AAA •*••? t A38 9 / NOTES ON", AND THR PRBCISK GEOLOGICAL HORIZON OF SIPHONOTRETA SCOTICA, DAVIDSON. BY HENRY M. AMI, M.A., F.G.B. (Read March Srd, 1887.) At the Montreal Meeting of the American Association for the Advancement of Science in 1883, Mr. .1. E Whiteaves, Piilfeontologist, &c., to tlie Geological Survey of Canada, read a communication or paper before the Geological Section, in which there was recorded for the first time on this continent the occurrence of a beautifully fringed, or spincse brachiopod, which, from specimens sent him, Dr. Thos. Davidson, the eminent autliority on the Brachiopoda, had recognized to be referable to a form wliich he himself had desciibed as Si- phonotreta Scotica. The specimens thus referred to de Veineuil's genus Sip/ionotret'ji had been collected by Mr. J. W. H. Watts, of the Ottawa Field-Naturalists' Club, and that gentleman had handed them to Mr. Whiteaves and subsequently presented them to the National Mr.seum at Ottawa where they are now exhibited in the cases. 'Ihe specimens iQ question liad been obtained from blocks of impure limestoiie lying near Mr. Watts' residence at Cummings' Bridge, near Ottawa, and were said to have come out of a well sunk by the same gentleman on his property. There was but little doubt, both from the lithological aspect of the rock containing the specimens of Siphonotreta and other fossils found an this property, and from the facies of the included fauQa, that the measures whence they came were referable to the Utica Formation. For some time, however, a certain amount of doubt was entertained by a n»imber of palieontologists as to the precise geological {)08ition of the interesting form under consideration ; but, from recent investigations made with the special object in view of clearing this point, the writer, in conjunction with Messrs. McConnell, Hayter and other members of tflk .'Otfij'wa F'dd-Nr.tv.raliRt'i' Cbxb has made a ',"4 ' ',. . . ■'...* ^number of excursions* aUiiing whic'h Mpf^ciinienV • of tliis beautiful shell were collected. *'/*/• .'*.''' •" - - ,»,»■- 51199 Ill order to ascertain definitely the tr»ie horizon cA the Siphonotreta in question, it "was necessary to find it in situ, and further to obtain from the same had or beds in which it occurs as niuny 8i)ecie8 of fossils as [lossible, in other words, determine what were its eonten>porarie» It had l>een previously [)ointei] out that the lowest n^easures of the Utvca formrtti<.'n about Ottawa consisted in a series of in>pure bands of limestone, at times slightly dolomitic and intei-stratified with black brittle bituminous shales all abounding in fossils. (See Geological Hej)ort, Transactions Ottawa Field- Naturalists' Club, Vol. I. No. 4^ p. 66 ; also Vol. II, p. 347). The close resemblar.ce in lithological character between the specimens sent to' Dr. Davidson by Mr. Whiteaves and the rocks constituting the lower poj'tion ot the Utica formation where it crops out along the right bank of the Rideau River, opposite the Rifle Range, near the rapids, was such as to warrant a careful search for SiphoaotreUt in that locality. Atttr a somewhat careful search on the jwrt of those members of the Club above men- tined, a goodly number of s|)ecimens of this interesting species were found at tl>e rapids along with other forms to bo mentioned later on. The precise bed in which Si^honotreta Scotica occurs, is that band of impute bituminous limestone, black or ids or slight fall, giving the i)eculiar orograi)hic .k-«pect to that portion of the rivei* which it jwssesses and dividing the smooth flowing water above this point stictching on to near Hurdman's Bridge from the rapid running waters below. The following is a section of tlie measures of the Utica formation exjtosed at the head of the rapids opi>osite the Rifle Range, and in- clude.*? the zone of Siphonotreta Scotica. The middle and up[)er measures of the Utica have been denuded away, esjx'cirtlly during glacial times, and the uppermoe»t beds of the section are capped with Post- Tertiary de()08its made up tor the most part of debris of the * till ' and Saxicava sand and as80oi*ted gcayel. foriOitiorjfi with * erratics ' in abundance, the •'•Jtdi>^jbeei>Vi^bw^taway in latter times. The section is given, iij.de^iyliAg oiadtr.:-^ ,«, ,• •• CHAUACTKR oF BEDS, THE THICKNESS, &.C. These upper measures consist of very soft, brittle and friable bituminous shales holding Triarthrus Bccki, Green and other fossils. Band of hard compact impure limestone teeminaj with the remains of Conularia Trentonensis, Hall, and holding also Zygo»pira Ileadi, liill, Leptmna sericea, Sow. Orthis testu- dinaria Dal, Calymene senaria, Con., Kc, &c. Zone of Siphonotreta Scotica. Band of black impure bitu- minous limestones gradually passing into a series of calcareo- argillaceous shales, at other times compact and Ineaking with a conchoidal fracture, holding abundance of fossils. (See lists.) (Shales.) Thirty inches. (Limestone) One inch. (Limestone.) Zone of Siphonotreto. Varies from eight to twelve inches. Black and brittle impure (calcareo-argillaceous) shales, bitu- minous and holding the remains of Aaaphun CanaJsHaif, Chapman, Kc, (Shales.) Band of impure limestone. Shales, very bituminous and brittle. Band of impure limestone. Brownish-black beds of shales, very brittle and bituminous. Two bands of an irregular and unevenly bedded nodular limestone containing Orthocerata and other fossils but poorly preserved; limestone dark and seoiewliat bituminous. (Limestone.) (Shales.) (Limestone.) (Shales.) (Limestone.) From the band of impure limestone holding Siphonotreta the followins: species of fossils have also been found intimately associateu therewith : — 1. Batostoma erraticum Ulrich, 2. Lingula curta, Hall. 3. " elongata, Hall. 4. " quadrata, Eichwald. 5. Leptaena sericea, Sowerby. 6. Strophomena alternata, Com ad. 7. Orthis testudinaria, Dalmau. 8. Zygospira Headi, Billing?. 9. ** modesta, Say. 10. Zygospira (probtvbly a new form). 11. Conularia Trentonensis, Hall. 12. Asaphus Canadensis, Chapman. 13. ♦• platycephalus, Stokeg. vel megistos, Locke. 14. Calymene senaria, Conrad. 15. Beyrichia oculifera. Hall. 16. Leperditia cylindrica, Hall. A mere glance at the fauna which thus characterizes the zone of Siphonotreta Scotica in America is sufficient to indicate that the measures whence they came belong to the ITtica Formation, in the upper portion of the Cambro-SiluHan or Ordovician System. A single liand specimen showed the following interesting association of species : — ..... . ... 1. Siphonotreta Scotica, Dav. 3. Zygospira Headi, Bill. 2. Leptaena sericea, Sow. . 4. Asaphus Canadensis, Chap. From specimens obtained at the head of the Rifte Range R ipids along the Ridean River by the writer and from those of tlie Niitional Museum collection kindly placed at the disposition of the writer by Mr. Whiteaves, the following notes have been gathered : — Specimen No. 1, — Collected at the rapids along the Ridean River, op|)osite the Rifle Range, in Gloucester. Collector H.M A., 188(1. This si>ecimen agrees well with the beautifnl and cleai- description given by Dr. Davidson in his *' Supplement to the British Silurian Brachiopoda, 1882 1884, p. 217," and only slight variations such as might be merely local can be observed. The dimensions of the shell are as follows: — Length., twelve and ahalf millimetres; breadth, eleven millimetres ; height, measured at about one third the distani-e from the beak to the anterioi extremity, two millimetres. Length of the longest spines, seen along the anterior margin, three millimetres. Specimen No. 2. — Collected by Mr. J. W. H. Watts on his property, Cummings' Bridge P. O., Ont., near Ottawa City, 1883. This specimen exhibits tlie spines all around the outer margin of the valve from near the beak on one side round the front margin and near the beak on the other side- These spine«, the longest measured as yet, gave three and a half millimetres, or one and a half lines in length. In the oentrp of the umbonal region where the valve rises abruptly from the beak near the latter there is a clearly defined sintis or groove ex- tending only a short diptance anteriorly and dying out on the gently convex or ai-ched valve. This feature is also present in the next. Specinen No. 3. — Collected by Mr. J. W. H. Watts at the same locality as No. "i. ... A very typical example of the species indeed, whose length is twelve and a half millimetres (6 lines) and breadth ten and a half millimetres (5 lines). 1'he height of the valve is two millimetres but the spines being partially or wholly imbedded in the matrix their length has not been ascertained exactly. The three specimens above referred to, as mentionel before, agree well with Dr. Davidson's Scottish form Siphonotreta Scotica ; never- theless as it may possibly happen that the Canadian form exhibits the few [)oints of variation constantly, thjo varietal designation of Si- 5 phonotreta Scotica var. Canadensis now proposed, may perhaps not be entirely deemed inapf«ro))riat«. The spines in the Canadian 8|>ecidaens examined so far are exceedingly minute and ntimerous, narrowly cylindrical, pointed and smooth for the most part, and somewhat broad and thickened at the base. Kven under a high power of a microsoope the spines appear to be smooth, no anuulations being visible, whilst irregularly distributed punctures at times appear to be present — these aie perhaps due to the mode ot tossilization. The number of spines round the outer margin of specimen No. 2. (supra) has been roughly estimated at over three hundred, forming only one of the many rows of " adpressed spines " ranging from beak to beak round tlie anterior front of the shell. [t may not be d«eme) and the Crustacea are taken from the admiral>le " Monograph of the Siluri»:i to Canada all italicised. BRACHIOPODA. 1. Lingula quadrata, i'ichwald. 12. Orthin tfxtudinnria, Dalmau. 2. " Ranisayi, Salter. 13. " coiifinis, Salter. 3. Discina perrngata, McCoy. 14. " biforata. Sohlothein. 4. Acrotreta Nicholsoui, Dav. 15. " turgida, McCoy. 5. Lepttrna scriccri, Sow. 16. Strophomeua rhomboidalis, Wilckens. 6. ♦' teiuiicincta, MoCoy. 17- " Imbrex, Paiider, var. 7. " Youugiaiia, Dav. ' 18. " ^xpaiisa, Sowerby. 8. " Grayiic, Dav. ,19. " retroflexa, Salter. 9. Lepta?iia Ethorilgei, Dr.vr. 20. Khynchonella Balcletchieiisis, Dav. 10. (?) Orthis unguis, Sdw. 21. " I'eachii, Dav. 11. Orthis Sowerbyiaiia, Dav. 22. " Scotica, Dav. 6 CRUSTACEA. 1. Calymene Blumenbachii Brong. 6. Illaenus Bowmani, Salter. 2. Broiiteus sp. (large form). 7. " Rosenbergi, Eichwald. 3. Cheirurus gelasiuosus, Portlock. 8. Lichas Hibernicus, Portlock. 4. Encrinunxs puiictatus, Briimiich. 5. Eucriimrus puiictatus var. areuaceus, Salter. The association of Siphonotreta Scotica, Dav., has thus been given both as regards its Canadian and European contemporaries. There are no doubt a number of other forms occurring throughout the section at the Rapids, in Gloucester, not mentioned, which would swell the list considerably, but sulisequent researches will help in ascertaining their precise affinities and lead to other forms being found. There remains much work, however, to be done in ascertaining the internal characters of this pretty little spinose brachiopod which in Scotland and Canada used to flourish in the old Caml)ro-Silurian Seas. Should any member of the Club find any specimen or specimens of Siphonotreta Scotica or of its Canadian variety which would throw additional light and show the muscular and other impressions of the interior of this shell belonging to the division of the Tretenterata, he or she would be conferring a favour to Science by contributing the same in the Club's Transactions or elsewhere. JST, Decenil)er, 1887, :o:- ' *