phyllopods (a lower group) having preceded them. In many English localities the fossil Crustacea are very beautifully preserved, and are unquestionably among the gems of the cabinet when properly worked out. In the Oolitic and Cretaceous rocks we have the well-known generic type Eryon, not at all uncom- mon. The chalk of Hertfordshire has yielded to a friend of mine (who was geologically inclined, and wanted a " hobby ") a number of new forms of fossil crayfishes. The real fact was they wanted hunting up. When the student has learned to recognize crus- tacean structure, and he sees a bit of it cropping out in the chalk, he must work away with his pocket- knife and tooth-brush until the whole of the probably buried-up crustacean is developed. Chalk is a capital rock for allowing of this ; the harder Oolitic lime- stone is not so easily persuaded to give up its dead. When we came to the Tertiary formations, espe- cially to the Eocene or rather, the London Clay representative of that interesting formation the higher-developed fossil crustaceans are not uncom- mon, and, in places, even plentiful. The London Clay of the Isle of Sheppey is a sort of crustacean TRILOBITES AND OTHER FOSSIL CRUSTACEA. 207 cemetery. How abundant they are there may be best stated by saying that Sheppey fossil lobsters may be bought in the Strand geologist's shop for sixpence each a good deal cheaper than the price of the recent lobsters in the other shops, a door or two away. Still, at Sheppey, and elsewhere, these fossil crus- taceans have to be dug out of the clay, or else the collector takes advantage of the weather and the waves having washed them out of exposed cliffs. In Suffolk we are very advantageously placed in this respect. The weather and the waves washed all the harder Eocene fossil Crustacea out of the London Clay, perhaps during the Eocene period, and they were collected together in hollows and other protected places. The area these fossils occupied subsequently became a sea-floor, and the old derivative fossil crustaceans were thus covered up by the dead shells of a later period, and were even subjected to the indignity of having their petrified corpses made use of as settling-places for Red- Crag barnacles (retro- grade representatives of the class of which they were aristocrats) ! Anyhow, you can get any number of fossil crabs and lobsters Brachyura, Anomoura, and Macrura in the heaps of phosphatic nodules collected together and awaiting carting, in the neighbourhood of the " coprolite " pits about Ipswich and Felixtowe. The commonest of these fossil crustaceans are Xanthopsis, Thenops, Zantholites, Hoploparia, Archceo- 208 OUR COMMON BRITISH FOSSILS. carabus, Dromilites (possibly a fossil hermit-crab), etc. Some of these derivative specimens are very perfect, others are water-worn ; but all are imbedded in what was once a phosphatic paste. Singularly enough, marine phosphate deposits are frequently remarkable for their fossil crustaceans ; as, for instance, the Greensand " coprolites " of Cambridgeshire, where we have an abundance of the carapaces of Notopocorystes. In the Silurian formation we have certain thin beds of phosphorite, or phosphate of lime, more or less associated with Trilobites, and perhaps partly pro- duced by their subsequent chemical transformation ; for we have to remember that the carapaces of crusta- ceans are remarkable for the quantity of phosphate of lime which enters into their composition. ( 209 ) CHAPTER VIII. FOSSIL SEA-MATS (POLYZOA). FEW people, possessed of natural history tastes, can have examined the odds and ends thrown upon the sea-beaches of the watering-places in the summer without noticing that the larger seaweeds, and even the bases of the numerous corallines, are matted or encrusted with peculiarly lovely lace-like organisms, which bleach to a pure white when dead. A magni- fying glass shows clusters of cells, the residences of tiny and relatively highly organized little creatures which live together in a neighbourly fashion all of them the descendants of an original ancestor, like the "ham " of an early Saxon chief. The cells are variously shaped, adorned or defended by spines, etc., so that species can easily be multiplied. A good deal of lime is employed in the walls and partitions of these dwellings, hence their durability after death. Some genera are remarkable for the relatively large quantity of lime used in their common structure or Polyzoaria, as, for instance, Eschara, etc. p 210 OUR COMMON BRITISH FOSSILS. Others are largely chitinous, as the common sea-mats (Flustra], whose seaweed-like fronds often appear as algae in seaside albums, but which are really an innumerable colony of little cells placed back to back. Fig. 166. Recent Polyzoon (Membranipora), encrusting Sea-weed. Stones, rocks, oyster and other shells are fre- quently invested with the spreading growth of these lovely organisms. And in this respect we find their habits have not altered since the Silurian period, for FOSSIL SEA-MATS. 211 numbers of the pretty corals, shells, etc., in the lime- stones of the Silurian, Devonian, Carboniferous, Permian, Oolite, Chalk, and Crag formations are more or less covered with fossil Polyzoa. Indeed, in the Crag beds we often find univalves so thickly encrusted with growths of these animals that the mollusca must have been finally killed by the mouths of their shells being closed. Recent fronds of the Laminaria seaweed just thrown up are sure to be Fig. 167. Recent Polyzoon, showing Polyps protruded (magnified). found with living patches of these lace-like organisms upon them. Let the observer snip off a strip with such a colony upon it, and place it in sea- water. If it is of a dull glassy appearance, and not an opaque white, the colony is probably alive. When the strip is placed in a zoophyte-trough, after a short time, the observer will see suddenly popping out of each cell a cluster of lily-like petals, sixteen or more in number. 212 OUR COMMON BRITISH FOSSILS. These are the ciliated tentacles, and a higher power (say a half-inch objective) will show the cilia actively at work on the lobe-like tentacles, so that the sea- water is thrown into a state of microscopical commo- tion thereby, and particles of floating matter are seen whirled about, and finally gathered by the vortex into the mouth of one of the little creatures, whose dia- phanous body enables us to trace its passage to the stomach. The slightest jerk, or even the falling of a shadow, is quite sufficient to cause these zoophytes Fig. i68.-ceiisof^*m/>r to withdraw within the pro- tection of their cells to reappear immediately afterwards. All of the Polyzoa are really highly organized creatures, possessed of a mouth, stomach, intestinal canal, anus, and nervous and muscular systems. They are very nearly related to the Ascidia or " sea-squirts " (especially to those social groups of the latter family we see clustered on seaweeds, such as Botryllus). The absence of any solid parts in the " sea-squirt " family has of course prevented our finding any traces of them in the fossil state. This is to be regretted, especially as the tadpole-shaped young of these Ascidians so much resemble the internal organization FOSSIL SEA-MATS. 213 of the lowest of the Vertebrates the order of fishes represented by the Lancelet (Amphioxus lanceolatus) that we may regard them as a bridge connect- ing the Invertebrate and Vertebrate divisions of the Fig. i6q. Common Sea- Mat (F lustra truncate!), natural size, recent. animal kingdom. Indeed, the larvae of the Ascidians are so much more highly organized than the adults that Professor Ray Lankester and others regard the Ascidia as degraded Vertebrates ! The geologist 214 OUR COMMON BRITISH FOSSILS. hardly doubts that sea-squirts were in existence in the earlier seas of the globe. Had we any fossil evidences of them, they might be serviceable in tracing the original connection between the Inverte- brates and the Vertebrates. These sea-mats are also related to another group of animals which, as we have already seen, played a very active part in the seas of the Palaeozoic epoch the Lamp-shells or Brachiopoda. In fact, sea-mats, Fig. 170. Cells of Flustra (magnified 60). Fig. 171. Social Ascidians (Botryllus), on Sea-weed (natural size). sea-squirts, and lamp-shells are all grouped in the division Molluscoida. It is a common error to associate the sea-mats with the Corallines. In reality these two groups of animals are widely separated by zoological characters, although not unfrequently they greatly resemble each other as far as external characters go. The most beautiful, and perhaps also the most extensive, of the ancient sea-mats were the Fenesteldi&l. FOSSIL SEA-MATS. 215 They abound in the marine deposits of all the Palaeo- zoic rocks, from the Lower Silurian upwards. The Fig. 172. Fenestella. pleleia. geologist finds them creeping over shells and encrinite stems, and they are often spread out in a fan shape. Figs. 173, 174. Fenestella filebeia (Carboniferous limestone, Halkyn, etc.). Fig. i-j^.Glauconome Jlexicarinata. The limestone shales of the Silurian and Carboniferous formation contain them in great plenty, as is indicated 216 OUR COMMON BRITISH FOSSILS. by the fact that Mr. G. R. Vine obtained, by washing from six to eight tons of Wenlock shale, a vast number of specimens of fossil Polyzoa, among which the genera Fig. 176. Fenestella nodnlosa (Carboniferous limestone and shales). Fig. 177. Glauconomg elegans. Stomatopora, Spiropora, Glauconome, Hornera, Fenes- tella, etc., were abundant. Certain localities are dis- tinguished for the abundance of fossil sea-mats they Fig. 178. Vinr.ularia. Fig. 180. Portion of Polypora (magnified). (magnified). Fig. -i^. Fenestella membranacea. (magnified). have yielded, but it is really because there have been enthusiastic geologists to work them. Mr. Vine has astonished palaeontologists by the great number of FOSSIL SEA- MATS. 217 new species he has obtained by carefully washing, sifting, etc., deposits likely to contain Polyzoa in nearly all our British marine strata. Mr. John Young, F.G.S. of Glasgow, has similarly worked the Lower Carboniferous beds of Scotland, and has carefully brought to light a wonderful variety. Hairmyres is perhaps the best hunting-ground for these delicate little fossils in Scotland, and the Halkyn Mountains in Wales. But they are easiest seen on the surfaces Fig. 182. Polypora tuberculata, showing arrangement of cells. Fig. 183. Diastopora Oolitical a, natural size. of the thin dark bands of shale which frequently occur in all limestones. The Oolitic limestones are frequently rich in Polyzoa, of which perhaps Diastopora is the com- monest genus, and Bidiastopora, Eschara, and Idmonea the next. In the Chalk (a deep-sea deposit and the Polyzoa seem to love clear water, as is proved by the abundance of recent species on the " Gulf-weed ") the 218 OUR COMMON BRITISH FOSSILS. sea-mats attain their minimum of beauty. About two hundred species are said to have been already described from this important formation, most of them belong- ing to the genus Eschara. I have found that the best objects on which to look for Cretaceous fossil sea- mats are the naked tests of such sea-urchins as Ananchytes and Galerites. Very few of these fossils, excavated from the Norfolk Chalk, and then carefully and tenderly washed, but have a sprinkling of fossil Fig. 184. Cells of Diastopora Oolitlca (magnified). sea-mats over them. Not a few may be found com- pletely invested with them (all but the base), looking as if the " fairy-loaves," as they are called, had been packed away in delicate Honiton lace, and all had been fossilized together. We find these Cretaceous sea-mats actually silicified, which shows what a great chemical change is often included in fossilization. We do not lose sight of fossil sea-mats in our British Eocene deposits, but the place to find Tertiary FOSSIL SEA-MATS. 219 species in superabundance is the " Coralline " Crag, which took its geological name from their numerical abundance, in the early zoological days when sea- mats and sea-firs (Hydrozoa and Polyzoa) were grouped together as " corallines." Fig. 185. Dlastopora ventricosa; NS (natural size). The "re-deposited" Coralline or White Crag is best seen in the neighbourhood of Aldborough and Orford, in Suffolk, where it is about eighty feet thick, and of a pretty cream-colour. The fossils in this bed are abundant, but every one is encrusted with a 220 OUR COMMON BRITISH FOSSILS. growth of fossil Polyzoa, many of them allied to, if not identical with, existing kinds, such as Cellepora, i Fig. 186. Diastopora ventricosa (highly magnified) Membranipora> Hornera, etc. Others are locally ex- tinct, and can only be found in warmer seas. Near Fig. 187. Cells of Diastopora Oolitica (highly magnified). Fig. 188. Fascicularia aurantiui (Coralline and Red Crags). Orford the young geologist will find plenty of round balls, which, when split open, reveal a radiated struc- FOSSIL SEA-MATS. 221 ture, each surface of this convoluted and radiated structure showing the latticed appearance of a sea- mat. This is Fascicularia aurantium. Other common kinds (about which Professor Busk wrote a mono- graph for the Palaeontological Society) are several species offfornera, of which the most beautiful, perhaps, is H.reteporacea; several species ofAtveotaria, the finest and largest being A . semiovata ; of Eschar a y and Celle- pora. Some of the latter species are branched and resemble corals ; others, as Cellepora edax, have crept over, covered, and suffocated the inhabitants of uni- valve shells. Hydractinia is also found in the fossil state in the Coralline Crag, covering shells in a similar manner. Other abundant sea-mats are various species of Lepralia (found covering the interiors of empty bivalves), Heteropora, and others which the collector will not fail to gather about Orford and Aldborough, in greater abundance than his powers to remove them will prove available. 222 OUR COMMON 1 BRITISH FOSSILS. CHAPTER IX. FOSSIL LAMP-SHELLS (BRACHIOPODA). REFERENCE has already been made to this class of fossils as being by far the most numerous in the Primary rocks. The limestones are not unfrequently wholly composed of their ancient shells. They are also very abundant in the Secondary strata, although less numerous than in those preceding them ; whilst in the Tertiary marine deposits they are much scarcer, and in the Recent or present period comparatively rare. Thus the Geological Record presents us with the interesting spectacle of the rise, growth, decline, and fall of one very large class of marine animals. Notwithstanding this inability on the part of the Brachiopoda to compete successfully in the struggle for existence with the more highly organized mollusca, it is very singular how persistently certain genera have maintained their distinctive features through periods of time as vast as that which has extended from the Silurian epoch to the present day, like the Lingula genus, for instance, has done. One can FOSSIL LAMP-SHELLS. 223 hardly distinguish the fossil Lingulas, found so abun- dantly in the Lingula Flags (whence the name of the latter deposit), from those still living, and possessed of the same kind of peduncle or anchoring appendage, as well as the same semi-horny structure of shell. The pretty Terebratula striata, found not uncommonly in the Chalk near Nor- wich, is believed to be even specifically identical with a form still living in British seas, but known by another name. Mr. Thomas Davidson, F.R.S., in his exceed- ingly lucid papers on " What is a Brachi- opod ?" published in the Geological Maga- zine for 1877, says, "What wonderful changes have been operating during the incalculable number of ages in which the creation and extinction of a large number of genera and thousands of species have taken place ! Some few only of the primordial, or first created genera, such as Lingula, Discina, and Crania, have fought their way and struggled for exist- ence through the entire sequence of geo- Fig. 189. z,/- . gular anatina, logical time : many were destined to a (recent), show- ing peduncle. comparatively ephemeral existence, while others had a greater or lesser prolongation of repro- duction." It seems as if the very name of this order contains a fossil idea that these animals employed their long 224 OUR COMMON BRITISH FOSSILS. coiled arms for locomotive purposes. Such was the origin of the term Brachiopoda, or " arm-footed." And, although Professor King endeavoured to change the name to Palliobranchiata (or " mantle-gilled "), the latter somehow has not " stuck." Suffice it to say, therefore, that the long arms of the Brachiopoda so distinctive a feature in their anatomy and physi- ology are only labial appendages to the mouth, bringing food by means of their currents, and air as well ; but Fig. 190. Lingula . . '. (Silurian forma- are never employed as locomotive tion). organs. The young of the Brachiopoda^ like those of such well-known bivalves as the common oyster, are free- FJ^. i 9I ._ Lingula Lewisii Fig. ig-z.Leftana transversals (Silurian formation). (Silurian). swimmers. In this stage they are believed by some to show evidences of annelid affinity just as Mr. Harmer has recently demonstrated that young Polyzoa show affinities with the Rotifercz. It is interesting thus to see the hitherto unstudied stages of embryological development enabling the naturalist to join hands across a space which the boldest investi- gator would not have dreamed of half a century ago ! FOSSIL LAMP-SHELLS. 22$ The common name of "lamp-shells," given both to fossil and recent species of Brachiopoda, is due to the resemblance of the two valves, ventral and dorsal (minus the handle), to an old Etruscan or Roman Fig. 193. A try pa re- ticularis, showing internal spiral coil (Silurian formation). Fig. 194. Obolus, show- ing internal loop. r ig. 195. PentamerusKnightii Jpper Silurian limestone). lamp. The ventral valve is the larger, and usually has a perforation in the upturned beak, exactly like that through which the wick passed in the ancient Fig. igG.Pentamerus, showing internal plates. j.Orthis elcgantula (Silurian). lamps. Older naturalists were, of course, more affected by external appearances than by internal structure even supposing they took any notice of the Q 226 OUR COMMON BRITISH FOSSILS. latter and by them this group of fossils were called Lampades. The structure of the shells of Brachiopoda (as Fig. 198. Cranies, showing exterior and interior of shells. Dr. Carpenter has clearly shown) is different from that of the bivalves or Lamellibranchiate mollusca, Fig. 199. Strophomena depressa, showing exterior and interior of valves (Silurian). although it represents one stage in the formation of the shells of the latter that of the outer layer. Fig. 200. Stropkomena Fig. 201. Rhynchonella pugnus rugosa. (Carboniferous limestone). Owing to the large size of the " arms " (as they are still technically called) of most of the Brachiopods, the interior of the valves contain remarkable struc- FOSSIL LAMP-SHELLS. 227 tures, which are useful to the palaeontologist in enabling him to classify these fossils. In many genera there is a limy, brittle, and delicate structure, assuming either the shape of "plates," "loops," or " spirals." Very frequently we get fossils in which Fig. 202. Orthis striatula (Devonian). Fig. 203. Interior of Spi-iifer^ showing spiral coils. these are still preserved, and the experienced worker among the limestones of the Palaeozoic rocks knows that the " chert-bands " that is, the accumulation of Fig. 204. Sfiirifer trigon- alis, showing internal coil where portion of shell is removed (Carboniferous limestone). Fig. 205. Spirifer speciosus (Devonian). chemically combined silica and lime (analogous to the flint-bands and nodules of the Chalk) are the best places in which to look for the internal spirals, loops, plates, etc., of the fossil Brachiopods. For in such places the outer shell has been dissolved away, and the internal and more delicate " skeleton " has 228 OUR COMMON BRITISH FOSSILS. been preserved, and is now perhaps encrusted with microscopical crystals of silica. In all cases, this internal loop, spiral, or whatever shape it may have assumed, is merely the mechanical Fig. 206. Spirifer strtatus : a, exterior of shell ; b, interior, showing spiral coils ; c, portion of coil (Carboniferous limestone). support of the brachial or labial coils, about which remarks have already been made. Not unfrequently this internal loop (as in some Terebratulcz) occupies more than half of the interior Fig. 207. Rhynchonella Fig. 208. Terebra- pleurodon (Carboniferous tula hastata (Car- Fig. 209. Spirifer cuspidatus limestone). boniferous limestone). (Carboniferous limestone). of the shell. In the Spirifera there are two conical coils or spires (whence the name of the genus " spire-bearing "), the apices of which are on each side. In the Pentamerus we have it developed as a series of plates , dividing the interior into five parts, like FOSSIL LAMP-SHELLS. 229 chambers ; so that this ancient genus of Brachiopods takes its name from the circumstance. In the Rhyn- c/ionellidcs there are two internal short, slender, and curved plates. What we have to note, however, is Fig. 210. Rhyachonella (Car- boniferous limestone). Fig. 211. Productus punctata (Car- boniferous limestone). that all of these mechanical structures are merely adaptations, to better enable the " arms " to do their work effectively. It is in the smaller or dorsal valve Fig. 212. Productus giganteus (Carboniferous limestone). that this skeleton is usually seen. No skeleton is found within the genera Lingula, Lingulella, Obolus, Discina, Crania, etc. In the Terebratulce it is often 230 OUR COMMON BRITISH FOSSILS. largely developed, and assumes such a variety of forms that it proves useful for classificatory purposes. The spiral coils are found in Spirifer, Spiriferina, Athyris, Retzia, Merista, etc. In the Rhynchonellidce Fig. 213. Orthis resupinata (Car- boniferous limestone). Fig. 214. Productus scabriculus (Carboniferous limestone"). the fleshy arms are usually supported by the pair of short plates alluded to, and sometimes by spirally coiled ribbons, closely pressed together, and having the apices of the flattened spires meeting within, in- stead of the reverse way, as in the Sfirifera. This struc- ture is best and most com- monly found in A trypa. The enormous size of the plates inside the Pen- tamerus is finely seen in the large and beautiful Upper Silurian fossil Pentamerus Knightii, which frequently splits open with great ease along the planes or faces of these internal divisions. The Cranias are easily identified, for they are Fig. 215. Productus horridus (Permian, limestone). * FOSSIL LAMP-SHELLS. 231 found adhering like limpets, by the entire surface of the ventral valves, to other fossils. This family has had a wonderfully long range in geological time, for species belonging to it are not uncommon in the Silurian rocks, and the genus has lived on ever since into our own time, and is still to be found in British seas, particularly in the marine lochs of Western Scotland. The valves of Strophomena abundant in the Silurian rocks are semicircular in shape, and the two valves vary, being sometimes flat or concave or convex. It is the type of a family of Brachiopods to which the well-known genera Or this > Leptcena, Streptorhychus, etc., belong. The Productus family is a very important and a very interesting one. These fossils usually occur in great specific abundance, so that if we meet with one or two individuals we may expect to find others. Indeed, the living Brachiopods are still distinguished by their social or gregarious habits. Where they do occur, they live in abundance. One of the pleasantest rewards of the dredger in Oban Bay and there- abouts is to bring up a clinker with half a dozen living Terebratulina caput-serpentis. What a sensa- tion it is to see in the flesh a representative of one of the oldest and most continuously unbroken families of the globe ! It is like raising a ghost unawares. One of the best-known of living Bra- chiopods is the Australian WaldheimiaAustralis. We 232 OUR COMMON BRITISH FOSSILS. see it in every museum, and in most private col- lections ; and it can be bought very cheaply, which is perhaps a still better proof of its commonness. This Brachiopod can be gathered by handsfull in the reefs of the Australian coasts. Evidently, in the "good old times " (which must be the last lingering memory of the Brachiopods), this habit of living together not only characterized the race, but had very important geological results. Who can visit the bold Eglwysey rocks, in the Vale of Llangollen, for instance, and see how the white limestone is in places composed entirely of the valves Productus Llangolliensis, with- out feeling that if it had not been for the abundance and gregarious habits of this Brachiopod in the early Carboniferous seas, those very rocks would never have been in existence ? The same may be said of the Carboniferous limestone near Buxton, where the huge Productus giganteus not unfrequently as large as a child's head builds up the rock wholesale. Rhynchonella Wilsonii in the Silurian limestones, and Rhynchonella socialis (deservedly so called) in the Oolites, have performed the same geological feat. The Productidce are very easy to make out, not- withstanding their strong specific differentiations. The two shells are either concavo-convex, as in Productus giganteus y P. Martini, P. cora y etc., or round above and flat beneath, as in Productus punctatus, etc. The valves are, moreover, frequently adorned with spines, as in Productus spinosus (armed with them like a FOSSIL LAMP-SHELLS. 233 conchological hedgehog), or the well-known Pro- ducttis horridus of the Permian rocks the latter found in good condition near Tynemouth. Another feature about the valves of the Productus family is that they are " auriculated," which means that the shells are more or less drawn out on either side of the hinge-line. The Productida have been extinct ever since the close of the Primary or Palaeozoic epoch. A microscopical examination of the shells of any species of Productus would alone enable a student to identify it, if only on account of the peculiar " canals " which are present. Speaking of this group of fossils, Mr. Etheridge says "The significance or importance of Productus as a Carboniferous genus cannot be overlooked when determining, through its species, definite horizons in these rocks. It is ubiquitous ; in no region on the globe, where Carboniferous rocks are developed, do we not find this characteristic shell, and in vast abundance in the Polar regions, Australia, New Zealand, Van Dieman's Land, India, America (in fifteen states), throughout Europe, and in Africa." The space in the hinge-line between the two shells (deltidium) has to be taken into account in the endeavour to identify species. This is largest developed in Spirifera deltoidea of the Car- boniferous limestone and is not an uncommon fossil at Castleton, in the Peak District of Derbyshire, surely, one of the most delightful for a young 234 OUR COMMON BRITISH FOSSILS. geologist to " break ground " on, to be found within the narrow circle of the present British seas. Tcrebratulida is a well-known group of fossil Brachiopods, which have been in existence from the Devonian period without losing their distinctive cha- racters up to the present day. The genus reached its climax during the Oolitic period, when nearly seventy species were in existence. Waldheimia Australis the antipodal representative seems to be doing well and flourishing yet, as though the country which is still the abode of Marsupials (the low-pressure Fig. ziG.Terebratula biplicata (Oolite). Secondary type of Mammalian life that preceded the high-pressure forms of the Tertiary and Recent periods) were a belated geological area both as regards sea and land. What an abundance of species of Terebratula occur in the limestone of all the geolo- gical periods ! Terebratula hastata swarms in many localities in the Carboniferous limestone. About Castleton, Derbyshire, and near Clitheroe, Lanca- shire, we get it in every stage of growth, and with remnants of its ancient radiating colour-bands still FOSSIL LAMP-SHELLS. 235 adorning it. The noble Pentamems Knightii of the Aymestry limestone used to be so abundant that it was used to mend the roads with. Terebratula sella is no less abundant in the Oolite ; T. carnea and T. globosa, equally so in the White Chalk of England, in almost every Chalk-pit. T. grandis, of the Suffolk White Coralline Crag,, is the hugest and finest of all, but uncommon enough for the young geologist to be Fig. 217. Diagram showing the various stages of development in a recent Brachiopod, from b, c, larval stages, etc,, to a, adult animal. delighted when he finds a specimen with both valves still united. The fossil Brachiopoda have undergone great changes. In the Cambrian, Silurian, and Devonian slates we find them chiefly as casts, the fossils being natural casts of the interior of the shells, and the slates retaining the impressions of the external ribs and other markings. On the top of Snowdon, and elsewhere, we find them imbedded in volcanic ashes. 2 3 6 OUR COMMON BRITISH FOSSILS. which accumulated on the ancient Silurian sea- bed. The original lime of the shells has in all these instances been dissolved away by the action of perco- lating water. The Upper Silurian rocks, limestones, and shales are perhaps the best hunting-grounds for fossil Brachiopoda. More than a hundred species are found Fig. *&. Terebratula deformis. Fig. 219. Terebratula lyra. Fig. 220. Terebratula dorsata (showing interior). in them, and there is not a single locality where these rocks are quarried (that I know of) where fossil Brachiopoda cannot be obtained. Some districts are especially noted for them the Wren's Nest, near Dudley; Aymestry; Woolhope; the Malverns ; Girvan, in Ayrshire, etc. They are not less common in the Devonian and Carboniferous limestones as regards FOSSIL LAMP-SHELLS. 237 individuals. The most notable form in the Devonian rocks is Calceola, which occurs in such numbers near Torquay and Newton that the rocks are technically called " Calceola-beds." Every geological formation, Fig. 221. Terebratula, one valve showing large internal loop. and most subdivisions, have their suite of peculiar Brachiopods. The coins of the later Roman empire do not succeed each other more rapidly than do these Fig. 223. Teretratula caput-serpentis (recent, -^vv-^Bf- k u t supposed to be Fig. 222. Recent species identical with T. striata. Fig. zz^.Terebratula dr- of Terebratula. of the Chalk). sata (exterior). fossils in the rocks of Palaeozoic age. Hence their great value to the geologist in helping him to diagnose the strata where he happens to find them. Another peculiarity about the Palaeozoic Brachiopods is their 238 OUR COMMON BRITISH FOSSILS. world-wide character many of the same species dis- tinguish Australian and American limestones and shales which are characteristic of British rocks. Alto- gether this is a most interesting series of animal forms, and one which has played no small share in the formation of the stratified rocks of the earth's crust living on through long periods of geological time ; silent witnesses of those great world-throes and world-changes, each appearing at the time destructive, but all of which were combined to make our world such as we find it to-day. C 239 ) CHAPTER X. FOSSIL MOLLUSCA (PALAEOZOIC, OR PRIMARY). BIVALVES AND UNIVALVES. IT does not need much mental preparation to per- ceive that the hard parts of those animals popularly called " shell-fish " must have contributed very largely to " fossil remains." They are so abundant, so widely spread, so wonderfully adapted to almost every phy- sical condition of the earth's surface terrestrial, fresh- water, brackish water, shallow and deep seas, to cold, temperate, and tropical regions alike that it is not surprising the geologist pays great attention to the suggestions which fossil mollusca give him. More- over, mollusca are, perhaps, among the most perma- nent and stereotyped, and the least inclined to change of animal forms. The fossil fresh-water mussels which flourished in the extensive lakes of the Old Red Sandstone period (Anodonta Jukesii] do not differ in any important character from the Swan mussels (Anodori)) so abundant in English lakes and rivers at the present time ; the Palndina of the Wealden epoch, 2 4 o OUR COMMON BRITISH FOSSILS. and the Planorbis of the Eocene, are so like species of the same genera now abundant in any of our streams and ponds, that the least informed student would identify the relationship at once. Perhaps this wonderful persistence of type in fresh-water mollusca is to be found in the fact that fresh-water conditions experience less change in phy- sical environment than any other. The water of the Old Red Sandstone lakes may have been exposed Fig. 225. Orthonota parallela. Fig. 226. Murchisonia. gracilis. to warmer conditions than those of Great Britain now, but in the deeper parts the bivalve mollusca would find almost similar conditions that modern fresh-water bivalves would be able to select, if they chose to do so. The composition of the shells of bivalve mollusca is not always the same. Indeed, we may somewhat definitely separate them into two classes, according to the chemical composition of their shells calcitic FOSSIL MOLL USCA J8IVAL VES AND UNIVAL VES. 24 i and arragonitic. To the modern student of mollusca this may not seem of the same importance it is to the geologist. To the latter, this difference in the compo- sition of the limy shells of bivalves is frequently of great value : for the valves composed of the limy mineral arragonite are liable to be decomposed by the action of percolating water through the rocks in which they are imbedded much sooner than those constructed of calcite. Hence the geological student finds the remains of fossil mollusca possessed of shells composed of arragonite chiefly, if not entirely, as casts. Calcite is a more stable or endurable form of lime than arragonite hence the reason why mollusca whose shells are formed of arragonite are found as casts, whilst those whose shells are of calcite appear to be unchanged. Shells are useful to the geologist, also, in quietly but emphatically convincing him of the former con- ditions of marine and fresh-water deposition of strata. He finds them bored by marine sponges. Or they may be covered, inside and out, with the tubes of marine worms or Polyzoa, or spat of ancient oysters in which case he knows these fossil bivalves died, and their parts separated, before the contemporary creatures which made use of them for a mechanical foothold could spread there. Such conditions quite correspond to those he sees going on nowadays at the seaside. Bivalves and univalves are the most abundant of R 242 OUR COMMON BRITISH FOSSILS. the mollusca, and their hard parts or shells are among the most valuable and durable of all the " medals of creation." But doubtless there were sea-slugs in the ancient seas, just as there are now, but as they possess no hard parts (except teeth), they have not contri- buted in any notable way to fossil remains. When we study the fossil mollusca, we see that the univalves have been more modified than the bivalves. Mr. J. Starkie Gardner has also noticed this fact. He states that, as regards bivalve mollusca, there does not seem to be any broad rule of progression. The contrary is the case with the univalves or Gasteropods. In them, says Mr. Gardner, there is a most unmistakable and pronounced tendency to elongate the canal. He therefore thinks that the presence in greater or less numbers, or the absence, of spindle-shaped or fusi- form shells possessed of lengthened canals, would be an infallible test of the geological age of any group of Gasteropods, from the Oolitic rocks to the Eocene. Thus, the Cones and the Cowries are among the most highly differentiated of Gasteropods, and they are also the latest introduced. The mollusca have a geological value in deter- mining the physical conditions of ancient seas. Where bivalves abound, as in the different strata of the Oolite, we have evidence of shallow water, and this is usually supplemented by other facts. Not unfrequently the univalves bear similar testimony, for many littoral or shallow-water genera have a very high geological antiquity. FOSSIL MOLLUSCA BIVALVES AND UNIVALVES. 243 One broad fact also strikes the geological student : the specific and numerical abundance of mollusca, bivalve and univalve, is greatest in the most recent formations, and least in the oldest ; whereas the specific and numerical abundance of the Brachiopods is just the reverse greatest in the oldest deposits, and scan- tiest in the latest formed. The shells of bivalves may be regarded as hollow cones. The umbo or beak is the apex of such cone. The shells are frequently unequal-sided, one being more elongated than the other. The mouth of the animal within the shell is uniformly on that side of the body indicated by the umbo or beak ; hence this is called the anterior or front part of the shell. The two valves are hinged together by projections and notches which accurately fit each other, and these are technically called " teeth." Their number, size, and position have to be carefully noted, for they are among the chief means of diagnozing genera and species. Inside the shells of all bivalves, fossil as well as recent, the student will observe well-defined scars, which indicate where the mantle of the animal was attached. In some mollusca the mantle is in two halves or lobes which are united along their edges, so that a siphon is necessary to admit water to the gills. Such bivalve mollusca are usually sand and mud dwellers, and during life are imbedded in an upright position, with the siphon projecting above the muddy 244 OUR COMMON BRITISH FOSSILS. bottom where they are protected. These siphons can be lengthened or shortened at the will of the animal, by means of special muscles. These muscles leave their marks on the interior of the shell, so that a naturalist can readily tell a Siphonate mollusc from an Asiphonate kind. In the latter, the scar left by the mantle's attachment is unbroken ; in the former, it is indented into a sort of bay or sinus. Scars are also left by the adductor muscles, which close the two shells and defend the animal from enemies. Singularly enough, there is a geological peculiarity about the two kinds of bivalves just mentioned. Fig. 227. Cardiola. interrufita. (Silurian). Fig. 228. Pterinea subfalcata (Silurian). The siphon-bearing (Siphonate] mollusca get more numerous in the Secondary rocks than they were in the Primary, whilst they are far more numerous in the Tertiary strata than in the Secondary. The Primary and early Secondary rocks are marked by a preponderance of siphonless (Asiphonate} bivalves. Fossil bivalves first make their appearance in the 'Lower Tremadoc rocks, where about twelve species have been found. The univalves first appear in the Arenig rocks. In the neighbourhood of St. David's FOSSIL MOLLUSC A BIVALVES AND UNIVALVES. 245 four genera are met with, among which are the ancient forms of Pleiirotomaria and Euomphalus. But neither bivalves nor univalves are very abun- dant in our British Cambrian rocks. Perhaps the district of Ty-Obry, North Wales, is one of the best for rinding this class of fossils, among which are Palcearca socialis, and species of Ctenodonta. These are, in reality, very highly organized bivalves, and the fact that they are among the oldest known indicates, Fig " >*-***>*'* *<- if evolution be true, that many other simpler forms must have preceded them. In the Silurian rocks the true mollusca grow more abundant ; and in the Upper Silurian, although there are few species, these are individually abundant. Both in the Cambrian and Silurian rocks (except in the limestones of the latter) the fossils exist as casts. The lime of the true shells has long been dissolved away, and only the impressions left in the rocks where they were originally imbedded. These im- pressions have often been filled in by infiltration of some other material, so that natural casts of them have thus been taken. Nevertheless, vast numbers of the fossils in these older rocks are only to be met with as impressions. Many of them are very clear and beautiful ; others are not only obscure, but often pulled out of shape by having partaken in the mole- cular movements resulting in " cleavage." 246 OUR COMMON BRITISH FOSSILS. The most abundant of these early genera of mollusca, besides those already named, are Patella (the limpet, whose simple cone is an index of the degree in which all univalve shells have been modi- fied), Bellerophon (a " heteropod," or free-swimming gasteropod), Natica (which has been in existence ever since, and is still abundant in British seas), Mur- chisonia, Holopella, Loxonema, Cyclonema, Ophileta, Orthonota, Ambonychia, Pterinea, Myacites, Cardiola, Nuclea, etc. In the Middle Silurian rocks which crop up about Eastnor, in the Malverns (a locality not likely to be soon forgotten for its quiet beauty), one bivalve, Niiclea Eastnori, is common. Several small quarries may be visited in Eastnor Park where these fossils are to be obtained. Near Bronsil a large species of Pterinea occurs. The Upper Silurian rocks almost everywhere yield plenty of fossil mollusca. In the hardened Wenlock shales about Llangollen, Cardiola interrupts is most abundant ; the casts showing that the two opened valves were not separated. The Ludlow beds in the quarry on the side of the river opposite the picturesque old castle, are crowded with Ctenodonta and Orthonota. In the Wenlock limestone of Shropshire and South Staffordshire that splendid fossil univalve Euomphalus rugosus is abundant. The Middle Devonian strata of North Devon occur in about the most varied and picturesque portion of that charming county. I have found a FOSSIL MOLLUSC A BIVALVES AND UNIVALVES. 247 little botany an excellent help-meet to fossil-hunting, for they can both be pursued together. Nowhere is this twofold pursuit more delightful than along the coasts of North Devon. At the Little Hangman, the rocks in places are fossiliferous, although only to be met with as casts. Here is that singular and easily recognized bivalve Megalodon, and large mussel Natica, etc. The quarry at Hagginton Hill abounds with fossils, and the pedestrian will frequently meet with them as he hammers his way along from Ilfra- combe to Combe Martin. At Pilton and Barnstaple the Upper Devonian rocks yield abundance of Avicula, Ciicculea, Modiola, etc. Perhaps the richest locality for obtaining these are the rocks on the summit of the hill at Baggy Point : Braunton, Marwood, and other localities, also yield them. Top Orchard quarry has long been a recognized Devonian hunting-ground. The Devonian limestone also contains fossil mol- lusca. The ancestors of the common cockle (Car- diuiri] first appear here. Loxonema Murchisonia, etc., are found in the limestone at Plymouth, Chudleigh, Newton Abbot, and elsewhere. Fossil fresh-water mussels, nearly allied to the common swan mussels of our rivers, are in abundance in the Old Red Strata of Kiltorcan, in Ireland. The species (Anodonta Jiikesii) was named after the late director of the Irish geological survey. This fossil bivalve is also found in strata of similar age in Scotland. 2 4 8 OUR COMMON BRITISH FOSSILS. The Carboniferous formation, in all its divisions, contains plenty of fossil mollusca. In places these are overwhelmingly abundant. The limestone yields several species of Natica. At Castleton, in the Peak Fig. 230. Better o^hon hiulcus (Carboniferous limestone). of Derbyshire, these fossils are very beautifully pre- served, and often of large size. The largest species, however, is to be met with in the neighbourhood of Fig. 231. Posidonia. (Carboniferous). Clitheroe, in Lancashire, associated with Bellerophon. Both are met with as solid casts, often besprinkled with small crystals of calcite ; and the geologist will FOSSIL MOLL USC A BIVALVES AND UNIVALVES. 249 see them ornamenting the window-sills of the cottages, or conspicuously placed in the " rockeries " of the gar- dens. Euomphalus pentangulatus is another abundant Carboniferous univalve, and one of the most beautiful. Fig. 232. Antkracosia robasta. It is very easily hammered out of the rock, where its hollow coil leaves a pretty impression. At Castleton it is extremely abundant, and may be met with in every stage of development ; but, in point of fact, it is one of the most abundant and cha- racteristic of the Carboniferous limestone fossils. Pleurotomaria carinata is abundant in places, as at Castleton one of the best localities in Great Britain for the exquisite state in which the fossils are preserved. I have met with Pleurotomaria there with the zigzag markings still quite distinct. Capulus or Calyptrea, Naticopsis, Murchisonia, Solarium, Nerita, Posidonomya, San- guiiiolites, Pinna, Pecten, Cardiomorpha, etc., are not unfrequent. In the black Carboniferous limestone Fig. 233. Pleurotomaria carinata (Carboniferous limestone). 250 OUR COMMON BRITISH FOSSILS. of the Isle of Man Sanguinolites is locally very plentiful. The Yoredale shales, and also the true Lower Coal Measures, often contain an abundance of fossil marine mollusca. Of these Posidonomya and Aviculo- pecten papyraceus are most numerous. The former is a small, thin bivalve ; the latter of much larger size. In the black shales which crop out in the gorges and valleys near Hebden Bridge and Tod- Fig. 234. Aviculo-pecten papyraceus Fig. 235. Euomphalus pentangulata (Carboniferous formation). (Carboniferous limestone). morden, Aviculo-pecten is converted into iron-pyrites, and the black shales look as if they had been gilded all over with pictures of this fossil. In the shales of the coal-seams in the Lower Measures near Oldham, and also in a similar situation in strata of about the same age at Halifax, Aviculo-pecten is un- compressed, and usually converted into carbonate of iron ore. This fossil is quite as abundant in the shales of this age in Ireland as in England. At the FOSSIL MOLLUSCA BIVALVES AND UNIVALVES. 251 pretty spa of Lisdoonvarna, county Clare, it crowds them everywhere and the chemical decomposition of the pyrites, these fossils were originally converted into, has probably originated the sulphur springs. Fresh-water mollusca take the place of the marine forms in the Upper Coal Measures. The most abun- dant is the genus Anthracosia^ or " fossil mussel." Its dark-brown shells, often much flattened and crushed, may be found in the greatest abundance on the shale- heaps which accumulate near the coal-pits in Lan- cashire, Cheshire, and Yorkshire. In the colleries near Wigan several species may be obtained ; one kind, A. robusta, so named on account of its greater size, is most abundant about the pits where the " Arley mine" is worked for coal. These Anthracosia are sometimes so numerous that the surfaces of the shale are completely covered thereby. Not unfre- quently they are converted into argillaceous iron ore, and can then be picked out of the soft shale like nuts. At times they form bands of ironstone, rich enough to be worked and smelted, as at Carron, in Scotland, where the celebrated " Blackband " ironstone is formed of nothing but minerally altered mussel-shells. The geological student can hardly go to a coal-pit in Lancashire and Yorkshire, especially in the neigh- bourhoods of Manchester and Barnsley, without finding plenty of Anthracosia. The Permian rocks of England are nowhere par- ticularly rich in fossils except, perhaps, a few localities 252 OUR COMMON BRITISH FOSSILS. near Tynemouth, where nests of minute Rissoa-like univalves are found. Bakevellia and Schizodus are the characteristic bivalves. The former used to be met with in great abundance in the Permian marls at Collyhurst, Manchester, but the place is now com- pletely built over. The best Permian fossil-bearing localities are in Durham. About one-half of the fossil animals found in the Permian strata of Great Britain are mollusca, which fact is a fair index to the comparatively rapid manner this group had deve- loped since its first scanty representation in the Cam- brian formation. Some important genera first appear in the Permian, most notable among which, perhaps, is the genus Mytilus, or the true mussel family. C 253 CHAPTER XL FOSSIL MOLLUSCA (MESOZOIC, OR SECONDARY). FOSSIL mollusca increase very rapidly, both in species and numbers, as we explore the strata of the Secondary formations. They are absent from the Trias of Great Britain, the greater part of whose beds seem to have been formed along the bottoms of large lakes, something like the existing Dead Sea, whose waters were too salt for Mollusca to live in. In the Rhaetic beds, however, which overlie the upper Trias, and which seem to have been formed under semi- marine or brackish-water conditions, bivalves are very abundant, and some of them are quite characteristic, such as Cardium Rhaticum, Pecten Valoniensis, Avi- cula contorta, Ostrea liassica. The student will find them in any quantity in the rocks forming the bold headland of Penarth, just beyond Cardiff, and also at Aust Cliff, on the opposite side the Severn estuary to Chepstow. At the latter place the grey Rhaetic strata succeed the red Trias, and the ground is strewn with fallen blocks of the former, where some splendid 254 OUR COMMON BRITISH FOSSILS. fossilizing may be had bones, teeth, and spines of fish, saurians, etc., as well as fossil shells being abun- dant. It is in this formation (a part of which was formerly known as the " White Lias ") that the well- known but curious " Landscape marble " occurs at Gotham. Practically, we may say that the Rhsetic series extends diagonally across England, from Red- car, on the north Yorkshire coast, to Lyme Regis. In many places its beds have been exposed, as near Leicester, where shells may be got. Somersetshire, however, is perhaps the best county for specimens, those obtained from near Watchet having found their way into most collections. Among other localities where Rhaetic fossils can be hammered out are Queen Camel, near Yeovil, Westbury, Puriton, Shepton Mallet, Wedmore, and Beer Crocombe. The strata of the Lias frequently teem with fine and well-preserved specimens of fossil mollusca, so that it is both difficult and tedious to enumerate localities for finding them, either in this formation or the Oolite, of which the Lias is now usually re- garded as the lowest member. A good many modern genera of mollusca first make their appearance here, such as Corbis, Astarte, Limncea, Lithodomus, and Teredo. The last two are curious on account of their habits, Lithodomus being a burrower, and Teredo (the genus of modern "ship-worms") a borer into wood, etc. In the Oolite proper the now widespread genus FOSSIL MOLLUSCA. 255 of bivalves, Venus, commenced its existence, together with Trigonia (still surviving in Australian seas), . Isocardia, Tellina, Corbula, Panopcea, Bulla, Paludina, etc., all of which are well-known modern forms. The naturalist is as much interested, when studying the life-history of the globe as revealed by geology, in observing where the different kinds of families of animals and plants first make their appearance, as a genealogist is in tracing the commence- ment, development, and alliances of some illus- trious aristocratic houses. Commonest among the genera of Liassic and Oolitic univalve and bi- Fig " i*-**** >*" ( olite >- valve mollusca are (in addition to those above-men- tioned) Purpurina, Cerithium, Nerinea, Apporhais, Potamides, Modiola, Ostrea, Gryphoea, Exogyra, Ger- villea, Pholadomya, Anatina, Lima, Hippodium y Pecten, Cucullcea, Avicttla, etc. Some of these are splendid fossils ; and there are few cabinets, and perhaps no museums, which do not possess Lima gigantea, Avicula Cygnipes, Hippodium ponderosum, Trigonia clavellata, etc. If the student cannot afford to travel in search of specimens to the spots where they are actually found, he can obtain them nowadays by various means, in 2 5 6 OUR COMMON BRITISH- FOSSILS. exchange for those of his own neighbourhood. Or let him cultivate the acquaintance of the nearest stone-mason's yard, the proprietor whereof will set him up with plenty of "rotten stuff," unworkable because of the hollows and casts of fossil shells, but dearer to the young geologist than a gold-mine on that account ! Fragments of Portland Oolite may always be got in any large stone-mason's yard, and they contain an abundance of fossil (casts), Nerincza, Cerithium, and Trigonia, all of which are usually casts Fig. 237. Trigonia margaritacea (Australia seas). of the interiors of these shells ; so they have a very different appearance from the more gracefully shaped and ornamented exteriors. Tourists in the north-west of Scotland will find some interesting and varied geologizing in Western Scotland and the Hebrides; and in various places the Lias beds yield fossils, as along the Sound of Mull, Tobermory, the Isle of Skye, Eigg, Muck, etc., where there are fragmentary patches and outliers of once very extensive Lias and Oolitic strata, which probably extended from continuous fossilferous strata. FOSSIL MOLLUSC A. 257 In Northamptonshire numerous fossil mollusca can be collected in the refuse of the iron-mines near Northampton town, and also at Kingsthorpe, Durton, and Blisworth. No fewer than one hundred and twenty-five species have been catalogued from the last neighbourhood. The " Northampton Sands " are very rich in this class of fossils, having yielded one hundred and forty-one species of bivalves, and thirty species of univalves. The Oolitic strata of Yorkshire will similarly Fig. 238. GrypJuza incurva (Oolite). reward the student, and these are all easily accessible from the various watering-places, such as Scarborough, Whitby, and Filey. Among other localities which are richly fossiliferous are Cloughton Wyke, Hundale Hayburn Wyke, Gristhorpe, Cayton Bey, Pickering. In Lincolnshire the Oolitic beds are cut through by the railway from Spalding to Lincoln, and in proceeding to the latter place from Grantham we S 2 5 8 OUR COMMON BRITISH FOSSILS. see them forming the hills which flank the railway on the right-hand side. Numerous quarries, for road- material, limestone, and ironstone, are opened in them, where plenty of fossil mollusca can be collected. Perhaps the best collecting-grounds for Oolitic fossils in Lincolnshire are at Weldon, Wakerley, the neigh- bourhood of Stamford (as at Squire's Stone quarry), Wild's Ford, Kingscliffe, Stibbington, Whittering, Wrawly, Brigg, Market Rasen, and Horncastle. We naturally turn to the West of England, how- Fig. v$9.Gervtllec ever, for Oolitic fossils. The great Oolite formation extends from the middle of Lincolnshire to Gloucester- shire, and quarries for various purposes are opened in it more or less along its entire course, where fossils abound, among which bivalves and univalves are the most numerous. There are also plenty of places in Bedfordshire (as in Cowper's county), Rutland- shire, Buckinghamshire, and Oxfordshire, as well as Gloucestershire (which last county is nothing if not Oolitic),, Somersetshire, Wiltshire, Dorsetshire, etc. FOSSIL MOLLUSC A. 259 Mr. Robert Damon's excellent book on the geology of the latter coast supplies the tourist with more good fossiliferous localities than he will have time to visit, unless he has got nothing else to do, and both time and means to indulge his fossil-hunting propensities. Of course, all the strata at Kimmeridge Bay are classic ground for their geological interest. Both here and the neighbourhood of Weymouth fossil mollusca abound, Trigonicz being particularly plentiful Fig. 240. Plafostom Gigante-um (Lias). at Weymouth, Osmington. At Sandsfoot Castle we get the great Ltmas, and at High worth. At Port- land these fossils are so plentiful that one stratum of Trigonia gibbosa goes by the name of the Trigonia bed. The same series contains a stratum crowded with another fossil bivalve, Exogyra bruntrutana. Between Swanage and Bridport the geologist gradually passes from the Eocene, through the Cre- taceous, down to the lower strata of the Oolite. The 260 OUR COMMON BRITISH FOSSILS. Fuller's earth at Langton, five miles west of Wey- mouth, contains plenty of small elongated fossil oysters, Ostrea acuminata. The Forest marble of the neighbourhood yields Avicula, Lima, Pholadomya, Pec ten, Trigonia, Myacites, Turbos, Eulimas, etc. In the quarry at Well Down, Ostrea Sowerbyi and Avicula costata are especially common. The stony cliffs of the back-water channel near the village of Radipole are com- posed of Cornbrash, crowded with bivalves and univalves, the com- monest being Pholadomya bu- cardium and Avicula edimata. There are numerous quarries in the neighbourhood where similar fossils may be obtained. The beautiful Vale of War- dour, Wiltshire, has long been famous for its yield of Oolitic fossils, and the geological structure of the district has been described in the "Transactions of the Geologists' Association." Among the commonest of the fossils belonging to the classes we are now considering are Cerithium Portlandicum, and other species of this genus of univalves ; several species of Trigonia, Ostrea, Cardium dissimile, etc. The neigh- bourhood of Swindon is richly fossiliferous, Trigonia, Lima, Ostrea, and Perna being very common. The Upper Oolites continue into Buckinghamshire, where Fig. 241. Hippopodium ponderosum (Oolite). FOSSIL MOLLUSC A. 261 the limestones are usually full of fossils, such as Natica, Trigonia, Cyprina, Cypricardia, Pleuromya, Mytilus, etc. Mr. Etheridge, F.R.S., states that the Oolitic (or Jurassic) rocks of Great Britain have yielded up to the present time no fewer than ninety-five genera, and one thousand three hundred and sixty-eight species of fossil bivalves alone. Indeed, they are by far the most abundant forms of ancient life met with in these rocks, although both Ammonites and Belemnites, and, in some localities, even Brachiopods, are also very numerously represented ; some species of Avicula, Hinnites, Lima, Ostrea, Pecten, Perna, Pinna, Astarte, Trigonia, Modiola, Cucculcea, Pholadomya, etc., have a very long upward range. The total number of the Oolitic Gasteropods (according to the same high authority) is seventy-six genera, and one thousand and fifteen species. The most numerously represented of these genera are Alaria, Cerithium, Chemnitzia, Nerincea, Pleurotomaria, Trochns, and Turbo. In the uppermost strata of the Oolitic formation are the fresh-water beds at Purbeck, so crowded with the still living Paludina as to constitute the famous "Purbeck marble," formerly used in interior church work. Associated with this univalve are Planorbis, Melania, Limncea, Physa, Cyclus, Corbula, and other well-known recent genera. Lulworth Cove is a capital hunting-ground for them. The Wealden Clay, Sussex, has in places beds of 262 OUR COMMON BRITISH FOSSILS. so-called " Sussex marble," also formed chiefly of a species of Paludina, which can hardly be distinguished from that which still abounds in English rivers. In the Isle of Wight the Wealden is also fossiliferous, especially near Sandown, the commonest fossil being a fresh-water bivalve Unio Valdensis. At Punfield, in Dorsetshire, fresh-water shells, such as Cyrena, Cyclas, Unio, etc., are mixed with oyster-shells, indicating brackish-water conditions. The Cretaceous, or Chalk formation, includes the Neocomian (better known, perhaps, as Lower Green- sand), the Gault and Upper Greensand, and the Upper or Grey and White Chalk beds. At Speeton and Tealby, in Lincolnshire, there is a bed of clay five hundred feet thick belonging to the former sub- division, and this is remarkable for a very large bivalve, Pecten cinctus, which is sometimes as much as a foot in diameter ; Perna Mulletii is another characteristic fossil. The Lower Cretaceous beds are extensively developed in Surrey, Kent, Sussex, Oxfordshire, Bedfordshire, Hampshire, Wiltshire, Norfolk, etc. At Atherfield, in the Isle of Wight, the common fossils are Perna, Area, Astarte, Panopcea, Gervillea, Trigonia caudata, Exogyra sinuata, etc. Near Maidstone there are numerous fossiliferous localities ; the quarries where the well-known " Kentish rag " is worked are good fossiliferous places, where Exogyra and Trigonia more or less abound. Other localities are Godalming, Godstone, Folkestone, FOSSIL MOLLUSC A. 263 Wotton, Sevenoaks, Nutfield, Pulborough, and Peters- field. Near Folkestone there occur layers of a siliceous limestone often full of Ostrea, Area, Lima, Exogyra, Panopcea, and Pecten. At Shotover Hill, near Oxford, there are strata of this age which contain Unio, Cyrena, Paludina, and other fresh-water forms. In Bedfordshire (as, for instance, at Patton, Woburn, Ampthill, Sandy, Wicken, and Upware) the sands are worked in order to get at a " coprolite " bed, which is frequently as much as two feet thick. These " coprolite " workings Fig. 242. Inoceramus sulcatus (Gault). are capital places for fossils, all phosphatized, or converted into phosphate of lime, and most of them of considerable interest and importance, because they have been "derived" or washed out of the older formations where they were originally deposited, such as the various strata of the Oolite and Wealden. Ostrea, Gervillea, Exogyra, Gryphcea, etc., are very common. The fossils of the Gault have always been admired on account of their great beauty ; many of them still 264 OUR COMAION BRITISH FOSSILS. retain, when dug out of the stiff clay, the rainbow hues of the nacre or mother-of-pearl coating. But the shells are fragile, and the tints evanescent, unless means are taken to preserve them. The commonest of the bivalve and univalve fossils are Inoceramus sulcatuSy Plicatula, Dentalium y Rostellaria, etc. Out- crops of Gault clay, containing fossils, are worked at Barnwell, near Cambridge, but the chief hunting- ground has long been Copt Point, Folkestone, which is classic on that account. In Norfolk, the Red Chalk of Hunstan- ton which stands forth in such vivid relief from the green strata below and the grey chalk above it is usually regarded as of the same age as the Gault. It is in places full of small Belemnites, like those obtained from the Gault, and contains (Lower Chalk). numerous Inocerami and Ostrea. The Greensand of Cambridge rests on the Gault, and is crowded with fossils which have been washed out of that deposit. The Upper Greensand occurs in Devon, Somerset, Sussex, Kent, Isle of Wight, Dorsetshire, etc. Its chief fossils are Pecten FOSSIL MOLLUSC A. 26 : asper, Pecten Beaveri, Pecten quinquecostatus, Exogyra cotiica, Ostrea carinata. The Warminster and Black- down beds are also well known collecting-grounds for fossils of this period. Fig. z^.Fecten Beaveri (Greensand). The Upper Chalk strata are always favourite fossil-collecting beds to a young geologist. The fossils look so pretty, when properly cleaned, in their white matrix ; and, moreover, the eyes of the ardent youth are not so likely to be fatigued or repelled by 266 OUR COMMON BRITISH FOSSILS. the glaring whiteness of the chalk quarries in the hot summer sunshine, as they will be in later life. In Kent, Sussex, Dorset, Suffolk, Norfolk, Lincolnshire, Hertfordshire, etc., as well as the North of Ireland, every Chalk-pit contains fossils, more or less. True, both bivalves and univalves are comparatively rare, for these indicate that the strata they are found in were deposited in shallow water, whereas all the fossils incident in the Chalk, and especially in the Upper Chalk, bespeak deep water. Perhaps the earlier Fig. 245. Pecten orbicularis (Chalk). geologists thought the White Chalk was originally formed in deeper water than it is now known to have been ; but it must still be regarded as a deep-sea deposit, in comparison with the varying strata of the Oolite. The Lower White Chalk, perhaps, contains more fossil bivalves than the Upper. Some of them attain a large size, such as Inoceramus Cuvieri and Inoceramus Lamarcki) whose vertically fibrous structure reveals to the student the presence of the smallest fragment. FOSSIL MOLLUSC A. 267 Inoceramus sulcatus and Inoceramus concentricus are also abundant forms, and they often serve to distin- guish a block of Lower White Chalk from the Upper, where they are either uncommon or absent. In the Chalk one of the commonest and most beautiful fossils is the bivalve Spondylus spinosa, which Fig. 246. Pecten interstriatus (Greensand). also rejoices in the other names of Plagiostoma spinosa and Lima spinosa, much to the unnecessary bewilder- ment of the student. It is difficult to extract it with its long spines intact, but patience, and the fortunate softness of the moist chalk when the fossil is first extracted, as well as the clever use of a camel's-hair 268 OUR COMMON BRITISH FOSSILS. brush to laboriously wash away the chalk matrix, will bring the collector off triumphantly. Ostrea ves- cicularis is a very abundant fossil in the Upper Chalk. It is found in every stage of development, from the young spat no bigger than a pin's head, to a grotesque and many-layered old Ostrea. One learns a good deal of the conditions of the deep sea- bed where chalk was formed, from such fossils as O. vescicu- laris. I know of no other fossil so apt to bewilder the young geologist, for Fig. 247Pecten inequvisival its external shapCS ai'C (Greensand). various. The fact is, it could find few or no solid objects amid the slimy, Fig. 248. - Pecten asper (Greensand). FOSSIL MOLL USC A. 269 muddy ooze (now white chalk) of the Cretaceous sea-bed, to which its valves could be attached. It Fig. z^o.Turitella Fig. 249. Z?/ac0ra J^rzata (Cretaceous), granulata (Greensand). was thankful to settle down as spat on any surface Fig. 252. Chama squamosa (Lower Fig. 251. Spondylus spinosus. Cretaceous). Fig- 253- Gervillea anceps (Greensand). which presented itself whether a dead "fairy-loaf," the bone of a decomposed cuttle-fish (Belemnite), the 270 OUR COMMON BRITISH FOSSILS. dead shell of an Ammonite, etc. where it settled, there it grew, adapting its expanding shell to the object it Fig. 254. Ostrea vescicularis Fig. 255. Cardium Lil- Fig. 256. Exogyra. (Chalk) lam tin (Greensand). conica (Greensand). was attached to ; and so in the Chalk-pits near Nor- wich we find this very common fossil more than half Fig. 257- Pecten quadri- Fig. 258. Inoceramus costatus. concentricus. encircling the solid shafts of Be- lemnites, or actually taking the impression of some coiled Am- monite Other bivalve mollusca of the Chalk are the grace- ful Inoceramus mytiloides and /. labiatus, the latter not unfrequent near Dover, whilst the former is found generally in the Lower White Chalk. ^ a Parkinsonii. ( 27 1 CHAPTER XII. FOSSIL MOLLUSCA (CAINOZOIC, OR TERTIARY). NOWHERE is a knowledge of fossil bivalves and uni- valves of such great importance as in the Tertiary strata. All other kinds of fossils are few in compari- son with their abundance. The pursuit of Tertiary geology takes the student into some of the most delightful spots in southern and eastern England, and to wide stretches of heath and common which still remain unenclosed. The sandy nature of the strata of many Tertiary formations tends to a " hungriness " of surface soil, especially in districts south of the Thames, where the morainic matter, or Boulder-clay of the Glacial period, is not strewn over the older deposits. In Dorsetshire and Hampshire the Lower and Middle Eocene beds are frequently rich in fossil plants (as in the clay-pits on the west side of Bournemouth). The vertical strata of " pipe-clays," with their beauti- 272 OUR COMMON BRITISH FOSSILS. fully preserved fossil plants, are also well known at Alum Bay, Isle of Wight The Thanet Sands may be seen resting on the Chalk in the large pit close by Charlton Station, near Woolwich, and some fine fossils characteristic of this deposit may be obtained there, such as Turritella, Cyprina, Aporrhairs, Corbula^ etc. The Woolwich and Reading beds are excavated into, or else they naturally crop out in various places about London, as at Woolwich, Blackheath, Reading, Fig. 260. Cyrena antiqua. etc. Banks of fossil oysters (Ostrea bellorvacina) are found ; Bromley being perhaps the best place to get them. Melania, Cyrena cuneiformis, and other mol- lusca, all of which indicate brackish-water conditions, are plentiful near Woolwich and New Charlton. These and other fossils are also found near Dulwich, Lewis- ham, and Peckham. The London Clay is of course the thickest and most important member of our English Eocene for- mation. Fossils, however, only occur in it here and there, and at different horizons. The Isle of Sheppey has long been famous as the best collecting-ground, FOSSIL MOLLUSC A. 273 but univalve and bivalve mollusca, such as Valuta nodosa, Pliorus extensus, Rostellaria ampla, Leda amygdaloides, Crypto don, etc., are found at Highgate. Some of these, and other fossils, are also met with near Hungerford, Basingstoke, Bognor, Finchley, Holloway, Ipswich, and Harwich ; especially in the cement stones, which, near Harwich and Ipswich, are often full of Modiola and Cyrena. The Harwich cement-stones are rich in fossil wood, showing structure when cut and polished ; and large fragments of this wood are often seen perforated and honey-combed by a species Fig. 261. Wood perforated by the tubes of Teredo. of the same kind of boring-mollusc (Teredo) as that which has earned for itself the modern name of " ship- worm." In the Suffolk crags, the bewildered student frequently finds contorted and serpentinely inter- twined masses, and he wonders what they are, little thinking they are the filled-up 7Vra&-borings in the fossil woods of the London Clay. The fossil wood was washed out of the latter deposit by denudation was then gradually dissolved away, so that eventually T 274 OUR COMMON BRITISH FOSSILS. the casts of the Teredo-borings alone were left to tell of the many changes through which re-deposited fossils frequently have to pass before they reach their final resting-place. Bracklesham Bay, in Sussex, has long been famous for its remarkable series of Eocene strata, some of them full of shells. At Whitecliff Bay we have deposits of about the same age, in which fossil mol- lusca are abundant. The large and beautiful bivalve Fig. 262. Cardita imbricata (Eocene). Cardita planicosta gives its name to the stratum where it swarms, in company with the univalve Turitella imbricataria. The Barton Clay is a higher deposit than the last mentioned, and it is perhaps the most renowned hunting-ground of the entire Eocene formation. It takes its name from Barton, on the Hampshire coast, and there, and also at Hordwell, the geologist will find FOSSIL MOLLUSC A. an abundance of the most beautifully preserved fossils among which, perhaps, the choicest are Valuta lucatrix, Typhis ptmgens, Rostellaria rimosa, Crassatella, and other genera which remind him of tropical seas. Fig. ^. Turritella. Yarmouth, in the Isle of Wight, is a good place to put up at for a few days in order to work the Upper 2 7 6 OUR COMMON BRITISH FOSSILS. Eocene beds of the district. The Hempstead Beds (sometimes regarded as Lower Miocene) run along the coast, and are especially well developed at the locality whence they take their name. The sea-bed there (at low water) is seen to be formed of stiff bluish clay, intercalated in which are strata of harder masses, probably hardened by diffused iron and lime, and by others formed of nothing but shells. All the shells, bivalve and univalve, belong to fresh-water species, such as Paludina lenta (which occurs in enor- mous numbers in the harder interstratified masses), Melania, Melanopsis, Cyrena, Corbula, Cyclas, Unio, etc. On the coast side of Yarmouth, towards Alum Bay a distance thence to the latter place of about seven or eight miles the geologist finds plenty of work, quite sufficient climbing, and a delight- ful sea view. The fossils lie strewn about the talus of the cliffs in all direc- tions. They are so in- numerable that the col- atkltta (Eocene), lcCt r g ivGS U P a11 en ' deavour to identify them, and simply " boxes them." They have been washed out of the beds in which they were originally de- FOSSIL MOLLUSC A. 277 posited, and the wash of the rain-water has strewn them thus over almost the entire face of the cliff. What myriads of Cerithium, Rissoa, Hydrobia, Me- lania, etc. ! This lovely Isle of Wight is surely the " garden " of English geology ! Where else in Great Britain, within so short a space, can the young geological student see so much, collect so many objects, or be able to roam over such a variety of geological and geographical scenic features ? From the Wealden and Greensand to the great backbone of Chalk, which runs through the length of the little island, right up through all the most interesting deposits of Lower, Middle, and Upper Eocene here we have a perfect " thumb-nail " geological sketch. Some of the Upper Eocene beds are not found elsewhere in Great Britain, as the local names they bear testify. The Isle of Wight will long be " classic ground " to the geologist, not only for its variety of geological forma- tions and plethoric abundance of fossils, but also because of dear old Dr. Mantells' book upon it which, if any young and ardent student happens to read it, he will straightway go, on the first oppor- tunity, and verify what that "grand old man" had to tell them about ! Cowes is a good place (rather too good for a quiet and economic student) to put up at, if he wishes to work the " Fluvio-marine " series. Thence he will make his way to Osborne (which would be sacred 278 OUR COMMON BRITISH FOSSILS. ground to him apart from the fact that it is the Queen's home), and there he finds an abundance of fossil shells, and possibly some of the Chara fruits which Sir Charles Lyell made famous. Limnea longiscata, Paludina lenta (which continued to live right on to the time when the Norwich Crag was formed in the later Pliocene age), Melania excavata, Planorbis, etc. all are to be found at Osborne in profuse abundance. At Bembridge and Headon, in the marls and shell-limestones, we have more than enough of Melania tttrritissima, Cerilhium mutabile, Cyrena pulchra, Ostrea Vectensis ; land shells, such as Helix globosa, Bulimus ellipticus (actually forming a limestone by its remains), and fresh-water shells, such as Limnea and the beautiful Planorbis discus. With the exception of the Hempstead strata (Isle of Wight), we have only doubtful and scanty remnants of Miocene deposit in Great Britain, and these are hardly worth mentioning so far as fossil collecting is concerned. Perhaps the most interesting of them in this respect are found in Suffolk, especially in the neigh- bourhood of Felixstowe a pretty sea-side watering- place and that of Ipswich. This is a splendid county for Pliocene fossils, locally and indeed generally known as " crag." The cliffs at the former place are simply masses of shells, and in the district there are plenty of " coprolite pits " places where the small phosphatic nodules (formerly believed to FOSSIL MOLLUSC A. 279 be the fossil faeces of animals, whence their name) are worked. More than two million pounds' worth of these " coprolites " have been excavated and con- verted into artificial manures since the late Professor Henslow found out what they were, nearly forty years ago. The " coprolites " are richest at the base of the shell-crags, where they form part of a bed in which we get the remains of mastodon, tapir, hipparion, rhinoceros, deer, etc. ; also roundish and elongated Fig. 265. Emarginulai fissura : a, natural size ; b, magnified ; c, lower side (Crag and recent). masses of coffee-coloured sandstones, which the visitor will find lying in heaps near every coprolite pit. Very singular are these roundish masses of sand- stone, most of which are about the size of one's fist. From Foxhall, the bed containing them (which usually lies directly on the London clay) extends to Felixstowe, and heaps of them may be seen by the roadside, waiting to be broken up for road-mending. They are very curious, for they represent a lost geological formation, older than the Coralline Crag (for they are also found under the latter), which is probably of late Miocene age. The rounded speci- 280 OUR COMMON BRITISH FOSSILS. mens go by the name of " box-stones " a term which has been given to them by the quarrymen. You strike them with a sharp blow of the hammer, and about one in every ten or so will break in halves, revealing the cast of a fossil shell, etc., within. When neatly broken, they form very interesting geological specimens. Among the fossil shells thus found enclosed are Pectuncidus, Cardinm, Cassidaria, Isocar- dium, Buccinum, etc. These " box-stones " are the Fig. 266. Pecten -varius (Crag Fig. 267. Fissurella Gr&ca and recent). (Crag and recent). broken up and rolled remains of a bed of sandstone, which once covered part of Suffolk, and which still underlies Diest, Antwerp, Brussels, and other places in Belgium, on the other side the German Ocean. These "box-stones" were broken up and rounded before the Pliocene period began, as is indicated by the fact that they are often found coated on their upper surfaces with fossil Barnacles, which clustered and spread over their surfaces as they lay on the floor of the shallow Red Crag sea. At Trimley, FOSSIL MOLL USC A. 281 Nacton, Bucklesham, Foxhall, Waldringfield, and thereabouts, these stones are very abundant. In the Ipswich museum there may be seen an almost perfect fauna, recovered from this missing and fragmentary British Miocene deposit. The Pliocene beds in England lie almost entirely on the east coast A deposit of this period has lately been discovered in Cornwall, and there are also patches in Aberdeenshire ; but the shells are too meagre and fragmentary in these outlying localities to refer the fossil-collecting student to them, especially when he Fig. -2.bg. Trochus (Crag and Fig. z6%.Mactra. recent). has access to the wonderfully rich Pliocene formations of Norfolk, Suffolk, and Essex, where everybody knows them by the name of " crags." The crag beds are richest near the coast, as at Walton-on-the-Naze, Felixstowe, Orford, and Aldborough, although they extend inland, and " crag " pits are very common in the neighbourhood of Ipswich ; and about Norwich we have the "crag" (latest formed of the entire 282 OLR COMMON BRITISH FOSSILS. series) which takes the name of that ancient and picturesque city. The places where the crag-pits are usually richest in fossil shells are on the heaths and commons so numerous in Suffolk and elsewhere, for the crags produce what the farmers call very "hungry land," and such unprofitable areas have therefore remained longer in their wild state than would have been the case had the soil been fertile. Fig. ^Q.Purpura lapillus (Crag Fig. zji.Buccinum undulatum (Crag and recent). beds and recent). But these heaths are glorious places in the early summer-time, when the sky is full of lark music, and the gorse and broom bushes are ablaze with aromatic yellow blossom, and the delicate crosiers of the bracken fern are everywhere bursting from the ground. Then, again, I know of no formation which more impresses the young student with the full meaning and significance of fossils than the Crag. Here FOSSIL MOLL USC A. 283 they are in the profusest abundance young and old, large and small, millions upon millions on every hand! They can be taken out with the fingers no hammer- ing is required ; and if the collector has come pro- Fig. 272. Pileofsis ungarica. vided with a wire-gauzed tray to sift the finer material, he will get all the lovely little shells, and plenty of foramenifera, etc., as well. Thirty or forty species of fossils can be collected in a very short time. Fig. 273. 7V/# Tellina crassa, T. obliqua, Mytilus edulis, Pecten opercnlaris> Cyprina islandica, Lucina borealis, Cardita senilis, Purpura tetragona> P. lapillus, Tro- phon (or Fusus) antiquus, T. con- trarius, Nassa reticosa^ N.granulata, Astarte Omallii, Cyprcza Europ etc. In many places, as at Tatting- stone, Bentley (in the pits near the station), Foxhall, Bucklesham, and elsewhere, the strata teem with Pectunctulus, Trophon contrarius, tetra- Cardita senilis, Nassa, etc. gona (Crag beds). The number of S p ecies Q f f ossil mollusca belonging to the Red Crag is two hundred and thirty-four, of which two hundred and sixteen are still in existence. In addition to this number, we must include about forty extraneous species. About one hundred and fifty of the above species are still living in British seas, whilst of the remainder, thirty- two are southern forms, and twenty-three northern a total of nine more northern species than are found in the Coralline Crag, thus far indicating a refrigeration of the climate. FOSSIL MOLLUSC A. 291 In the base of the Red Crag, the large angular flint nodules are usually found thickly encrusted with barnacle shells. The septarian nodules are perforated with holes, bored by various boring mollusca, such as Pholas, Saxicava,) and we frequently find the fossil shells of these borers in the holes they excavated. It Fig. 286.Nucula Cobboldice (Red and Norwich Crags). Fig. 285. Valuta Lam5erfi (Coralline and Red Crags). Fig. -&T.Trophon Con- trarius (Red Crag). is in this part of the Red Crag that the phosphatic stones, or " coprolites," are usually found in greatest abundance. A large number of mollusca, which lived in the sea that covered East Suffolk during the Crag period, 292 OUR COMMON BRITISH FOSSILS. are now living further south, in the Atlantic or the Mediterranean, having been driven from these areas by the increasing cold, which here reached its maxi- mum during the Glacial epoch. The best places to obtain Red Crag fossils are pits at Wherstead, Tattingstone, Bentley, Foxhall, Boyton, places near Woodbridge, Bucklesham, Walton, the Felixstowe cliffs, Bawdsey, Chillesford, Sudbourne, Butley, Aldborough, etc. The Norwich Crag was formerly called the <( Mammaliferous crag." But it has been shown that the mammalian remains are older than the shells associated with them. In Suffolk this crag occurs at Thorpe, near Aldborough, at Bulcamp, and Chilles- ford. Sir Charles Lyell gave to it the name of " Fluvio-marine Crag," on account of the large per- centage of land, fresh- water, and brackish- water shells it contains. It is usually regarded as nearly syn- chronous with the Red Crag, and as a fluvio-marine extension of the latter. The shells of the Norwich Crag are remarkable for their littoral, or shallow water character. The most abundant fossils are Littorina littorea, Purpura lapillus, Cardium edule, Mytilus edulis, Cerithium tricinctum, Turritella communis, Natica monilifera, Tellina prcetenuis, T. obliqua, etc. At the base of the railway cutting, about a mile from Aldborough station, we have found undoubtedly Red Crag shells associated with others we regard as equally undoubted Norwich Crag forms, indicating that here FOSSIL MOLLUSC A. 293 may be the junction of the two formations. This stratum lies in a denuded hollow of the harder and more consolidated strata of the Coralline Crag. From Thorpe Common, near Aldborough, the true Norwich Crag extends to the city whence it derives its name. Its greatest thickness is about eight to ten feet. This crag is distinguished by its abundance of recent forms, and the general absence of southern types of shells, thus showing that the cold was increasing. The total number of species of mollusca catalogued from it is one hundred and forty, of which one hundred and twenty-three are still living ; seventeen are supposed to be extinct. Of the above number, one hundred and one species are still living in British seas, twelve are Arctic and North American, eight Mediterranean, and two 'species Asiatic, the latter being Corbicula fluminalis and Paludina unicolor. From the fact that twenty species of shells belonging to the Norwich Crag are not found either in the Red or Coralline Crags, Dr. Gwyn Jeffreys thinks that there is some difference in their geological age, the Norwich Crag being more recent than the Red Crag, and its shells of a more arctic character. In 1865, the bed which had previously gone by the name of the Norwich Crag was shown to be composed of two deposits, usually separated by ten or fifteen feet of sand, etc. The upper bed is distinguished by a general absence of shore shells, such as Littorina and Purpura, and by the presence of shells affecting 294 OUR COMMON BRITISH FOSSILS. deeper water, and also by the greater preponderance of arctic or northern forms. After the formation of the Norwich Crag, the depression continued so as to bring the sea over its site, and it was along its floor that this Upper Norwich Crag was deposited. Hence it obtains a more extensive geographical distribution than the lower, or true " Fluvio-marine " Crag. In Norfolk it extends to about eight miles beyond Norwich ; and in Suffolk it is so well displayed at Chillesford that it sometimes goes by the name of the Chillesford Crag. At Aldeby, near Beccles, this crag is exposed in some brick-pits, and such shells as Mya arenaria are found abundantly, with both valves attached, standing upright in the sands as when they were alive. At Chillesford, in the stackyard near Mr. Crisp's house, this crag is seen to its best advantage, full of shells, many of them of a northern type, such as Mya truncata, Cardium Greenlandicum, Astarte borealis, etc. There can be no doubt that much con- fusion still prevails in the catalogue of the Norwich Crag shells, owing to the manner in which both the upper and lower crags were formerly confounded. In the pits on Thorpe and Sizewell Commons, near Aldborough, the ordinary Norwich Crag fossils are abundant ; whilst the brick-pits at Aldeby yield most beautifully preserved Upper Norwich, or Chilles- ford Crag. The Norwich Crag is seen resting on the Chalk at Thorpe, near Norwich, where the shell bed is about FOSSIL MOLLUSC A. 295 four feet thick. The bank of fallen or accumulated sand and shells will give the geologist plenty of " boxing " to do, for the fossils are extremely abun- dant, although usually in a very fragile state. The Norwich Crag also crops up in the pretty river-side calling place, Postwick Grove ; and at Whitlingham, on the other side the river. Bramerton, however, has long been regarded as the best place to get fossils at. They are here in a remarkably good state of preserva- tion, and there will be no difficulty in getting a score or more species. The Crag lies on the top of the chalk, and if the geologist lays bare the latter, he will see it drilled again and again by boring mollusca, showing that it was once the bare bed of the sea. Beyond Norwich there are several good places where the later Pliocene shells may be collected, as at Wroxham, Belaugh, Coltishall, Horstead, etc., all in exceedingly picturesque districts, and not far from the now celebrated "broads." Beds of shells also occur on the Norfolk coast, between Cromer and Sherringham, and at Weybourn, Runton, and Trim- mingham. 296 OUR COMMON BRITISH FOSSILS. CHAPTER XIII. FOSSIL CEPHALOPODS. I DON'T know any British fossils more common than some of those which come in for treatment in the present chapter. In China a few (like Orthoceras and Ammonites) are used in medicine, for the simple reason that nobody there knows anything about their origin, and their mysterious abundance is taken as an indication of the generative powers of the earth ! Even in Britain they have gained a place in folk-lore, and some have been immortalized in poetry, like the "snake-stones" (Ammonites communis), in Scott's "Marmion." In the Eastern Counties, where they abound although the specimens found there do not rightly belong to the place, for they are " derivatives," torn out of their parent rocks and brought thither during the Glacial period by ice agency, and re- deposited in the boulder-clays they are known by the name of " thunder-bolts." Thunder was always more dreadful to uneducated people than lightning, and all over the world there FOSSIL CEPHALOPODS. 297 has been a great desire to find the source of that mystical power the " thunder-bolt." In Kent, Cambridgeshire, and elsewhere, the rounded masses of iron pyrites originally formed in Fig. 288. Behmniitf Fig. 289. Belemnites Puzoncuvus Fig. 290. Restoration hastata (Lias). (guard and part of phragmacone). of an ancient Belemnite. the chalk, and subsequently denuded out of it, are called by this name. When broken, such masses (about as big as one's fist, or less) have a radiated 2 9 8 OUR COMMON BRITISH FOSSILS. structure. I have had them brought to me even by skilful astronomers with F.R.A.S. behind their names, as "meteorites." Can we wonder, therefore if less educated people call them by their other name of " thunder-bolts " ? Of course, lightning sometimes kills one of a herd Fig. 292.--Phrag- macone, showing chambers. Fig. zgi.Belemnites abbreviates, showing phragmacone. Fig. 293. Belcmnites mucronata (chalk). of cattle. I have a vivid remembrance of a veterinary surgeon, of such eminence that I dared not con- tradict him then, who triumphantly brought a real " thunder-bolt." A cow had been killed by lightning, and this "thunder-bolt" was found just underneath her. Where were your " scientists " ? There was the dead cow ; here was the object known for centuries as FOSSIL CEPHALOPODS* 299 the " thunder-bolt " ! Could cause and effect be more closely associated ? I " shut up." What is the use of arguing with a man who has made his mind up that he is right and everybody else is wrong ? The fact is, as just stated, the boulder-clay forming the subsoil of the Eastern Counties abounds with Fig. 294. Orthoceras, showing body- chamber at . Fig. *()$. Orthoceras laterale. derivative Oolitic Belemnites. These may be picked up on the surface. The poor old cow happened to have one underneath her when she died (I have not the slightest doubt she had frequently laid down on them before), and in this way the "thunder-bolt" theory received extra support ! Popularly speaking, both Ammonites and Belem- 300 OUR COMMON BRITISH FOSSILS. nites should be regarded as belonging to that group of animals which, rightly or wrongly, has for years occupied the leading position of the Invertebrates. Nautiluses and "cuttle-fishes" still figure at the top Fig. 297. Lituites articulatus. Fig. z<)6.Orthoceras, upper part shows chamber perfor- rJg. =98. Cyrtoceras Murchisoni ated by siphuncle. (Silurian). of this division, and many students accept that posi- tion as indicating their higher zoological rank. Many philosophical naturalists doubt this, but meantime we must accept it, for classification purposes at least. FOSSIL CEPHALOPODS. 3 01 My readers are fully aware that those parts most precious to the geologist viz. those which resisted decay because of their hardness and earthy composi- tion, such as shells, corals, spines, tests, etc. do not Fig. 299. The Pearly Nautilus, with animal in last chamber ; (recent, chambers in section to show structure). i, siphuncle ; x y, chambers ; z, body-chamber. necessarily represent the most important parts of the animal economy. The geologist has still to be thank- ful for those shreds of evidence which not long since were regarded by conchologists and others as the sole 302 OUR COMMON 1 BRITISH FOSSILS. ends of knowledge. Not much more than a quarter of a century ago, conchologists were careful only to collect shells ; they hardly cared for the creatures to whom those shells originally belonged, and many knew very little of their life-histories, now the most valuable part of them. Whatever may be the actual zoological position of the Cephalopoda (to which these Orthoceratites, Ammo- Fig. 300. Exterior of Shell of Pearly Nautilus (recent). nites, Belemnites, etc., belong), there is no question that they stand at the head of the Mollusca. This is evident from their high organization, their well- developed eyes, nervous and muscular systems, hydro- static apparatus, etc. Thanks to our public aquaria, most people are acquainted with the appearance of FOSSIL CEPHALOPODS. 303 such representatives of the order as the cuttle-fish or octopus, and can readily understand why the order is named Cephalopoda, because of the arrangement of the arms or feet, or whatever we like to call them, around the head. A few members of the order have their hard structures or shells outside their bodies as the Nautilus, for instance ; but the majority of them have the solid parts inside, which are called "cuttle- bones," "pens," etc. In the modern seas the shelled Cephalopoda (such as the Nautilus) are exceedingly rare, and the cuttle-fishes both abundant and widely dispersed. In the seas of the Palaeozoic epoch the reverse of this was the case the Nautilus family abounded ; the cuttle- fishes had not come into Fig " s<-- portion of Turriut*. existence. All the Cephalopoda are carnivorous in their habits now, and there is every reason to believe they were always so. We may practically divide the Cephalopoda into two divisions, for the benefit of the geological student anxious to be acquainted with the fossil remains of each group. First, there are those possessed of shells, such as the Nautilus and Ammonite family; and 304 OUR COMMON BRITISH FOSSILS. second, those which had hard internal structures, like those represented in the Secondary rocks by the numerous Belemnites, and in modern seas by the " cuttle-bones." The lovely shell of the modern striped Nautilus pompilius is well known, and may be seen in any Fig. 302. Internal shells of recent Cuttle-fish. museum. Its architectural and mechanical structure appears to be the same nowadays as it was in the early Palaeozoic ages of the globe. There is a series of chambers united by a tube called the siphuncle running through the centre of them. The last chamber is the largest, and is called the body-chamber, because it was last occupied by the body of the FOSSIL CEPHALOPODS. 305 creature. Each chamber was formerly filled by the animal, which retired from it as it grew larger, and formed another with more room ; but it maintained its organic connection with all of these deserted chambers by means of the siphuncle. These shelled Cepha- lapods ( Tetr -abranchiate or " four-gilled ") are sepa- rated in the Nautilus and Ammonite families. In the former, the divisions (septa) of the chambers are simple and curved, and the edges (sutures) plain, whilst the siphuncle usu- ally runs through the middle (central), as above Fig " described. In a few instances, however, the siphuncle is ventral, or at the base of the chambers. In the Ammonites, on the contrary, the septa are folded and very complex, and the sutures are zig- zagged, foliated, or irregularly lobed ; the siphuncle or air-tube is on the outside of the chamber (dorsal). These are very well-marked and easily recognized points of difference. It is as well to remember them, for, as far as external appearance goes, it is singular (as Dr. Nicholson has shown) how one group mimics the other, the real fact being that they were built up on the same external architectural lines. Thus, in the X 306 OUR COMMON BRITISH FOSSILS. Nautilus family we have (i) the straight-shelled group called, on this account, Orthoceras ; (2) another with the shell bent on itself, as Ascoceras ; (3) a curved shell, Cyrtoceras ; (4) a spiral form, Trochoceras ; (5) a discoidal kind, Gyroceras ; (6) discoidal and pro- duced, Lituites ; (7) and the involute, as represented by the Nautilus itself. In the Ammonite family all of these external shapes are repeated. Thus the straight ammonital form Fig. 304. Ceratites nodosus, is represented by (i) Baculites ; (2) Ptychoceras ; (3) Taxoceras ; (4) Turrilites ; (5) Crioceras ; (6) Ancylo- ceras ; and (7) the ordinary Ammonites. The Nautilus family, however, was by far the earliest to appear in the seas of the globe, and many of its genera had died out before the true Ammo- nites appeared, although the Goniatites are found in Silurian rocks. FOSSIL CEPHALOPODS. 307 Practically, therefore, we may regard the Nautilus family as being essentially Palaeozoic, and the Ammo- nites as characteristic of the Secondary period. The Nautilida include the following well-known genera of fossils, Lituites, Trochoceras, Gomphoceras, Orthoceras, Trochoceras, Phragmoceras> Cyrtoceras, Clymenia, etc. Fig- 35- Section of Shell of Ammonite, showing the large body- whorl or last chamber. In the Ammonitida we have the well-known Goniatites, Ceratites, Turrilites, Baculites, Hamites, Scaphites, Ptychoceras, Ancyloceras^ etc. We find these beautiful fossils of all sizes (although some so-called species are doubtless the young stages in the development of the larger kinds), as well as possessing wonderfully numerous kinds of external 3 o8 OUR COMMON BRITISH FOSSILS. ornamentation. Ammonites range in size from the lovely A mmonites lautus of the Gault, not bigger than a threepenny-bit, to the A. giganteus of the Upper Oolite, as large as a cart-wheel. The Cephalopoda first make their appearance in the Lower Tremadoc rocks. One form, Cyrtoceras precox, found at Llanerch, west of Tremadoc, is the oldest known. Orthoceras sericeum appears in the Upper Tremadoc strata at St. David's, Llanwern, and elsewhere. The Orthocemtites (as this genus is usually Fig. 306. Plan of foliation of edges of chamber of Ammonite. called when we speak of it in the plural) are most numerous in the Upper Silurian beds, as at Woolhope, Wenlock, and Ludlow. At the latter locality they are very numerous, and some species attain a large size. About thirty species of Orthoceras and Nautilus are known from the Wenlock formation alone ; twenty-four species of Orthoceras occur in the higher Ludlow series. The Aymestry limestone is singularly rich in places, in various kinds of Nautilidcz. Indeed, whenever the Upper Silurian strata are fossiliferous, FOSSIL CEPHALOPODS. 309 the geologist is sure to find numbers of this group present. The Devonian limestones cropping up in the neighbourhood of Torquay and Newton Abbot, and also the Upper Devonian rocks at Petherwin, in Cornwall, have yielded about sixty species of fossil Cephalopoda. At Petherwin the chief kind is the Fig. 307. Section of Liassic Ammonite, showing chambers filled with spar. beautiful Clymenia, of which eleven species are there met with. Goniatites is another genus not uncommon at Petherwin, although not so numerously represented, as far as species go, as Torquay. The richly coloured red and yellow limestones at the latter place are cut and polished, and then present a very lovely appear- 3 io OUR COMMON BRITISH FOSSILS. ance, being crowded with fossil, corals, shells, etc. ; and not unfrequently we see a white, vertebrate- looking organism cut through this will doubtless be an Orthoceras. In the Carboniferous limestone this family attains its maximum development, for no fewer than one hundred and sixty-nine species have been described from this and associated de- posits, up to and including the Millstone Grit. In this list we find fifty-nine species of Goniatites, forty-eight of Orthoceras, thirty-six of Nautilus, and seventeen of Discites (which is usually re- garded as a sub-genus of Nautilus). Some of the in- dividuals attain a gigantic Fig. 308. Beaked Ammonite. size. I have found fossil Nautili in Derbyshire and the Isle of Man which required a strong man easily to lift them. And, especially in the Irish Carboniferous limestone, speci- mens of Orthoceras are met with as thick as a man's thigh. Perhaps the commonest of the Carboniferous limestone Goniatites is G. sphcericus. It abounds at Castleton, in the Peak of Derbyshire at places in swarms. Higher up the series, in the Yoredale shales at Todmorden and Hebden Bridge, there are thin FOSSIL CEPHALOPODS. bands of black limestone completely made up of small Goniatites. In the shales which overlie the Fig. 309. Ammonites bifrons. Fig. 310. Side view of ditto impure coal-seams in the Millstone Grit of Yorkshire (es commums. Fig. 312. Side view of ditto. and Lancashire best seen, perhaps, in the neighbour- hood of Halifax and Oldham, we have a splendid 312 OUR COMMON BRITISH FOSSILS. fossil, Goniatites Listeri, as large as the palm of one's hand, and frequently converted into iron pyrites. The Ceratites of the Muschelkalk (Trias) of Germany is nearly allied to the Ammonites, and is a member of the latter family. The edges of the chamber-divisions in Ceratites are not so intricately folded as in the Ammonites proper, and, singularly enough, many of the young in some species of Fig. 313. Ammonites obtusns. Fig. 314. Side view of ditto. Ammonites pass through a Ceratite stage, in that their sutures are less complex then than during their adult life. About five hundred species of Ammonites have been already figured and described, as occurring in the formations from the Lias up to and including the Chalk. Palaeontologists have roughly separated them into six great groups as follows : (i) Those where FOSSIL CEPHALOPODS. 313 the external or dorsal edges of the shell are marked by an entire ridge or keel; (2) those in which the back is crenated ; (3) those having the back sharp ; (4) those with the back channelled ; (5) those with the back squared ; and (6) those with the back round or convex. The Lias and Oolite abound in Ammonites. Fig- 315- Ammonites amaltheus^ with a plan of foliation of chambers, and section of back of shell. About two hundred species have been found in the Lias strata alone, and they are so persistent that thirteen zones are distinguished by the presence of certain species of them, which have a limited range. The name of " snakestone " is given to them at Whitby, where Ammonites of many kinds abound. They are found in blue nodules, which, when broken OUR COMMON BRITISH FOSSILS. open, reveal the coiled-up ringed shell, wonderfully resembling a snake in such species as Ammonites communis, and still more wonderfully resembling one when they put a " head " on, with eyes in as they sometimes do. Zones of Ammonites also occur in the Oolitic rocks, both of Eng- land and Scotland, as those of A. Calloviensis, etc. In Scotland there is an extensive outlying series of Liassic and Oolitic beds, as in Skye, and other islands, and in Sutherlandshire remnants of a vast sheet of Secondary strata which probably once completely covered the Western High- Fig. 316. Ammonites varicosiis. Fig. 317. Ammonites Cooperi. lands, where they have long been removed by de- nudations. In the Oolitic strata of Sutherland an impure coal is worked, as at Brora, and there the FOSSIL CEPHALOPODS. 315 roof over the coal is literally crowded with the elegant Ammonites Jason. Mr. W. Hudleston, F.R.S., has remarked on the suddenness with which about forty species of Ammo- nites make their appearance in the Kelloways rock of Yorkshire. He thinks it due to a "regular inva- sion." Fossil Nautili are not unfrequent, both in Lias and Oolite ; and some very pretty ones, cut and uncut, are offered for sale at Whitby, Scarborough, Lyme Fig. 318. Ammonites Maniellii. Regis, Weymouth, and other seaside places .where fossiliferous strata occur, and where people come with a little scientific taste, more leisure, and most money. The group of Ammonites technically known as Ornati occur plentifully near Scarborough. At Cayton Bay, Filey, and Pickering, in Yorkshire, we have well- known localities for very large Ammonites, such as the easily recognized Ammonites excavatus, A. verte- bralis, A. perarmatus, A. plica tilis, etc. 316 OUR COMMON BRITISH FOSSILS. The Cotteswold district is a capital one for "snake-stone" hunting. There we find beds full of Ammonites Parkinsoni and A. Humphresianus. In the neighbourhood of Kimmeridge Bay where lie the strata forming that division of the Oolite which takes its name from the locality there are numerous fossil Ammonites, all flattened, and usually of a creamy-white colour. We often get fragments both of the Kimmeridge and Oxford Clays in the Boulder Clays of the Eastern Counties (where they have been Fig. 319. Ammonites falcatus. Fig. 320. Ammonites lautus. brought by ice-action), and they are sometimes so full of these and other Secondary fossils that the student may study the Dorsetshire, Oxfordshire, and Lincolnshire Oolites (or their representatives) without leaving his own parish. Of course, in the neighbourhood of Portland we may see any number of huge, bulky Ammonites in the rockeries of gardens. These large types are found plentifully in the Portland stone, although only as natural casts. FOSSIL CEPHALOPODS. 317 Mr. Robert Etheridge, F.R.S., in his presidential address to the Geographical Society of London, stated that "the whole of the Secondary rocks, from the base of the Lias to the highest Chalk, have been subdivided and specialized by the Ammonitidce a classification holding good for Europe, India, and America, many species being the same both in the eastern and western hemispheres." Perhaps the commonest species of Nautilus in the Inferior Oolite is the elegantly shaped Nautilus hexa- Fig. 321. Crioceras. gonus. It is found in the " Cornbrash " of Northamp- tonshire, Kellaways rock, and other subformations. I ought to mention that certain fossils called Trigonellites are found in the Secondary strata, and that they have always been regarded as the "oper- cula," or " doors " of Ammonites. The late Charles Moore, F.G.S., of Bath, was strongly against this 1 notion. In those subdivisions of the Oolite which are of 3i 8 OUR COMMON BRITISH FOSSILS. purely argillaceous or clayey origin, the fossil Ammo- nites still retain their pearly, iridescent nacre, or "mother-of-pearl" coating. This is the case with them in the Oxford Clay, and also in the Gault a subdivision of the Cretaceous or Chalk formation. Indeed, in the latter the fossils are perhaps more Fig. 323. Fragment of T. t^lbercnlatus. Fig. 324. Hamites attenuates. beautifully preserved in this respect than in any other formation, although I have laid open Strophomena and other fossil Brachiopods in the Wenlock Shales (another clayey deposit), which showed distinct nacreous lustre at first, but immediately vanished on exposure to the air. FOSSIL CEPHALOPODS. 319 The Gault near Folkestone is a magnificent store- house of fossil Cephalopoda. Both on the beach and in the brick pits on the common any quantity of fossils can be obtained. The Ammonite family seems Fig. 325. Fragments of Hamites attenuatus. to run into strange and fantastic external forms in the Cretaceous strata, commencing with the Lower Greensand, and passing upwards through the Gault, Fig. 326. Tutrilites Bergerii. Fig. 327. Turrilites iindulatus. Upper Greensand, and Lower Chalk. The regularly coiled Ammonites now become irregular. Sometimes they are only partly coiled, as in Crioceras ; at others hooked at one end, as in Hamites, or coiled up at 320 OUR COMMON BRITISH FOSSILS. both ends, as in Scaphites, or they may be quite straight, as in Baculites. The Gault is remarkable Fig. 528.- Turrilites costatus. for its abundance of these types. In the Lower Chalk they are represented chiefly by the spiral form Fig. 329. Turrilites tuberculatus. Turrilites. At Atherton, in the Isle of Wight, these fossils occur in abundance. In the South of England FOSSIL CEPHALOPODS. 321 generally, wherever the chalk marl is worked, many of these forms of Ammonitidce will be found. A good many true Ammonites range to the very highest part of the Norfolk Chalk, which is, perhaps, the highest horizon in England such as Ammonites Rho- tomagensis, etc. Fig. 330. Phragmoceras ventricost. The Belemnites belong to the Dibranchiate (or two- gilled) division of Cephalopoda. The fossils known by this name are the hard internal parts or " guards " of an extinct family of cuttle-fishes. It will be seen, in a perfect Belemnite, that the upper and thicker Y 322 OUR COMMON BRITISH FOSSILS. part is usually hollow ; sometimes, however, it is occupied by an inverted conical object, divided into nearly horizontal chambers. The latter is called the phragmacone. Its chambers are usually traversed by a tube or siphuncle, as in those of the Nautilus, and the internal parts of the extinct animals which formed the Belemnites were chiefly contained within the last-formed chamber, as the body of the whole animal is in the Nautilus. The true Belemnites only occur in Secondary rocks of this country. In the Chalk we have a sub-genus termed Belemnitella, which may be distinguished from the former by the slit in the upper part of the guard. It is clearly seen in that most abundant and widely distributed Chalk species Belemnitella mucronata. In the Lias and Oolite, Belemnites are marvel- lously abundant. Near Whitby the limestone fre- quently appears as if wholly composed of them. Scores are often seen on the surface of a single slab. No fewer than one hundred and fifteen species have been described from the Oolitic rocks of Great Britain alone. There is as great variety in their sizes as in the other families of Cephalopods. For instance, we have some species in the Lias whose " guards " are a foot and a half long ; and others, like Belemnites minima, found plentifully in the Lower Cretaceous strata and particularly in the Gault only about an inch long. Genuine cuttle-fishes, allied to existing genera, FOSSIL CEPHALOPODS. 323 are also met with, chiefly in the Oxford and Kim- meridge Clays, where they have been so well preserved that even their " ink-bags " are fossilized clays being always the best preserving grounds for fossils. After the long periods of time which have elapsed since the ancient creatures secreted the pigment, it is still avail- Fig- 33 1- Baculites vertebralis : c, cast of detached chamber. able, and I have seen sketches in sepia made en- tirely from the fossil ink of extinct cuttle-fishes ! The limits of space prevent me doing more than merely sketching the outlines of the history and affinities of our most interesting and common fossils. The student who collects will soon learn more about them ; particularly in the magnificent volumes pub- 324 OUR COMMON BRITISH FOSSILS. lishcd by the Palaeontographical Society of Great Britain, which form one of those unconscious monu- ments of English voluntary science, the rest of the world can only wonder at. One common lesson is written upon the rocks of all geological ages by these palaeontological characters that in the midst of life we are literally in death ! That the platforms, on which the vitality of animals was temporarily exercised during one period, had their foundations laid down, and were built up, by the death and extinction of the species of a preceding period ! " Upwards and onwards " has been the motto of the Organic Life of the globe, in spite of those " fallings, off, vanishings," of which Retrogradation takes par- ticular note. One cannot reverently study these incomings and outgoings of the life-forms of succeed- ing epochs without feeling that " one Divine Purpose runs " throughout the ages, connecting and uniting them into a single great Life-scheme, of which we as yet see only the tangled and disjoined portions ! INDEX. A Abundance of fossils. 3 Acorn-shells, 202 ; larval changes of, 203 Actinocrimis, 117, 127 Agelacrinus, 131 Allman on graptolites, 40, 44, 45 Ammonites, 300, 305 ; number of species, 312 ; zones of, 314 Ammonitidcz, 307 ; in Kelloways rock, 315 ; localities for, 315, 316 ; at Portland, 316 ; variation in, 319; in Chalk, 321 Ananchytes, 151 Anodonta Jukesii, 239 Anthracene^ 251 ; in ironstone, 251 Apiocrinites, 128, 129 Aporose corals, 63, 64, 67 Arenicolites, 164 Astidia and sea-mats, 212 ; larva of, 213; relation to brachiopoda, 214 Aspidophylhun, 87 Astr&a, 69, 79 Australian Brachiopoda^ 231, 232, 234 Aymestry limestone corals, 77 B Barnacles in Silurian, Rhretic, Oolite, and Chalk strata, 203 ; in Coralline and Red Crag, 204 Barton Clay, fossils of, 274 Beith, corals at, 87 Belemnites, 321 ; structure of, 322 ; in Lias and Oolite, 322 ; their relation to cuttle- fishes, 323 Benthall Edge, corals at, 76 Black Head, Carboniferous lime- stone at, 1 7 Blastoidia, position of, 112 Boring sponges, 13 Box-stones, 279 ; fossils in, 280 ; localities for rinding, 281 Brachiopoda, 222 ; life-histories of, 223 ; geological antiquity of, 223 ; erroneous notions concerning, 224 ; larval stages of, 224 Bracklesham, Tertiary fossils of, 274 Bradford (Wilts), encrinites in clay, 117, 128 Bray Head, Old/iamia at, 37, 38 Brittle-stars, 132; structure of, 134 Cambrian fossil worm-tracks, etc., 163 mollusca, 245 rocks, Lower, sponges in, 1 1 rocks, Oldhamia at, 37 star- fishes, 131 trilobites, 189, 192 Cambridgeshire coprolites, 208 Carboniferous corals, 65, 69, 82, 87, 88, 89 ; of Scotland, 85 crinoids, 126 Y 3 INDEX. Carboniferous encrinites, 115, 122 limestones, 29 ; foraminifera in, 30, 31 mollusca, 248 ; localities for finding, 248, 249, 250, 251 polyzoa, 217 trilobites, 191, 198, 199 worm-tracks, 166 Carpenter, encrinites dredged by, 104, 122 Carpenter, Dr. , on shells of brachio- pods, 226 Carrick mountain, Oldhamia at, 37 Carruthers on graptolites, 44, 47 Cephalopoda, zoological position of, 302 ; division of, 303 ; shelled, 305 ; first appearance of, 308 ; Carboniferous, 310 ; localities for, 3io,3" Gault, 319, 320 Ceratites, 312 Chain-coral, 74, 79 Chalk fossils, character of, 265, 266 ; Lower, 266 Chalk, white corals of, 95 ; sponges in, 16 ; foraminifera, 30 ; en- crinites, 123, 129 Chert, 21 Choanites, 25 Cladograptus, 47 Cladophora, 46 Cliffs of Mohr, ^orm-track in flags of, 1 66, 167 Climacograptus, 48, $o Clitheroe, encrinile heads in seams, 127 Ccenenchyma, 68 Comafu/a, 108 Coniston limestone corals, 81 Corals, ancient, genera of one species, 82 recent and fossil, 55 ; classi- fication of, 58 ; abundant, 73, 74, 75, 76, 78, 79, 80, 81, 83, 84, 85, 87, 88, 89 ; in flints, 95 Coral-reefs, 69, 70, 77, 83, 90, 94 Coralline Crag, 284, 285, 286; northern shells in, 286 ; Dr. Woodward on shells of, 287 Corallines, 35 Corinth' fes, 170 Cowes, fluvio marine fossils at, 271 Crag beds, 281 ; abundance of fossils in, 283 ; division of, 283 corals in, 97 fossils, localities for, 289, 290, 292 polyzoa, 219 ; localities for, 219 Cretaceous corals, 90 echinoderms, 152, 153, 156, 157 foraminifera, 30 mollusca, 262 ; localities for finding, 262, 263, 270 polyzoa, 217, 218, 221 sponges, 16, 18, 25 strata, single-corals character- istic, 94 star-fishes, 137 Crinoid, recent, 104 ; Palaeozoic described, 113 Crotalocrinns described, 125 Crustacea, classification of, 205 ; larval changes of, 205 ; geological appearance of, 205 ; localities for finding fossil, 206, 207 ; cretaceous, 206 Cruziana, what it is, 159 Crytograptus, 47 Cyathaxinia, 88 Cyathocrinus, 127 Cyathophyllum, 78, 79, 82 Cyprides in coal measures, 202 Cystidea, position of, 1 12, 130, 131 D Doidrograptus, 47 Devonian brachiopoda, 237 cephalopoda, 309 ; localities for, 309 corals, 82, 83, 84, 85 encrinites, 115 ; comparatively rare, 126 mollusca, 246, 247 ; loca]:Hes of finding, 247 trilobites, 198 Dichograptus, 47 INDEX. 327 Diercwograptiis, 48 Didymograptus, 47 Diplograptus, 47, 50 Dissolution of spicules, II Ditrttpa, 173 Dudley limestone corals, 73 Dumfriesshire, graptolites of, 49 E Earliest trilobites eyeless, 184 Echinodermata, inter-relations of different forms, 107 ; their young condition, 1 10 ; structure of, 144, 146 ; of fossil, 147, 149 Echinozoa, 105 Echinus, 109 Eglwyseg corals, 87 Eifel Mountains, crinoids in, 126 " Encrinital limestone," 118 marble, 120 Encrinite, description of an, 112 Encrinites, 98 ; zoological position of, 99 ; living, 107 ; abundant, 115, Il8, 120, 121, 122, 124, 127, 128 effects of muddy water on, 1 1 5 Primary, 115 Secondary, 128 Encrinus moniliformis, 128 Eozoon Canadense, 28 Estheria> 202 Etheridge, Mr., on sponges, 19 ; on Productus, 233 ; 3*7 E^^plectella aspergilhim, 1 1 Eurypterida, 201 Fasciailaria aurantiutn, 221 Favosites, 79, 82, 84 Eeather-star, 107 Felixstowe, fossil lobsters at, 207 ; fossil shells at, 278 " Fire-stone," 25 " Five-fingers " star-fish, 132 " Flint-meal," 20, 23 Flint nodules, formation of, 34 Flints, sponges in, 20, 23 ; encri- nites on, 123 Fossil cephalopods, 296 ; folk-lore of, 296 worms, 158 Fossils, abundance of, 3 ; doubtful classification, 14 ; popular names, 26 Foraminifera, 28, 29 ; in carboni- ferous limestone, 30 ; in white chalk, 30 ; to prepare, 50 Fusulina limestone, 29 Fusus contrarius, 289 Gault echinoderms, 153 fossils of, 263 Gasteropoda, differentiation of, 242 Girvan, corals at, 82 " Glass-rope" sponge, 18 Glyptocrinus, 124 Goniaster, 132 Goniatitts, in Yoredale shales, 1 1 6, Gonotheca, 41, 42, 44 Graptolites, 38 ; zoological position of, 40 ; structure of, 42 ; abun- dant at, 50, 51, 52, 53 ; in shales, 54 Graptolithus, 47 Gravel flints, sponges in, 27 Greensand echini, 153 fossil mollusca of, 263 ; lo- calities for, 264, 265 sponges in, 19, 25, 26 H Hafod, corals at, 88, 89 Halysites, 78, 79, 84 Hampstead beds, fossils of, 276 Heliolites, 62, 78, 81, 82, 83 Hexactinellida, n, 12, 23, 24, 25 Hinde on sponge spicules, 19 Hopkinson on graptolites, 40, 41, 46 Hunstanton, corals at, 94 328 INDEX. Hunting-grounds for Silurian star- fish, 138, 139; for Rhsetic star- fish, 140; for Lias star-fish, 141 ; for Oolitic star-fish, 141 ; for Chalk star-fish, 142 Hyalonema, 18 ffymenocaris, 201, 204 Ipswich, crag corals near, 97 ; fos- sil lobsters at, 207 ; coprolite pits at, 207 Ireland, corals in, 87 Jaws of modern worms, 162 ; of fossil, 162 Kentish rag, sponges in, 19 Kirkby - Lonsdale, worm - tracked flags of 161, 167 Lamp-shells, 222 ; origin of name, 225 ; description of valves of, 225 ; structure of shells of, 226 ; internal structure of, 227 ; loops and spirals in, 228 Lapworth on graptolites, 40 Lessons taught by fossils, 324 Lias corals, 90 encrinites, 128 mollusca of, 254; in Scot- land, 256 star-fishes, 137 Liassic ammonites, 313 - rocks, eozoon in, 28 ; fora- minifera in, 29 " Lily Encrinite," 128 Limestone, foraminifera in, 28 Lincolnshire, Oolite strata of, 257 ; quarries in, 258 Lithistida, 11, 12, 19, 23, 25, 26 Lithostrotion^ 88 Llangollen corals, 87 Locomotive organs of star-fish, 123 Longmynd rocks,. worm tracks in, 166 London Clay, encrinites, 129 fossils of, 272 ; localities for, 273 ; fossil wood in, 273 Lonsdalia, 87, 88 Ludlow rocks, sponges in, 10 M Madrepores, 67 Malvern Hills, corals in, 78 Manon, 26 Marble, encrinite, 1 20 Marsupites of Chalk, 112, 129, 131 Microscope, use in geology, 27 Micro zoa, 18 " Millepore-bed," 91 Moffat, graptolites at, 49, 50 Mold, Lonsdalia at, 87 Monactinellidce., n Montilivaltia, 91 Moseley, Professor, on corals, 6c Mollusca, antiquity of, 239 ; com- position of shells of, 240 ; calcitic and arragonitic structures in shells of, 241 ; geological value of, 241 ; structure of shells of, 243 ; in- terior scars and markings in, 243 ; siphonate and asiphonate kinds of, 244 ; first appearance of, in time, 244 ; geological localities for first species of, 244 fossil (Palaeozoic), 239; Second- ary, 253 ; Tertiary, 271 Mullock Hill, corals at, 84 N Nautili in Yoredale shales, 116 Nautilus family, division of, 306, 307 fossil, in Oolite, 317 potnpi Hits, 394 Nicholson on graptolites, 44, 46 INDEX. 329 Northamptonshire, fossil mollusca of, 257 Norwich, corals near, 96 Crag, 292 ; fossils of, 292, 293 ; division of, 293 ; localities for fossils in, 294, 295 Nummulite limestone, 29 O Oldkamia, 35 Oniphyma, 78, 79 Oolite, Great, sponges in, 19 fresh-water beds of, 251 ; fossils in, 261 mollusca of, 255 ; localities for, 258, 259, 260 Yorkshire, fossils of, 257 Oolitic corals, 91 Crustacea, 206 echinoderms, 154; localities for, 154-6 encrinites, 117, 128 polyzoa, 217 Old Red Sandstone lakes, the, 240 Ossicles of encrinites, 114 Orlhoceratites, in Yoredale shales, 116 Ostrea vesdcularis, 268, 269, 270 Palaechinus, structure of, 153 Palaeontographical Society, 324 Paludina, Wealden, 239 Paramoudra, 26 Peak district, encrinites in, 118 " Pear encrinite," 128 Pentacrinus, 113, 128 Pentamerus Knightii, 78, 235 Pentremites, 130, 132 Perforata, 66 " Periwinkle Rocks," 38 Permian mollusca, 251 ; localities for, 252 Phillipsastraa, 89 Phosphorite, 208 Phosphate, sponges converted into, 26 Pliocene fossils, 278 Planorbis, Eocene, 240 Platycrinus, 127 PleurograptuS) 48 Polyzoa, appearance of living, 21 1 ; their relation to Brachiopoda, 214; localities for fossil kinds, 215-217; in Coralline Crags, 284 Portland stone sponges, 19 Poteriocrinus, 122, 127 Prestwich on the Crags, 285 Productida, 232 Productus giganteus, 232 Llangolliensis, 232 Pyritized encrinites, 128 Purbeck limestone sponges, 16 Radiata, 104 Radiolarians, 18, 32 Ramsey Island, graptolites in, 48, 53 Rastrites, 43, 47 Reef-building corals, 69 " Rose encrinite," 125 Rhabdophora, 40, 46 Rhsetic mollusca, 253 ; localities for, 253, 254 Rhodocrinus, 125, 127 Rhynchonellidte, 229 Rhynchonella socialis, 232 Wilsonii, 232 Rugosa> 62, 64 Saccosoma, 129; of Oolite, 112 Salenia, 152 Scarborough, corals near, 91 " Screwstones," 119 Sea mats, 209 ; structure of, 2IO ; distribution of fossil, 2 1 1 Secondary corals, 90 Serpula, 170; in Oolite, 172; in Chalk, 173 Sertularians, modern, structure of, 41 Silurian cephalopoda^ 308 330 INDEX. Silurian corals, 70, 83 encrinites, 115, 117, 124, 125 foraminifera, 31 fossil mollusca, 245 ; altera- tions in appearance of, 245 ; im- pressions of, 245 ; localities for finding, 246 fossil worms, 168, 170, 171,172 graptolites, 38, 48, 49, 52 sponges, 13 star-fishes, 138 trilobites, 189, 192 Siphonia, 12, 25 Sorby, Dr., on corals, 64 Spiri/ercE) 228 Spirorbis, 169, 170 Spongites, 21, 22 Sponge-flesh (sarcode), 6, 8 Sponge gravels, 26 Sponges, boring, 13 calcareous, 10, 14, 16 Carboniferous, 17 chitinous, 10 compound animals, 7 Cretaceous, 16, 18, 25 Flint, 20 Great Oolite, 19 Greensand, 19, 25, 26 in Lower Cambrian rocks, 1 1 in Ludlow rocks, 10 Kentish Rag, 19 Portland stone, 19 Purbeck limestone, 16 recent, 13, 19 siliceous, 1 1 Silurian, 13, 17 spicules of, 9, 10, 18, 19 Star-fishes, 130 ; deep sea, 136 Starkie Gardner on modification of mollusca, 242 " St. Cuthbert's Beads," 128 Strophomena, 231 Stroud, corals near, 93 Swansea, zaphrentis at, 86 Tabulata, 58 Tcntaculites, 170 TerebratulidcZ) 228, 234 Terebratula hastafa, 234 grandis, 235 Tertiary corals, 96 Crustacea, 206 ; at Sheppey, 207 mollusca, 271 ; importance of, 271 ; in Thanet sands, 272 ; localities for, 272 Tetractinellidce, 1 1, 12 Thamnastraa, 91 Thecosmilia, 93 Thomson, James, discovery of sponge spicules, 18; on corals, 85 Sir Wy ville, encrinites d redged , 104, 122 Thunder-bolt, story of a, 298 Thunder-bolts, 296, 297 Tortoise-encrinites of Chalk, 1 12 Trilobites, 174; folk-lore of, 175; etymology of, 176 ; relations of, 176 ; metamorphoses of, 177 ; their relation to king-crabs, 178; resemblance of larva of king-crab to, 178 ; compound eyes of, 180, 185 ; sizes of, 181 ; Barrande on larval stages of, 183 ; Owen on sexes in, 184; Buckland on eyes of, 185 ; bottom feeders, 187 ; Salter on, 187 ; relations of species of to shrimp, parasite (Bopyrus), 188 ; moulting of, 189 ; relation to recent serolis, 192, 193 ; to recent opus, 193 ; localities for finding, 194, 199 ; classification of, 199, 200 TrigonellifeSy 317 Tubed worms, 162 U Upper Silurian Brachiopoda, 237 ; localities for, 236 Ventriculites, 12, 21, 24 "Venus' flower-basket," n, 12, 24 INDEX. 331 W Wales, North and South, graptolites in, 52, 53 North, corals, 80, 87 Wandering worms, 163 Water- vascular system of echinozoa, 107 Wealden, 261 ; fossil mollusca of, 262 Wenlock Edge coral-reef, 70, 77 corals abundant, 75, 82 Wight, Isle of, a good fossilizing place, 271 Windermere, graptolites at, 51 Wood, Mr., 127 Searles, on the Crags, 285 ; 286, 287, 288 WoodocrinuS) 127 Woolhope Valley corals, 78 Woolwich and Reading beds, fossils of, 272 Worm-tracks, modern, 159; fossil, 159 ; indicative of subsidence, 160; in millstone grit, 165 Worm-tubes, 164, 165 Wren's Nest, corals at, 71, 74 Yarmouth (Isle of Wight), a good locality, 275, 276 Yoredale beds, encrinites in, 116 Young, Mr. J., on microzoa, 18 Zaphrentis, 79, 85 THE END. 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