J. F. BLAKE ON THE KIMMERIDGE CLAY OE ENGLAND. 213 



Plesiosaurus, sp. 

 Gyrodus ornatissimus, Bla. 

 Pycnodus quincuncialis, Bla. 

 Ammonites biplex, Sow. 



decipiens, Sow. 



Berryeri, Les. 



Ceritbium forticostatum, Bla. 

 Fusus tertius, Bla. 

 Dentalium Quenstedti, Bla. 

 Corbula Deshayesia, Buv. 

 Area rbomboidalis, Cont. 

 Astarte supracoralHna, U Orb. 



Micbaudiana, D' Orb. 



ovata, Sow. 



Nucula Menkii, Bom. 



Cardium striatulum, Sow. 

 Trigonia Juddiana, Lye. 

 Pecten Grenieri, Cont. 

 Tbracia depressa, Sow. 

 Pholadomya obliqua ?, Ag. 

 Pleuromya tellina, Ag. 

 Lima virgulina, Cont. 

 Avicula dorsetensis, Bla. 

 Exogyra virgula, Sow. 

 Ostrea deltoidea, Sow. 

 Inoeeramus expansus, Bla. 

 Bbyncbonella pinguis, Bom. 

 Lingula oyalis, Sow. 

 Serpula runcinata, Sow. 



To these we might add some of the fossils recorded by Dr. Waagen, 

 especially those of his middle region, viz. Bostellaria nodifera and 

 mosensis, Cardium pseudoaccinus, Lucina substriata, and Opis supra- 

 jurensis. They appear to have been gathered at the base of his 

 middle region, and must have been associated with many of those 

 above. 



KlMMERIDGE PASSAGE-BEDS. 



The clays just described at "Weymouth pass downwards into a 

 series of more sandy and stratified beds, with a peculiar suite of 

 fossils, which may be best described as passage-beds, and of which 

 this is the typical locality. They are the equivalent to part of 

 Dollfus's " Calcaires a Trigonies " of the Cap de la Heve, according 

 to Dr. Waagen, who includes part of them in the Upper Calcareous 

 Grit. They have always been called Kimmeridge Clay, or, by 

 Damon, the Kimmeridge grit ; and fossils found in them inland 

 have always been referred to that formation. Yet it must be 

 acknowledged that the change in the fossils as we enter these beds 

 is very striking, and accompanied by a lithological change. With 

 some fossils peculiar to them are associated other species, found 

 above and below in about equal numbers. I have found no indica- 

 tion of such beds where the Coral Rag is absent, as in Lincolnshire ; 

 but in the presence of that formation they are everywhere developed. 

 This would serve to attach them rather to it than to the Kimmeridge 

 Clay. The change, no doubt, both in the character of the deposit 

 and in the accompanying life was gradual, and certain species were 

 specially adapted for such intermediate circumstances ; and this gives 

 us the history of the deposits. Instead, therefore, of drawing hard 

 and fast lines, it would be well to recognize such passage-beds ; and 

 calling them after the overlying series, particularly for mapping- 

 purposes, they will receive the above proposed title. 



The following is the section as exhibited on the shore beyond 

 Sandsfoot Castle. The thickness is only estimated by the extent of 

 ground covered between the surface outcrops, and is probably slightly 

 above the truth. 



q2 



