260 



MR. T. ROBERTS ON THE UPPER JURASSIC ROCKS 



The fauna connects these beds also with our Coral Rag, and they 

 must be regarded as belonging to that horizon. 



The ' Calcaires a Nerinees,' which are the same as the Diceras-be&s 

 of Oppel, are, by him, stated to be probably represented in England 

 by part of the Kimeridge Clay, and probably also by the Upper 

 Calcareous Grit (op. cit. tab. p. 805); in his tab. no. 64, however, 

 be places them on the horizon of the Upper Calcareous Grit (?). 



The list of fossils from these Merincea-loeds contains 192 species 

 (Greppin, op. cit. p. 88), 28 of which are British ; 2 only of these 

 are restricted to our Kimeridge Clay, viz. Turbo Julii and Bostellaria 

 mosensis, 4 are Lower-Oolite forms, whilst the remaining 22 species 

 are Corallian. Out of these 22 species — 



13 occur in the Coral Rag. 



2 occur in the Coralline Oolite. 



3 occur in the Coral Rag and Coralline Oolite. 



4 range from Oxford Clay and Lower Calcareous Grit 

 — to the Coral Rag. 



22 



The Coral Rag and Coralline Oolite species include — 



Nerinaea Eoemeri, Goldf. 



clymene, D'Orb. 



Turbo princeps, Goldf. 

 Pecten qiialicosta, Et. 

 Terebratula insignis, Sckiib. 

 Cidaris florigemma, Phil. 



Hemicidaris intermedia, Flem. 

 Grlypticus hieroglyphicus, Goldf 

 Pseudodiadema radiata, Phill. 

 Thecosmilia annularis, Flem. 

 Thamnastrea concinna, Goldf. 

 Stylina tubulifera, Phil. 



All of them belong to our Coral-Rag fauna. It has already been 

 stated that these iVmncpa-limestones are, in some localities in 

 the Jura, crowded with corals, and here they were undoubtedly the 

 sites of old coral-reefs. Many of the corals in these reefs are similar 

 to those which occur in rocks having much the same character in 

 England, and which are, for the most part, of Coral-Rag age, although 

 not exclusively so, since some are known from the Upper Calcareous 

 Grit, as, for example, the reef at Ringstead Bay (Blake and Hudle- 

 ston, Q. J. G. S. vol. xxxiii. p. 272). The most striking difference 

 between the coral fauna of the British Corallian reefs and those of 

 the Jura is the larger number of species in the latter. Prof. Koby 

 informed us that about 200 species had been described from these 

 coral-bearing beds at Caquerelle. This richer coral fauna in the 

 Jura may be due to a more suitable climate for coral-growth having 

 existed there than in England. Neumayr has shown that tropical 

 conditions prevailed in the region of the Jura during Jurassic times, 

 whilst in England the climate was more temperate. The mere presence 

 of coral-reefs in the ' Calcaire a JNerinees' of the Jura, and in the 

 Coral Rag of England, does not by any means prove that they are of 

 the same age ; when, however, the number of fossils, corals as well 

 as higher forms of life, which are common to both are taken into 

 consideration, it seems highly probable that they belong to approx- 

 imately the same period. The ' Calcaire a Nerinees ' contains no 

 Upper-Calcareous-Grit and only two Kimeridge-Clay fossils, so there 



