Aug. 26, 1875] 



NATURE 



357 



Gyrolepis, Sargodon, and Cetatodus, with bones of Plesitsaurus 

 and Ichthyosaurus . It is the teeth of Ceratodus, or homed teeth, 

 that have made Aust Cliff famous ; and more than 400 different 

 forms have been described. Mr. C. T. Higgins made the finest 

 collection of these remains, which has been purchased for the 

 Museum, and forms one of its rarest treasures. When these 

 homed teeth, so called from the prominences they exhibit, were 

 first described by Agassiz, the living species of this genus was 

 not known ; it is now ascertained that it lives in the Mary, 

 Dawson, and other rivers of Queensland, and is called by the 

 natives " Barramanda." The Ceratodus is very nearly allied to 

 the Lepidosircn, is cartilaginous, a vegetable-eater, and, like the 

 Lepidosirtn, lives in muddy creeks ; during the hot season it 

 buries itself in the mud, whence it is dug up by the natives, its 

 retreat being discovered by the air-hole through which it breathes ; 

 its nostrils are placed in the inside of the roof of the mouth. 



A very interesting paper on Ceratodus Fosteri (the specimen in 

 the Museum) by Mr. Stoddart, F.G.S., will be found in the 

 " Proceedings of the Bristol Naturalists' Society," vol. i. 

 p. 145. 



The Lias, which succeeds the Avicula contorta beds, presents 

 a remarkable contrast to them, and shows how much the life- 

 conditions of every age depend on the physical agents that sur- 

 round it. Two groups of animals appeared in great force in the 

 Liassic sea — Ammonites and Reptiles. 



The Ammonites of the Lower Lias beds, A. angiilatus, A. 

 Bucklandi, A. Coitybcari, and others, attained a large size ; and 

 the middle and upper divisions of the same formations were all 

 characterised by different species that marked horizons of life in 

 these divisions. Associated with the Ammonites a large as- 

 semblage of other Mollusca are found, as Gryphtra, Lima, Uni- 

 cardium, Pholadomya, Cardinia, Hippopodium, Pleurotomaria , 

 and a profusion of Belemnites and large Ahmtili. 



The Reptiles were very large, as you can see by the fine speci- 

 mens on the walls : Ichthyosaurus and Plesiosaurus were the 

 dominant forms of this class ; and Pterodactyles with expanded 

 wings performed the part of birds on the dry land of that era ; so 

 that the air, the estuary, and the ocean had each separate forms 

 of Reptile life in the Lias age. Another change of conditions 

 introduces us to new forms in the Lower Jurassic sea. A large 

 number of species of Conchifera and Gasteropoda crowd the 

 shelly beds of the Inferior Oolite ; and new forms of Ammonites 

 appertaining to groups entirely different from those of the Lias 

 are found in abundance in Dundry Hill. In addition to the 

 Mollusca we find many beautiful forms of Echinodermata, and a 

 large collection of reef-building corals in the upper beds of the 

 hill. Nothing gives us a clearer insight into the fact that all fossil 

 species had a limited life in time than the distribution of the 

 Echinodermata of the Jurassic strata, inasmuch as these animals 

 possess a skeleton of remarkable structure, on which generic and 

 specific characters are well preserved ; they form, therefore, an 

 important class of the Invertebrata for the study of the life-history 

 of species in time and space ; and this Table of the stratigraphical 

 distribution of the Jurassic Echinodenns which I now exhibit 

 reduces these observations to a practical demonstration. 



The Oolitic rocks were formed in a coral sea analogous to that 

 which rolls its waters in the Pacific between 30° on each side of 

 the equator. In the Lower Oolites are four or five Coral forma- 

 tions superimposed one above another, with intermediate beds of 

 Mollusca. The Middle Oolite is remarkable for the number and 

 extent of its coral reefs, and the Upper Oolite for those found in 

 the Portlandian scries. 



The Jurassic rocks were accumulated as sediments or shore- 

 deposits under many changes of condition ; and the idea of a 

 slowly subsiding bed of the coralline sea gives us, perhaps, the 

 nearest approach to what appears to have prevailed. 



The Jurassic waters were studded with coral reefs, extending 

 over an area equ.il to that of Europe, as they stretch through 

 England diagonally from Yorkshire to Dorsetshire, through 

 Ffance from the coast of Normandy to the shores of the Medi- 

 terranean, forming besides a chain winding obliquely through the 

 Ardennes in the north to Charente-Inferieure in the south, in- 

 cluding Savoy, the Hautes-Alpes and Basses-Alpes, the Jura 

 Franche-comte, the Jura chain of Switzerland throughout its 

 entire length from Schaffhausen on the Rhine to Cobourg in 

 Saxony, and along the range of the Swabian Alps and Fran- 

 conian Jura. Throughout all this widely extended Oolitic region, 

 coralline strata were accumulating through countless ages by the 

 living energies of Jurassic Polyp ifera, as all the Madreporic lime- 

 stone beds in these formations are due to the life-energies of dif- 



ferent species of Anthozoa ; and were we to venture to estimate 

 the lapse of time occupied in the sedimentation of the coral- 

 ligenous Oolites by what we know of the life-history of some 

 living species, we should find good reasons for concluding that 

 the Jurassic age must have been one of long duration. It is not 

 the mere coralline stmcture per se that is due to Polyp-life, but 

 the entire mass of Oolitic limestones are the products of the same 

 vital force ; for there could be no doubt in the mind of any com- 

 petent observer who carefully examined such a rock as that in 

 my hand that it was a mass of coral secreted by a Jurassic polyp, 

 and that the Oolitic limestone which surrounds the coral stem is 

 the product of a portion of a wasted reef which had been broken 

 up, ground into mud, and constituted the calcareous paste that 

 had coated particles on the shore, and formed by the roll of the 

 waves the oolitic globules which were afterwards cemented by 

 calcareous waters, and the whole transformed into the rock we 

 call Oolitic limestone ; and thus the genesis of the Oolites was 

 due to the vital energies of the myriads of polyps that lived in 

 the Jurassic seas. 



The reefs that remain are merely fragments of what had 

 existed ; and those that have disappeared furnished the calcareous 

 material out of which the Oolites of subsequent formations have 

 been built up. 



I have to thank my old friend Mr. Etheridge for the valuable 

 notes he has supplied on the Mendip Hills (which he knows so 

 well), and to Mr. M'Murtrie for his excellent notes on the 

 Radstock district (which he has so long explored), and to Mr. 

 Stoddart for kindness and assistance in many ways. Without 

 their friendly co-operation it would have been impossible for me 

 to have given so much exact information on the stmcture of the 

 interesting and complicated region in which we have again 

 assembled. 



In these remarks I have carefully avoided any allusion to the 

 origin of species, because Geology suggests no theory of natural 

 causes, and Palaeontology affords no support to the hypothesis 

 which seeks by a system of evolution to derive all the varied 

 forms of organic life from pre-existing organisms of a lower type. 

 As far as I have been able to read the records of the rocks, I 

 confess I have failed to discover any lineal series among the vast 

 assemblage of extinct species which might form a basis and lend 

 reliable biological support to such a theory. Instead of a grada- 

 tion upwards in certain groups and classes of fossil animals, we 

 find, on the contrary, that their first representatives are not the 

 lowest, but often highly organised types of the class to which 

 they belong. This is well illustrated in the Corals, Crinoids, 

 AsteriadK, Mollusca, and Crustacea of the Silurian age, and 

 which make up the beginnings of life in the Palaeozoic period. 

 The fishes of the Old Red Sandstone we have already seen 

 occupy a respectable position among the Pisces ; and the Reptiles 

 of the Trias are not the lowest forms of their class, but highly 

 organised Dinosauria. Ichthyosaurus, Plesiosaurus, Pterodactylus, 

 Teleosaurus, and Megalosaurus stand out in bold relief from the 

 Mesozoic strata as remarkable types of animal life that were 

 specially organised and marvellously adapted to fulfil important 

 conditions of existence in the Reptilian age ; they afford, I 

 submit, conclusive evidence of special work of the Great De- 

 signing Mind which pervades all creation, organic and inorganic. 

 In a word. Palaeontology brings us face to face with the Creator, 

 and shows us plainly how in all that marvellous past there always 

 has existed the most complete and perfect relation between 

 external nature and the stmcture and duration of the organic 

 forms which gave life and activity to each succeeding age. 



Palaeontology likewise discloses to our feeble understanding 

 some of those methods by which the Infinite works through 

 natural forces to accomplish and maintain His creative design, 

 and thereby teaches us that there has been a glorious scheme, 

 and a gradual accomplishment of purpose through unmeasured 

 periofls of time ; but Palaeontology affords no solution of the 

 problem of creation, whether of kinds, of matter, or of sjiecies 

 of life, beyond this, that although countless ages have rolled 

 away since the denizens of the Silurian beach lived and moved 

 and had their being, the same biological laws that governed 

 their life, assigned them their position in the world's story, and 

 limited their duration in time and space, are identical with those 

 which are expressed in the morphology and distribution of the 

 countless organisms which live on the earth's surface at the 

 present ttme ; and this fact realises in a material form the tmth 

 and force of those assuring words, that the Great Author of all 

 things, in these His works, is the same yesterday, to-day, and 

 for ever. 



