OP THE SWISS JXfRA AND ENGLAND. 



26i 



is little or no evidence to show that they represent any part of our 

 Upper Calcareous Grit or Kimeridge Clay. It is possible, and, 

 indeed, appears to be highly probable, that the period during which 

 coral-reefs flourished in the Jura may not have terminated at the 

 same time as in England ; if such was the case, then the coral- 

 reef fauna would have survived as long as the physical condi- 

 tions were favourable, with little or no change. That such was the 

 case in England is shown by the fossils of the BAngstead-Bay reef, 

 which stratigraphically comes immediately below the Kimeridge 

 Clay, yet its fauna is precisely like that of the Coral Eag (Blake and 

 Hudleston, Q. J. G. S. vol. xxxiii. p. 272). If the two Kimeridge- 

 Clay species which are recorded from the 'Calcaire a Nerinees' be 

 taken as an indication of the commencement of the introduction of 

 the Kimeridgian fauna into the Jura, we may then regard the ' Cal- 

 caire a Nerinees ' as being represented in England by a portion of 

 our Coral Rag and the whole of the Upper Calcareous Grit, and what 

 other evidence there is would not be opposed to such a view. 



The three stages which overlie the Corallian of the Jura, viz. the 

 Astartian, Pterocerian, and Yirgulian, are closely united together, 

 both in their lithological character and in their fauna, and by some 

 geologists are included in one group, which they term the Kimer- 

 idgian. The Astartian is regarded by Oppel and Waagen as repre- 

 senting the lower part of the Kimeridge Clay ; but Renevier places 

 it on the horizon of the upper part of our Corallian. Blake (Q,. J. 

 G. S. vol. xxxvii. p. 580) correlates the Astartian of France, 

 which, from its fossils, appears to be the same as that of the Jura, 

 with the Kimeridge Passage-beds, including the Abbotsbury and 

 Westbury ironstone, and with the basal portion of the Lower Kimer- 

 idge Clay. 



Greppin {op. cit. p. 101) gives 210 species from the Astartian of 

 the Bernois district, 40 of which occur in England at the following 



horizons respectively : — 



Lower Oolites 2 



Coralline Oolite and Coral Rag 15 



Kimeridge Passage-beds (including the Abbots- 

 bury Ironstone) 7 



Kimeridge Passage-beds and Lower Kimeridge 



Clay 7 



Upper Kimeridge 1 



Corallian and Lower Kimeridge . . 8 



40 



The Kimeridge Clay of England has been fully described by Blake 

 (Q. J. G. S. vol. xxxi. p. 196), and the following fossils, amongst 

 others, he regards as being peculiar to the Kimeridge Passage-beds 

 (including the Abbotsbury Ironstone) : — 



Natica eudora, D'Orb. Area sublata, If Orb. 



Pleuromya Voltzii, Ag. Lucina plebeia, Contj. 



■ donacina, Ag. Rhynchonella inconstans, Sow. 



Goidomya parvula, Ag. 



