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Un dee symboles suivants apparattra sur le derniire imege de cheque microfflche, ssion ie cee: le symbols -^ signiffle "A 8UIVRE ", ie symbols V signiffle "FIN". Mapa, plates, charts, etc., may be filmed at diffferent reduction ratios. Thoae too large to be entirely Included In one expoaure are filmed beginning In the upper left hand corner, left to right and top to bottom, as many frames as required. The following diegrams iiluatrate the method: Les csrtes, planches, tableaux, etc., peuvent Atre ffllmto i dee teux de rAduction diffffArents. Lorsque le document est trop grend pour Atre reproduit en un seul clichA, II est ffilmA A partir de i'engle supArieur gauche, de geuche A droite. et de haut en bes. sn prenant le nombre d'imeges nAcessaire. Les diogremmes suivents lllustrent la mAthode. 1 2 3 1 2 3 4 6 6 ON TAB SILURIAN & DEVONIAN ROCKS OF NOVA SCOTIA. BY J. W. DAWSOK, LL.D., F.G.S. I [Oommunicated to the Natural History Society of Montreal.] In the poninsula of Nova Sootia, the formations older than the carboniferous system, which is there so largely developed, are ro> presented by disturbed and partially metamorphosed beds, occupy- ing a broad belt of country on the douth-oastern or Atlantic coast, and certain irregular hilly tracts in the interior. These beds were described by mo in a paper communicated to the Geo- logical Society of London in 1849, and subsequently in my "Acadian Geology;" in which work will bo found references to the labours of previous observers. These notices were confessedly very imperfect, owing to the difficulties of the formations them solves, the deficionoy or bad state of preservation of the fossils, and the absence of sufficient suites of those for comparison. With tho view of remedying these de^onoies, I have embraced such opportunities as have occurred to mo since tho publication of "Acadian Geology," to study those rocks in those parts of the country which appeared to promise tho most satisfactory roHults. My collections of fossils have also been increased by contributions received from Dr. Webster of Kentvillo, who has long dirceted his attention to tho Now Canaan and Nictaux districts, which I liavo had tho advantage of exploring under his guidance; from thollov. Si Silurian and Devonian Roch D. Honeyman,* who has carefully collected the fossils of the Ari saig section, and from Mr. C. F. Hart of Wolfville. Prof. Hall of Albany, has also kindly consented to apply his unrivalled knowledge of the palaeozoic fauna of America to the determi- nation of the fossils, and has enabled me to publish with this paper, his descriptions of the more important new species. With these aids, though aware that the complete sol aon of all the difl&culties of these deposits must await a systematic and detailed survey, I hope to fix with certainty the geological position of several important series of beds, and thus to afford Bome data for comparison with the formations of similar age in other countries. Fig. 1. — Explanation of the Map and Section, Secondary Trap. New Rod Siindstono (Permian or Trfasaic.) Carboniferous. (In eastern part of NoTa Scotia proper.) Devonian. Middle and Upper Silurian. Metamorphosed Lower Silurian, Granite. The numbers refer to the section and to the corresponding shades of the map. 0) (3) (3) (4) (6) 0) In my paper of 1840, 1 attempted to arrange the whole of thoso infra carboniferous rocks of Nova Scotia, in two great divisionB : (1.) The slate and quartzitc fornniiion of the Atlantic coast. (2.) The slaty, calcareous, and ferruginous formation of tho in- land hills. Tho second of thoHo groups will bo found in tho sequel to include beds ranging from tho Middio Silurian to tho lower Devonian. Tho first is certainly older, and probably of Lower Silurian ago. * See also a paper hy Mr. Houeyman, la tho Transaotioni of thu N. 8. Lit. & Sci. Society. • age, ha aon Of i 1 ' . oj Nova Scotia* 8^ I. — Lower Silurian. The Atlantic coast series, which I regard as probably of this age, has afforded little that is new since my former publication on the subject. It extends continously, with prevailing east and west strike and northerly dip, from Cape Canso to the middle of the peninsula at Halifax Harbour. Thence it continues with pre- vailing north-east and south-west strike to the western extremity of the province. Its most abundant rocks are coarse clay slate and quartzite in thick beds. In some districts the slates are re- presented by mica-schist and gneiss, and interrupted by consider- able masses and transverse bands of intrusive granite. It has afforded no fossils ; but it appears to be the continuation of the older slate series of Mr. Jukes* in Newfoundland, which has afforded trilobites of the genus Pamdoxides.-f These fossils would indicate a position in the lower part of the Lower Silurian series, possibly on the horizon of the Potsdam sandstone or Lingu- la Flags. If so, the Lower Silurian limestones are either absent or buried by the unconformable superposition of the next series, or of the carboniferous bods which in some places immediately adjoin these older rocks. It is however proper to state that on a comparison of these rocks with the series of altered deposits from Eastern Canada, collected by the Canadian Survey, and elaborately examined by Mr. Stcrry Hunt, they appear more nearly to resemble those of the Hudson River group than any other of the series. It seems also, that chiastolito and staurotido, which occur abundantly in ponic parts of the Nova Scotia coast series, as for example, at Cape Canscau and in Shclburne, are characteristic in Canada and Now England of altered Tipper Silurian and Devonian rocks. It is possible that this last fact may be accounted for by the local oc- curence of some beds newer than the others ; and the characters of the Silurian and Devonian scries, as scon elsewhere in Nova Scotia, seem at least to exclude the mass of these coast rocks from any formation newer than the Middle Silurian. II. — Middle and Upper Silurlin. The inland group of motamorphic rooks is more variable in its character, presenting many varieties of shales and slates some* •Survey of Newfoundland. t Salter, Procuodinga Geological Society of London, 18S0. 'I Silurian and Devonian Rocks times talcose and chloritic, often coarse and arenaceous, and asso- ciated with beds of sandstone and quartzite, and with calcareous layers. In some districts there are also extensive beds which have the appearance of interstratified igneous products both of uorn- blendic and felspathic composition. The associated igneous rocks are granite (which appears to be continuous with that of the coast series and intrusive), syenite, diorite, porphyry and compact fel- spars. The more highly altered portions are penetrated by num- erous veins of peroxide and carbonate of iron, with copper and iron pyrites. These beds, as well as the overlying Devonian series, have been thrown into folds, varying in direction from east and west to north-east and south-west, and have been at the same time much altered and disturbed by plutonic rocks. They afterwards suflFcred extensive denudation, forming both anticlinal and syn clinal valleys, in which were deposited beds of the carboniferous system, and of the New Red Sandstone of Nova Scotia, a deposit still of uncertain age.* This denudation lifis appar- ently been so complete as to remove from view nearly all the softer and least altered beds, the remains of which appear principally at the margins of the valleys now filled by the carboniferous series. Even in these exceptional spots they have in some instances been further obscured by trappcan eruptions of carboniferous or later date. The following are the principal localities in which I have been able to obtain determinable fossils. The geographical posi- tion of these points is noticed in the accompanying map. (Fig. 1, p. 132.) Aribaiq. Near this place, at the extreme northern limit of the Silurian system on the eastern coast of Nova Scotia, is one of the most in- structive sections of these rocks in the province. At the eastern end of the section, where they are unconformably overlaid by lower carboniferous conglomerate and interstratified trap,f tho Silurian rocks consist of gray and reddish sandy shales and coarso limestone bands dipping south at an angle of 44°. Tho direction of the coast is nearly east and west, and in proceeding to the cast- ward, tho dip of tho beds turns to south 30° west, dipping 45°, * See Journal Qool. Society, Vol. 4, and Acadian Geology, t See papers by tho author iu Frucoodiugs Qeological Society, 1843-4. Nova oj Nova Scotia* Society, SO that the series, though with some faults and flexures, is on the whole descending, and exhibits in succession to the rocks just mentioned, gray and dark shales, with bands and lenticular patches of coarse limestone, some of which appear to consist principally of brachiopodous shells in situ, while others present a confused mass of drifted fossils. Below these the beds become more argil- laceous, and in places have assumed a slaty structure, and occasion- ally a red colour. The thickness of the whole series to this point was estimated at 500 feet The dip then returns to the south, and the beds run nearly in the strike of the shore for some distance, when they become discoloured and oohraceous, and then red and hardened ; and finally, at Arisaig pier, are changed into a coarse reddish banded jasper, where they come into contact with a great dyke of augitio trap of carboniferous date. Beyond this place they are much disturbed, and so far as I could ascertain, destitute of fossils. The alteration of the beds extends to a distance of 300 yards from the trap, and beyond this in some places slaty cleav- age and reddish colours have been produced ; the latter change appearing to be connected with vertical fissures traversing the beds. In the lower or shaly portion of the Arisaig series, the charac- terstio fossils are GraptoUthus not distinguishable from G. cUnto- nensis, Leptoccelia (^Atrypa) intermedia, (Hall,) a new species closely allied to L. hemispherica of the Clinton group of New York, Atrypa emaceratiiy Orthis tcstudinaria, Strophomcna profunda, S. rugosa, Rhynconella equiradiata, Avicula cma- eerata, TentacuUtes, allied to or identical with T. distans, Ilelo poraa\\\QA to IT. frag ills. There are also abundant joints and stems of crinoids, and a Palccaatcr, the only one as yet found in Nova Scotia, which was presented to mo by Mr. Honey man, and has been described by Mr. Billings in the Canadian Naturalist un- der the name of P. parviusculm. These and other fossils associat- ed with them, in the opinion of Prof. Hall, fix the Geological position of these rocks as that of the Clinton group, the upper Llandovery of Murohison, at the base of the upper Silurian or top of the middle Silurian. In the upper and more calcareous part of the scries, fossils arc very abundant, and includo species of Cahjmene, Dalman'ia, Homalonotns, Orthoceraa, MHrchtHonia , Clidophorua, TelUnomya , and several braohiopods, among which aroDiacina tcnuilamelhita, Lingula ohlonga^ RhjfncoMlla quadricoata, It Sajfordi^ (Hall,) "■'5 .,!i Silurian and Devonian Rocks % U i I ( i J allied to R. Wihoni, R. nefflecta, Atrypa reticularis* alT found in the upper part of the Middle Silurian or in the Upper Silurian elsewhere in America. Most of the other forms are new species, descriptions of which will be found in Prof. Hall's paper appended to these notes. The general assemblage is on the whole like that of the Clinton, but is of such a character as to warrant the belief that we may have in these beds a series somewhat higher in position, and probably of Upper Silurian age. The new species GhonetcB Nova-Scotica is very characteristic of the upper member. On the whole we must regard the Arisaig series aB representing the upper part of the Middle Silurian, probably with a part of the Upper Silurian, a position much lower than that assigned to it in my Acadian Geology, which was, however, at the time, based on the opinions of the best palaeontologists who had examined specimens from these rooks. Unfortunately the Arisaig series stands alone, wedged between carboniferous and plutonic rocks, so that no opportunity occurs on the coast of verifying these conclu- sions derived from fossils, by the evidence of stratigraphical con- nection with newer or older Silurian deposits, and I have been un- able to devote sufficient time to this object to attempt to trace the beds in their succession or continuation inland. East River of Piotou. The next example of fossiliferous Silurian rocks known to mo is on the east branch of the East River of Pictou, and its vicinity, where these deposits rise from beneath the lower carboniferous series, forming the high ground on the eastern side of the river. The beds are here much altered and penetrated by igneous dykes, and are vertical, with very high southerly dips and N. E. and S. W. strike. They consist of coarse slates and calcareous bands resembling those of the upper Arisaig series in mineral character, and holding many of the same species, especially Chonctes Nbva- Scoticd ; but wo have here in addition a great bed of fossiliferous peroxide of iron, in some parts forty feet in thickness, and with ooli- tic structure ; but passing into a ferruginous sandstone, and nasoci. ated with slate and quartz rock. The ago of these rocks relatively to the Arisaig series, it is not easy to determine. The stratigraphi- cal evidence, though obscure, would place them in a higher position. The fossils are in a bad state of preservation ; but in so fur as • Also Sl»'o})hoinena corrugata. ore; 4 oj Nova Scotia* laris* alf the Upper as are new ill's paper I the whole to warrant somewhat The new tic of the spresenting ith a part at assigned t the time, d examined isaig scries ic rocks, so ese conclu- iphical con- ve been un- to trace tho town to mo its vicinity, irbonifcrous f the river, cous dykes, . E. and S. eous bands il character, nctes Nova- fossilifcrous id with ooli- , and nssoci. ts relatively itratigraphi- icr position, in so fur as they give any information, it coincides with the apparent relation of the beds. Similar ferruginous beds occur in the Clinton series, (the Surgent of Rogers) in New York and Cainada ; and as we shall find in the sequel, in a much higher position in the western part of Nova Scotia. On the whole I regard the beds seen at the East River of Pictou as belonging to the same line of outcrop with the Arisaig series, but as containing in addition to the upper member of that series, beds higher in the Silurian system, or perhaps Lower Devonian. CoBEQUiD Mountains. At the eastern end of this chain, in Earlton and New Annan, though the rocks are generally in a highly metamorphosed con- dition, fossils are found in a few places ; and in so far as I have been able to determine from very small suites of specimens, are those of the upper Arisaig series. From the apparent continuity of strike along this long salient line of outcrop, it seems probable that these fossils indicate the true age of the greater part of the sedimentary rocks of the Cobequid hills ; a conclusion confirmed by their similarity in mineral character to the altered equivalents of the Arisaig and East River series as seen elsewhere. The arrangement of the beds and their mineral contents in the central part of the chain, will be found noticed in my paper of 1849, already referred to. They are not known to contain beds of iron ore ; but have enormous vein-like deposits of spathic and specular iron associated with the carbonates of lime and magnesia, and run- ning with the strike of the beds. New Canaan. Between the East River of Pictou, and New Canaan in King's county, 100 miles distant, I know no Silurian beds with fossils ; and in the central part of the province these rocks disappear under tho carboniferous deposits. In tho hills of Horton and New Canaan they reappear, and constitute the northern margin of a broad belt of metaraorphic and pliitonio country, occupying hero nearly the whole breadth of the peninsula. The oldest fossiliferous beds seen are the fine fawn-coloured and gray clay slates of Beech Hill, in which Dr. Webster, many years since, found a beautiful Blcti/onema, the only fossil they have hitherto afforded. It is a new species, closely allied to I), retifortnis and 2>. gracilis of Hall, and will bo described by that palieontologist under the name of D. Wehsten, in honour of its discoverer, In ir SUunan and Devonian Rocks the mean time I may merely state that it is most readily charac- terised by the form of the cellules, which are very distinctly marked in the manner of Graptolithus, A portion of a frond is represented in Fig. 2. Fig. 2.— Part of frond otDictyonetM Wehsterij Hall, a, portion magnified. The Diclyonema slates of Beech Hill are of great thickness, but have in their npper part some hard and coarse beds. They are succeeded to the south by a great series of dark coloured coarse slates, often micaceous, and in some places constituting a slate conglomerate, containing small fragments of older slates, and occasionally pebbles of a gray vesicular rock, apparently a trachyte. In some parts of this series there are bands of a coarse laminated magnesian and ferruginous limestone, containing fossils which, though much distorted, are in parts still distinguishable. They consist of joints of crinoids, casts of brachiopodous shells, trilobites and corals. Among the latter are two species of A$- trocerium, not distinguishable for A. pyriforme and venustum of the Niagara group, and a HelioUtes allied to H. elegans, if not a variety of this species. On the evidence of these fossils and the more obscure remains associated with them, Prof. Hall regards these beds as equivalents of the Niagara formation of the New York geologists, the Wenlock of Murchison. Their general strike is N. E. and S. W. ; and to the southward, or in the pro- bable direction of the dip, they are succeeded, about six miles from Beech Hill, by granite. They have in general a slaty structure coinciding with the strike but not with the dip of the beds, and this condition is very prevalent throughout this inland metamor- phic district, where also the principal mineral veins usually run with the strike. The beds just described run with S. W. strike for a considerable distance, and are succeeded in ascending order by those next to be described. HI. — Devonian. . It is probable that Devonian rocks, in a metamorphosed state are ex consid clearlj margii and m At rocks stone to be Their I of Nova Scotia, 9 are extensively distributed throughout the distnets now under consideration ; but the only localities in which they have been clearly recognised, are along a line of outcrop on the northern margin of the hilly region westward of New Canaan. The first and most important of these exposures is at NiCTAUX. At this place, 20 miles westward of New Canaan, the first old rocks that are seen to emerge from beneath the New Red Sand stone of the low country, are fine-grained slates, which I believe to be a continuation of the Dictyonema slates of Beech Hill. Their strike is N. 30 to 60 £., and their dip to the S. E. at an angle of 72**. Interstratified with these are hard and coarse beds, some of them having a trappean aspect. In following these rocks to the S. E , or in ascending order, they assume the aspect of the New Canaan beds ; but I could find no fossils except in loose pieces of coarse limestone, and these have the aspect rather of the Arisaig series than of that of New Canaan. In these, and in some specimens recently obtained by Mr. Hart, I observe Orthoceras eleffantulum, Bucania trilohita, CornuKtes flexuosits^ Spirifer rugcecosta ? and apparently Chonetes Nova-Sco- tica, with a large Orthoceras, and several other shells not as yet seen elsewhere. These fossils appear to indicate that there is in this region a continuance of some of the upper Arisaig species nearly to the base of the Devonian rocks next to be noticed. After a space of nearly a mile, which may represent a great thickness of unseen beds, we reach a band of highly fossilifarous peroxide of iron, with dark coloured coarse slates, dipping S. 30" E, at a very high angle. The iron ore is from 3 to 4 J feet in thick- ness and resembles that of the East River of Pictou, except in containing less silicious matter. The fossils of this ironstone and the accompanying beds, as far as they can be identified, are Spirifer arenosus,* Strophodonta magnifica, Atrypa ungtdformis^ * There is ia the iron ore and associated beds another and smaller Spirifer as yet not identified with any described species, but eminently characteristic of the Nictaux deposits. It is usually seen only in the state of casts, and often strangely distorted by the slaty structure of the beds. The specimens least distorted may be described as follows : General form, semi-circular tending to semi-oval, convexity moderate : hinge line about equal to width of shell ; a rounded mesial sinus and elevation with about ten sub-angular plications on each side ; a few sharp growth ridges at the margin of the larger valves. Average dia- meter about one inch ; mesial sinus equal in width to about throe plicac tions. I shall call this species, in the meantime, S. Nictavensis. 10 Silurian ard Devonian Roch Strophomena depressa, and species of Avicula, Stllerophon, Favo- aiteSy ZaphrentiSj &c. These Prof. Hall compares with the fauna of the Oriskany sandstone; and they seem to give indubila* ble testimony that theNictaux iron ore is of Lower Devonian age. To the southward of the ore the country exhibits a succession of ridges of slate holding similar fossils, and probably represent- ing a thick series of Devonian btfds, though it is quite possible that some of them may be repeated by faults or folds. Farther to the south these slates are associated with bands of crystalline greenstone and quartz rock, and are then interrupted by a great mass of white granite, wlrch extends far into the interior and separates these beds from the similar, but non-fossiliferous rocks on the inner side of the mctamorphic band of the Atlantic coast. The Devonian beds appear to dip into the granite, which is in- trusive and alters the slates near the junction into gncissoid rock holding garnets. The granite sends voins into the slatci*, and near the junction contains numerous angular fragments of ultorcd slate. ... "Westward of the Nictaux River, the granite abruptly crosses the line of strike of the slates, and extends quite to their northern border, cutting them otFin the manner of a huge dyke, from their continuation about ten miI<^F; further westward. The beds of slato in running against this groat dyke of granite, change in strike from south-west to west, near the junction, and become slightly contorted and altered into gneiss, and filled with granite veins ; but in some places they retain traces of their fosHils to within 200 yards of the granite. The intrusion of this great nuiss of granite without material disturbance of the strike of the slates, conveys the impression that it has melted quietly through the stratified deposits, or that those have been locally crystallised into granite in situ, MOOBB RiVKR. At this place the iron ore and its aKsociatod bods recur on the western side of the granite before nuMitioiio*!, but in a slate of greator motamorpliism than at Nictaux, The iron is hero In the state of magnetic oro, but still h'jids fossil shells of the name species with those of Nictiiux. Bbar Rivrk. I On this stream, near tho bridge by whiolt the main roaf altered y crosses nortliern •oni their I of slato in strike sliglitly to veins ; Ihin 200 ' granite conveys itratifiod ' granite on the t»late of lioro in 10 same of Nova Scotia, a oroiies :)fiiHion of fossils. The iron ore is not seen, but there are highly fossil- iferous slates and coarse arenaceous limestone, and a bed of gray sandstone with numerous indistinct impressions apparently of plants. In addition to several of the fossils found at Nictaux, these beds afford Tentamlites^ an Atrypa^ apparently identical with an undescribed species very characteristic of the Devonian sandstones of Ga8p6, and a coral which Mr. Billings identifies with the Pleurodictyum probtematicum, Goldfuss, a form which occurs in the Lower Devonian in England, and on the continent of Europe. Westward of Bear River, rocks resembling in mineral charac- ter those previously described, extend with similar strike, but in an altered condition, and in so far as I have been able to ascertain, destitute of fossils, quite to the western extremity of the peninsula, where they turn more to the southward, and are as I suppose, repeated by a sharp synclinal fold, after which they are succeeded by the Atlantic coast series, consisting of quartzite and clay slate, with chlorite and hornblende slates at Yarmouth and its vicinity, and further to the S. E. of mica slate and gneiss. General Remarks. The above facts show that we can recognise among the partially metamorphosed sub-carboniferous rocks of Nova Scotifl, forma- tions ranging from the Middle Silurian to the Lower Devonian in(;lu8ivo ; but of a more argillaceous and loss calcareous charac- ter than the series occupying this position in the mainland of America. The principal ninssos of plutonic rock associated with these beds, and ospocially the granite, are of newer Devonian dale ; but there is evidence of igneous eruptions as far back an the beginning of the Upper Silurian, and of the continuance or recurrence of such aetii>n as late as the carboniferous period. lu atul near the non-calcareous Lower Silurian series, granile prevails, almost to the entire exclusion of other plutonic rocks. At a greater diHtaiico from these, the plutonic rocks penetrating tho Upper Silurian atul Devonian Hcries, thougli apparently of nearly the HMni'i ago with the granite, are principally syenite and gree»i- Btone. With respect to the g(Mieral arrangement of tlio formations, thdugh T cannot venture to speak with ctmlldcnco on this point, with reference to a district so much disturbed, aiul which I huvo been able otdy very imperfectly to explore, I may suggest, as at 12 Silurian Rocks of Nova Scotia* present the most probable arrangement, that represented in the little section attached to the map. The coast series wouM thus belong to an anticlinal, bringing up Lower Silurian rocks. On these, in proceeding to the north-west, rest middle and upper Silurian and perhaps Devonian beds in a metamorphosed condi- tion, which along the northern margin of the metamorphic dis^- trict rise again with an opposite dip, at Arisaig, East River, New Canaan, (&c., forming a trough, the middle of which, in the oast, is divided by a secondary anticlinal and filled with carboniferous rocks, but in the west is occupied with a great mass of granite into which the beds appear to have sunk in the direction of their dip. Beyond the northwestern edge of this trough, the Silurian beds probably again dip to the northward, but are hidden by carboniferous deposits, and reappear in another anticlinal with oast and west strike in the Gobequid Mountains. Rocks similar in character and relations to those above described are extensively distributed in the Island of Gape Breton and also in Now Brunswick, but I have no detailed knowledge of their distribution. The formations described In this paper, represent in age, and resemble in their state of alteration, many portions of the nictamorphosod Silurian and Devonian rocks of New England and Eastern Canada. In the latter, the relations of the intrusive granite and the middle and upper Siluri'in rocks ns de!>cribed by Sir William Logan, and as I have observed them in a few looali> ties, strikingly resemble the phenomena observed in Nova Scotia, I have no doubt that a detailed survey of these rocks in Nova Scotia and Cape Breton, would develop many curious and intri- cate disturbances, and might also ascertain the presence of mem- bers of the Silurian series, now supposed to bo absent, but which may be only oboeured by denudation. In the moan time local observers can do much to increase our knowledge of ihvm rocks by carefully collecting the few fossils that remain unohliteratcd in the senii-metamorpliic bods, and the above remarks may serve to guide such explorations, and to enable gcologiKts to npeak with more confidence than heretofore of the older palieozoio rucks of an important region of eastern Amoricn. Descrii Circl convej Seve lar im^ a flattc Thel valve ; | iatic of them. She apex Thi may b specie •^i ^ SI. nearl often midd mini oftc! dicli ther striu olosi L tho mai f Descriptions of New Species of Fossils from the Silurian Bocks of If ova Scotia. By Jamks Hall. 1. Crania aoa^i ,s. N. sp. Fig. 1. Circular or broadly Bub-ovu>, moderately convex, tbe greatest convexity near the apex ; apex obtuse. Several casts show a central elevated area, with strong muscu- lar impressions ; the more elevated portion being surrounded by a flattened border, which is radiatingly striate. These specimens are casts which appear to bo of the ventral valve; and the form of the muscular impressions is so chaiacter- istic of the genus that I can have little hesitation in thus referring them. 2. DisciNA TENUILAMBLLATA. Var. suhplana. Shell broadly elliptical, or suborbicular, externally depressed, apex subccntral ; surface marked by thin sharply elevated lamcllro. This closely resembles the Niagara species of New York, but may bo distinct. Should further examination prove it a distinct species, the name D. suhplana may be adopted. Fig. 2. Fig. 3. Fig. 1. ® M Fig. B. Fig. 4. 3. CnoNKTKS NovA-SooTicA. N. sp. Fig. 2. Shell semielliptical, width varying from once and a half to nearly twice the length. The ventral valve variably convex, and often showing a llattenod or slightly concave space down the middle of the shell ; cardinal margin ornamented by four or fivo minute spiiios on oiich side of the beak; cardino-latoral margins often a little wrinklo tie gibbous, ted strise. o refer this flj parallel; gibbous ; ght depres- id rounded, nterior end ice marked intric lines ss gibbous, I the direc- ting striffi. \ 25. MuROHisoNiA Arisaiobnsis. N. sp. Shell teretely conical, volutions about fivo, gradually increasing from the apex, rounded with a slight angulation or carina in the middle. The surface is unknown and the angular band on the volution is the only means of determining its generic rela- tions. This differs from any of the described species of Murchisonia from American localities. 26. Murchisonia aciculata. N. sp. Shell slender, very gradually tapering, volutions about six or seven, the last ones moderately ventricose, aperture elongate-oval or ovate, rounded at the anterior margin, columella plain ; volu- tions marked by a distinct band along the centre, and a sub-sutu- ral carina marking the upper side of the volutions; surface striated. Fig. 13. Fig. 15. D on vex and lall round- •emity, ex- Jtween the ibrupt de- led radiat- ndulations joncentric tta of the is slightly trie striae, this part 2?. HOLOPEA REVERSA. N. sp. Fig. 14. Shell small, sinistral ; spire depressed, volutions about three ; the two first small and gradually expanding, the last one rapidly expanding and ventricose ; aperture wide expanded ; suture im- pressed. Surface unknown. This shell has the general form of Holopea, but I have seen only a single specimen, which is a cast. It is remarkable and readily recognised from the sinistral spire. 28. Orthooeras punctostriatum. N. sp. Fig. 15. Shell slender, very gradually tapering, almost cylindrical; Septa distant about one third the diameter. Siph uncle central; section circular. Surface very finely striated with unequal undu- lating strise, the interstices between which, are punctee which are oblong indentations often becoming confluent. u Silurian Fossils of Nova Scotia, This species is remarkable for its extremely gently tapering form ; the fragment of more than an inch long, showing scarcely a perceptible diminution in diameter. There are twelve and a half chambers in the space of one incli. The surface markings arc peculiar, and among the species of the genus known to us constitute a distinctive character.* 29. CORNULITES FLEXU08US. VOr. ORAOILIS. This fossil resembles the one in the Clinton group of New York, but is somewhat more slender, and the annultitions a little more closely arranged. The specimens from the rocks of New York present some variation in form, and the comparative dis- tance of the annulations. None of them, however, arc so slender as the Nova Scotia specimens. I 30. HoMALONOTUS Dawsoni. N. sp. Fig. 17. Caudal shield somewhat parabolic, obtuse at the extremity, very convex, width at the anterior side greater than the length of the asis. from t deprcs on the ing sli and th abrupt curvin abrupt Fig. 16. * Tho Arisaig beds afford at least throe other 8pocii>a of OHhoceras. Cuo, tbo largest of tho throe, has a marginal iuilatud bipliunclu, and tbo sopta about ono-cighth of an iucli apart, fur n spochiion two inchua in diameter. It tapers very gently, and in all tho Hpeclniena found ia ellipti- cal in its cross section, it occurs in tiiu upper series. A second, found in tho lower scries, is marked witii strong annulations placed closely to- gotlicr. A third, occurring in tho upper sericn, and discovered ninco ♦he specimens were submitted to Professor Hull, is a very beautiful upocies, apparently new, but closely rosetnbling O, pcn'tri^ans^ Salter, of tho Lower Ludlow formation. It is cylindrictil, but sliglitly flattened • septa very convex and one-twentieth of an inch aiuirl in a Hpeclnu-n lialf an inch in diameter; siphunclo central. Kurfaco with sliglit rounded iinnulations from one-eighth io one-fourth of an inch apart, and covered with delicate transverse striio, scarcely visible to the naked eye, and about sixteen in a lino. Undur tlio microscope tlio striin appear as thin sharp ]mrallel curved rldgos, tho iipaces between being llnely granulated and wider than the ridges. I would uutuo this species O, dc^antutuin,— (Seo Fig. 10.)— J. W. U. Silurian JP'ossils of Nova Scotia* 80 tly tapering ing scarcely welvc and a ce markinirs mown to us )up of New ions a little cks of New arativo dis- so slender .17. cniity, very ngth of the Orthoceraa. clo, and tbc u incliua in d is uliipii. Ml, Cuund iu closely to« leered Binco boniitiful !«», Salter, fidttcnod • finuMi liair it rounded id cororod J <'ye, and !nr lis thill [riinitlatod Hluluin.— axis. Axis wider than the lateral lobes, distinguishable (in casts) from the lobes by a bending of the ribs and a scarcely perceptible depression along that line ; annulations abruptly prominent ; seven on the lateral lobes and nine on the axis, the anterior ones bend- ing slightly backward at the line of division between the axis and the lateral lobe ; each successive one bending more and more abruptly till the last one approaches a rectangular turn ; the whole curving gently forward at their extremities, and all terminating abruptly before reaching the margin. Behind the seventh annula- tion the axis is marked by two more annulations, leaving nearly one-fourth of its length smooth. This species is described from the casts and impressions of the caudal shield, so that the crustaceous covering is unknown. It is readily distinguished by the broad not prominent axis, the rect- angular direction of the annulations on the axis, and their abrupt bending at the lateral furrow. An impression of a few imperfect annulations of the body shows that they are strongly elevated, much more so than in any known American species. 31. Calymene Blumenbacuii. var. Caudal shield somewhat semicircular, axis very prominent, marked by about seven atinulations, lateral lobes marked by five ribs the four anterior ones bifurcating. Surface granulosc. The specimens are not sufficient to make any satisfactory determina- tions regarding specific diifereu(;cs. Fig. 11. rig. 18. 32. Dalmania Looani. N. sp. Fig. 18. Tlu) specimens are two or three imporfocteephalio shields, one pre<(orviiig the p:ilpobral lobes, and i)th(>rseoiisi!4ting principally of the i;ial)olla, with two or three parts of caudal shields. There is u fra<;ment of a cheek which may be of this spicii'S. Cophalio shield soMunvhat scniicireular. Glabella ovate, wider in front and truncate behind, depri^ssed convex ; occipital ring narrow, pro- minent ; occipital furrow bending a little forward in the middle and curving gently buckwiuU in the middle uf each Hide, uud '*ym Silurian Fossils of Nova Scotia, again turning forward ; posterior furrows narrow and sharply im- pressed, each one extending about one third across the glabella and curving forward at their outer extremities ; central furrow linear, obscure, having a direction transverse to the axis ; anterior furrow obscure oblique to the axis, linear, extending to the margin of the glabella a little forward of the eye ; frontal lobe regularly rounded anteriorly. A fragment of a cheek in the same associa- tion is broad, produced posteriorly in a short strong spine, and marked by a broad sub-marginal groove. Caudal shield somewhat semi-elliptical, convex, acute behind, axis very prominent, rounded and marked by about eight annulations, which are gently curved backward at the extremities ; lateral lobes with six simple flat- tened ribs which terminate in a tliickened border, and separated from the axis by a strongly defined furrow ; extremity abruptly pointed. The glabella of this species more nearly resembles Phacnps in the general form and faintly impressed furrows, of which the pos- terior one is conspicuous. The form of the palpebral lobe, and the absence of tubercles at the base of the glabella, together with the form of the caudal shield, ally it with Dalmania, and it may bo compared with J). PhilUpsi of Barrandc, but has a more pointed euudiil shield, and the oliook, if correctly referred, is prolonged in a posterior spine.* 33. Beyricuia PUSTiTLosA. N. sp. Fig. 19. Valves unequally somi-oval, a little more than once and a half OS long as wide ; surface marked by three prominent ridges ; cen- tral, anterior, and posterior. The central one is a single oblong oval tubercle which is directly transverso to the dorsal margin and a little nearer the anterior side. The anterior ridge consl-sts of a single highly elevated, rounded or papillose tubercle near tlie dor- sal margin, and an elongated elliptical tubercle placed obliijuely near the antero-vontral margin, and in older Hpecinions sometimes swelling and spreading over the margin. The poHtcrior ridgo rises nea" the dorNul margin, and making a Hlightly br(»iuler curve tlian the posterior end of the valve appritiielu's the ventral margin at the centre : the ridge is high and angular with a small prominent • Atluclic'tl to a friignu'iit ofoiio of theso trilobllcs ia n sniiill Sinrorbit. It 1h (U'xtrnI, willi two to tlirco turns, and rouiidcil coucontrlo wrluklol on tho liisl whorl.— J. W. D. tubercle fpine-lill de is si Its contl lower ej gins wij This den, as Bpecim<| at its is marl anterioi in our tubercl shown pear to of surf J5. tvhi ''"'wm Nca nearly roaehi to tho scarce tremii of th( on th its pa thick M short olo n vent (Voni Silurian Fossils of Nova Scotia* 27 1 sharply im- the glabella ntral furrow xis; anterior the margin bo regularly lame associa- spine, and Id somewhat snt, rounded sntly curved simple flat- d separated ity abruptly Phacnps in ich the pos- 1 lobe, and ,'cther with d it may bo i>ro pointed :olongcd in 9. nnd a half Iges; con- kIo oblong uargin and HHists of rt r the dor- obli(juely 'Oinictimes ior ridgo dor curve id margin romlncnt 'Sfiirorbii, I wriukloi tabcrclo at the dorsal extremity, and from four to six smaller ■pine-like tubercles along its curve. The central ridge or tuber- cle is separated from the lateral ridge by a distinct furrow, and its continuation from the base of the tubercle passes between the lower ends of the two lateral ridges. Ventral and lateral mar- gins with a narrow thickened rim. This species resembles very neprly the />. tuherculata of Klo- den, as described and figured by Mr. T. Kuport Jones. In our specimens the dorsal ongles are more rounded ; the posterior ridge at its base is never extended beyond the middle of the valve, and is marked on its crest by several small spine-like tubercles. The anterior ridge is usually more extended along the ventral margin in our specimens, aud the furrow is better defined, while the tubercles are never fiattened above or overhanging the base as shown in the European specimens. Smaller specimens, which ap- pear to be the young of this species, present some slight variations of surface markings, but show loss difibrenco than the young of B. tuherculata. Q e Fig. 10. Fig. 20. :m oi. Bjsyrioiiia eqilatera. N. sp. Fig. 20. Nearly equilateral, very convex, marked by three smooth or nearly smooth ridges. The central ridge is an oblong tubercle reaching from near the dorsal margin a little more than half way to the ventral margin. The posterior ridge is a little larger, but scarcely differing in form from the anterior one, its ventral ex- tremity terminating beneath or a little in advance of the middle of the central tubercle. The furrow is narrow but well defined on the two Hides of the central tubercle, and becoming shallow in it« passage to the marginal furrow ; ventral and lateral margins thickened. 35. Leperdita binuata. N. sp. Minute sub-ovate, anterior end narrow, dorsal lino one-third shorter than the length of the valve ; an extremely minute tubcr- olo near the anterior end. Centre extremely convex or ventricoso ; ventral margin near the poHterior end a little ninuous, or indented from the inner side. Surface smooth under au ordinary luus. 88 Silurian Fossils of Nova Scotia, Two specimens only of this species have been observed, both of them having the same dimensions. 36. Tentaculites distans. var. The specimens under examination do not present any important points of difference from those of the Clinton group in New York. In the Nova Scotia specimens there are numerous annulations near the apex, which are not observable in the New York speci- mens. 37. Helopora fraoilts, var. acadiensis. The specimens under examination offer no very important dif- ference from those in New York, and as the Nova Scotia examples have been more or less compressed and worn, they are scarcely in a satisfactory condition for nice discrimination. All the above fossils belong to the Arlsaig series of Mr. Daw- son's paper. Nos. 4, 10, 30, 36 and 37 appear characteristic of the dark and olive shales of the lower member, in which are also Stroplwmcna profunda, S. rugosa, Orthis tcstudinaria, Atrypa emacerata, Rhyncondla cqniradiaUiy GraptoUthus CUntoncnsis, and crinoidftl columns ; also a Modiolipsis allied to M. suhcari- natus. The remaining species are in the coarse limestone and reddish shale of the upper member, in which are also Strophe- mcna corrugata, Atrypa reticularis, Rhyncondla. ncghcta, Lin- gnla ohlonga, Bucania trilohita, and a Chatetcs or Stcnopora similar to that of the Clinton formation. Cornulitcs fcxnosm is almost the only species which occurs equally in both groups of bods. Some of the CUdophori are also found in both groups. :■% erved, both of njr important n New York. ■ annulations r York speci- 18. oportant dif- >tia czanipleg e scarcely in 3f Mr. Daw- acteiistic of licli are also rid, Atrypa yiintoncnsis, M. suhcari' lestono and «o Stropho- jlccta, Lin- Stcnopora Cexuoms is l» groups of groups. ■.tW I