202 



when present is often found to contain a special flora; jaws 

 of Mammalia, belonging to the genera Amphitherium and 

 Phascolotherium, and the bones and teeth of Megalosaurus and 

 Pterodactyles, which were entombed in these slates, are Hkewise 

 special to them ; but the MoUusca and Echinidse of the same 

 beds are found in other members of the series. The Great 

 Oolite of Minchinhampton contains a very rich fauna, many 

 of the Molluscs extending through all the sub-divisions of 

 the group, whilst others, as Purpuroidea, Alaria, Pterocera, 

 Pachyrisma, &c., are special to it, and constitute exceptions 

 to the general facies of the fauna which has a much more 

 extended range through other formations. The Bradford Clay, 

 with Apiocrinus Parhinsoni, Terebratula digona, T. corarcta, 

 and T. cardium, is not always present ; and even when present 

 exhibits many phases of development, and appears to belong- 

 to one of the inlying argillaceous bands of the Forest 

 Marble. This formation forms an important division of the 

 group, and, although very fossiliferous, contains no sjjecies of 

 mollusc, urchin, or coral, which can be said to characterize 

 it, although the thinness of its beds and the amount of false 

 bedding and oblique lamination its sections disclose, show 

 that it was formed under very different conditions to the 

 regular strata of thick-bedded Limestones, which preceded and 

 followed this remarkably disturbed deposit. The Cornhrash^ 

 especially the development of this formation in Yorkshire, 

 contains some species that as yet appear to be special to it; 

 an examination of the list I have given of the fossils from the 

 Cornbrash of the Yorkshire coast, contained in the cabinet 

 of my old worthy fiiend John Leckenbt, Esq., F.G.S.,* by 

 whose assiduous collecting habits they have been accumulated, 

 and by whose liberality they were communicated for pubUca- 

 tion, will satisfy the student of this fact. This list is the more 

 important, as in making it out I had the advantage of my 

 friend's most accurate critical knowledge in guiding me in 

 determining the true character of all the species. 



* Quarterly Jmirnal of the Geological Society. Vol. xvi., p. 27 : 1860. 



