Downloaded from http://jgslegacy.lyellcollection.org/ at Ohio University on June 21, 2016 1869.J ~v~Cx~--CORA~ FXWXS oF W~STER~ ~VR0~E. 51 those adopted by the President. This would be evident, so far as concerned Pterodactyles, from a work on Ornithosauria which he had just completed, and which would be published in a few days. Mr. ]~T~.RIDa~. stated that the dolomitic conglomerate in which the Thecodont remains occurred near Bristol was distinctly at the base of the Keuper of the Bristol area, being beneath the sandstones and marls which underlie the Rheetic series. There were no Per- mian beds in the area. He regarded the conglomerates as probably equivalent to the Muschelkalk. It was only at one point, near Clifton, that the Thecodont remains had been found. Prof. HvxT,~Y was pleased to fifid that there was such a diversity of opinion between Mr. Seeley and himself, as it was by discussion of opposite views that the truth was to be attained. He accepted Mr. Etheridge's statement as to the age of the Bristol beds. 2. The PHYSICAL G~.0GR/~PItY of W~.ST~RI~ :EuRoP~ during the MEso- zoic and CxINozoIc periods elucidated by their CORXT. Fxv~As. By P. MAR~r~ Du~cx~, M.B.Lond., F.R.S., Sec.G.S. CONTENTS. I. Introduction. VIII, Some Genera of Reef-Faunas, II. Deep-sea and Abyssal Corals (ex- ancient and modern. isting). I:~ List of Coral-sea Conditions in III. Exceptions. different Periods IV. Littoral Corals (existing). X. Corals and Coralliferous Deposits, V. Reef-makingCorals,&e.(existing). in consecutive geological pe- VI. Exceptions. riods. VII. Exceptional Relations of the two XI. Conclusions. Faunas. 1. INTRODUCTION. T~. physical conditions which determine and accompany the ex- istence of coral reefs, and the natural history of those vast aggrega- tions of species of Madreporaria, have been sedulously and successfully studied ever since Darwin and Dana published the facts and theories which aroused the scientific world to a sense of their importance to geological reasoning. The physical geography of the Indo-Pacitlc and West-Indian seas has been investigated with as much care as the zoology of those marine banks which, fashioned by coral polypes, form a nidus for the existence of vast numbers of Invertebrata, fish~ and birds. Nothing has been more satisfactorily determined than the scheme of the production of reefs, and the system of species- grouping that obtains in them. The dependence of the coral polypes upon certain definite external conditions is as well understood as is that of the myriads of mollusca upon the flourishing state of the reef-builders. The dredge 9has done much to show the characters of the corals in the shallows and moderately deep seas of reef areas ; and the species and genera fre- quenting them have been distinguished from those peculiar to the The late Mr. Christy gave me the results of his dredgings of Corals between Cuba and Jamaica Pourtales, Bull. Mus. Harvard Coll. nos. 6, & 7. Downloaded from http://jgslegacy.lyellcollection.org/ at Ohio University on June 21, 2016 52 "PROCEEDINGSOF THE GF,OLOGICAL 8OCTET1r. [l~ov. 24, reefs and lagoons. The bathymetrlcal disposition of the species of the reefs has been studied with good results * ; and it has become evident that there are natural-history provinces of ~[adreporaria, the most distinct being those of the Caribbean sea and the Indo-Pacifie Ocean. Careful and systematic dredging in the ~editerranean, the North Sea, and the Atlantic has proved the existence of a deep-sea and abyssal, as well as of littoral coral faunas, which have nothing in common with true reef forms. The anatomic~ construction of the majority of the deep-sea corals differs from that of the reef-builders and the species inhabiting shallows and lagoons in the neighbourhood of reefs. There are evident distinctions in the methods of growth and gemination. The physical conditions of the areas are as diverse as the genera and species inhabiting them. The corals of the West Indies, Bermudas, Indo-Paei~e, South Sea, China seas, and Red Sea, form one series ; and the species inha- biting the deep water and littoral tracts off some portions of the great continents are included in a second. The species of the first are infinitely more numerous than those of the second series, and there is no difficulty in distinguishing them. The external condi- tions which accompany both series are tolerably well understood: and the instability of reef areas is comparable with the stability of the deep seas beyond their range, l~ecent researches have proved that vast districts of the deep-sea bottom are uncoralliferous, and that others maintain much coral life at immense depths t. Whilst the natural history of the existing Madreporaria has been carefully studied, the paleontology of the coralliferous strata has been by no means neglected. Monographs, properly illustrated, have described the fossil corals of certain districts ; and systematic works have treated of the fossil Zoantharia as a whole. Reuss's descriptions of the corals of the Oberburg in Styria, Castel Gomber~o in the Vieentin, and Gosau in Austria**, are as exhaustive as the labours of d'Achiardi w Seguenza I1, De Fromentel 82and, last, but not least, of MM. Milne-Edwards and Jules Haime". The description of the fossil corals of the Mesozoic and Cainozoie strata of Great Britain has been completedtt, and the relation of the successive coral faunas in them to those of the equivalent formations of the Continent has been studied and noticed. In fact, the litera- ture of the coral formations is sufficiently advanced for some gene- ralizations to be attempted between the peculiarities of the past and present faunas. 9 Miehelottiand Duchassalng, ~Iem. dell' Acead. Torino, 1865. LyeU,Prin- ciples of Geology, 1868. t Reports on deep-sea dredging (Proc. Roy. Soc. 1869), Carpenter, W. Thom- son, Gwyn Jeffreys. .+ Essays in Wien. Akad. Denkschr. w Coral. Foss. in Mere. della Soc. Ital. di Sci. Nat. II Coral. Foss. in ~Iem. della Reale Accad. Torino, Serie ii. tomo xxi. p. 399. 82Polyp. Fossiles. 9~ Pal. Soc. Brit. Foss. Cora]s. Hist. Nat. des Corall. tt Duncan, Pal. Soc. Brit. Foss. Corals. Downloaded from http://jgslegacy.lyellcollection.org/ at Ohio University on June 21, 2016 1869.] DV~CX~--C0~AL ~AUSAS OF WZST~X~ XVR0~V,. 53 There has been much progress made in connecting the phenomena of existing reefs with those of the past, with the idea of establishing propositions upon which geologists could reason. Many years since, Lieut. Nelson * proved that sediments which were supposed to be characteristic of Oolitic and Cretaceous rocks were imitated around the Bermudas ; and of late years much has been written upon coral limestones and marls, and the metamorphosis of coral rocks into dolomites has been hinted at t. Speculations have also been published respecting the influence of the subsidence of reefs, their becoming covered up with deep-sea deposit, and the creeping of deep seas over littoral tracts and land upon the notions of contemporaneity $. In 1863 w the similarity in general arrangement of the Mio- cene reefs of the West Indies to those now encircling many of the islands was announced; and it was stated that the species of the old reefs could be divided into those which lived amongst the boiling surf, in the quiet lagoon, along a barrier reef, and in deep water close by. The raised reefs of San Domingo were shown to link the specialities of existing reefs to those of the past; and an ex- amination of still older coral formations on the same area indicated that even in the Lower Cretaceous rocks there were proofs that the same external conditions and the same grouping of coral forms were as characteristic of the ancient as of the Caribbean reefs. Again, the study of the Sicilian and Crag deposits proved that the former seas, out of the range of reefs, had coral species representa- tive of those now living in deep and abyssal water, and occasionally just below low spring-tide mark. Moreover many English geol~sts II had shown that coral reefs formed parts of Palmozoic and Oolitic landscapes; and Stoppani 82 proved that the Azzarolan banks were formed by a branching Ma- dreporarian. With these facts and theories at hand there is a demand for their utilization in some common inquiry; and this communication is an attempt to explain some of the former physical conditions of Western Europe by comparing the fossil coral faunas with the existing ~*. It commences with a notice and a description of the typical species of the coral fauna of the deep and abyssal seas which bound con- tinents remote from reef areas; and then follow remarks upon 9 Trans. Geol. Soc.2nd ser. vol. v. t S. P. Woodward held this opinion. (Geol. ]Kag. vol. i. "Review of the Dolomite l~ountains?') Duncan, Report on Brit. Foss. Corals, Brit. Assoc. 1868, 1869. w Quart. Journ. Geol. Soc. vol. xix. p. 406. II Ramsay and Murehison ; Wright, Cotteswold Club, 1868. 82Pal. Lombard. 9* Some theoretical considerations bearingupon this communication will be noticed in :--Description Toss. Corals of the West India Islands, 1863. Repo~t on British Fossil Corals, read at Norwich, 1868, and ]~xeter, ]869. PM~eontograph. Soc. Supp. Brit. Foss. Corals, 1865. Tertiary (written 1864). Since this essay was read the specimens of corals dredged up in the 'Porcupine' expedition have been examined by me, and Count Pourtales has sent me most of the types of the deep-sea coral fauna off Florida and the Itavannah. I still find that the deep-sea corm faunas differ essentially from those of corM-reef areas.