Dr. C. Struchnann — The Jura of Hanover and England. 553 



In the Kimmeridge generally 22 species. 



Only in lower beds 3 ,, 



In the Lower Kimmeridge generally 14 ,, 



In the Middle Kimmeridge generally 19 ,, 



Exclusively in the Kimmeridge 17 ,, 



Of the last-mentioned, Ostrea Monsbeliardensis, Neritopsis delphimda 

 and Hybodus acutus, have hitherto been found only in the Lower 

 Kimmeridge ; and Pinna granidata, Mactromija rugosa, Corbida 

 DesJiayesea, and Alaria nodifera, onl^^ in the Middle Kimmeridge or 

 higher. On the other hand, Exogyra virgidn. Area riistica, Nucula 

 Menlcei, Astarte supracorallina, Gardiiim eduUforme, Isocardia striata, 

 Ceromya excentrica, Pleuromya tellina, Tornatella secalina, and Lepi- 

 dotus giganteus are distributed through different zones of the North- 

 German Kimmeridge. Lastly we have to mention Liicina suhstriata, 

 Ostrea solitaria, and Asteracanthus ornatissimns as species which 

 occur in the Middle Kimmeridge, near Hanover, but at the same 

 time extend down into the Coralline Oolite. 



Between the English Lower Kimmeridge Clay and the Hanoverian 

 Kimmeridge a tolerably close palceontological relationship therefore 

 exists, although the phase of development is quite different. For 

 while the Lower Kimmeridge Clay presents a very rich and varied 

 Cephalopodal fauna, the North- German Kimmeridge is in this 

 respect remarkably poor. Nevertheless both the conditions of 

 stratification and the fauna indicate that the parallel is to be sought 

 in the North-German Pteroceras-heds (i.e. in the Middle Kimmeridge 

 beds). It is true that the so-called characteristic fossils furnish even 

 in this case no satisfactory standpoint ; Ostrea deltoidea, so abundant 

 in the Lower Kimmeridge, occurs near Hanover only in lower 

 deposits; and on the other hand, Pteroceras oceani has hitherto 

 been found in England only in a higher zone. But it appears 

 to me to be not unimportant that both in the English Lower 

 Kimmeridge and in the North-German Pteroceras-heds the remains 

 of higher animals, namely, Saurians, Chelonians, and Fishes, are 

 deposited in great variety, although as yet we have succeeded in 

 determining the species only in a few instances. Notwithstanding 

 the divergence of the phase of development in many respects, the 

 fauna of the North-German Middle Kimmeridge beds bears on the 

 whole the character of the English Lower Kimmeridge Clay, so that 

 the palseontological conditions are not in opposition to a parallelism. 

 At any rate, the development of the South- and North- German 

 Kimmeridge exhibits considerably greater differences. If, therefore, 

 the Lower Kimmeridge Clay must be regarded as the equivalent 

 of the Pteroceras-heds, then, in accordance with my previous demon- 

 strations (in my monographic memoir upon the Upper Jura of the 

 neighbourhood of Hanover), the Nattheim Coralline Limestone of 

 Swabia (e of Quenstedt), the Wettinger beds of Eastern Switzerland, 

 as also the Pterocerien of Western Switzerland and the French 

 Upper Jura, are to be considered contemporaneous deposits. 



7. I have already indicated elsewhere' that the comparison of the 



* Der obere Jura d. Umg. v. Hannover, p. 166. 



