London Clay. 247 



and many species of Rays (Myliobatis). Of the Cepha- 

 lopoda, Nautilus (N. Sowerbyi, &c.) is common, to- 

 gether with Cephalopode, Belemnosis plicata, Belosepia 

 sepioidea, and Beloptera Levesquei. Ammonites and 

 Belemnites, genera common in the Cretaceous strata 

 have disappeared. Gasteropoda occur in vast profusion, 

 the most prominent genera being Fusus (F. regularis, 

 F. Iceviusculus, &c.), Murex (M. crista,tus, M. coro- 

 natus, &c.), Pleurotoma (P. Helix, P. Keelii, &c.), 

 Voluta (V. nodosa, &c.), Pyrula (P. Smithii, &c.) 

 Cyprcea (C. oviformis), and Eostellaria (E. ampla, 

 &c.). Lamellibranchiata, though common, are less 

 numerous, including among others the genera Pinna 

 (affinis, &c.), Pholadomya (Dixoni, &c.), Area, Avi- 

 cula, Pecten, Cardium, Cyprina, Nucula, &c. 

 The Brachiopoda are only represented by Lingula 

 tenuis and Terebratulina, striatula, and there are a 

 few Polyzoa. Crustacea are exceedingly numerous, 

 especially crabs (Brachyura and Anomura), including 

 the genera Xanthopsis, Hoploparia, &c. ; and of 

 Entomostraca, Cy there is common of many species. 

 Among the Echinodermata we have Hemiaster Bower- 

 bankii, &c. ; Goniaster, Cidai is, Astropecten Colei, &c. ; 

 Ophiura Wetherellii, and Pentacrinus, and there are 

 also a few Corals. Many of the fossils of the London 

 Clay are found in other strata both above and below that 

 formation, but a larger proportion is common to the 

 overlying than to the lower formations. 



Looked at in a comprehensive way, an accurate 

 observer cannot fail to be struck with the fact that the 

 assemblage of fossils found in the London Clay point in 

 this direction, viz., that the whole of these strata were 

 deposited in the estuary of a great continental river 

 comparable to the Amazons and the Ganges. The Palm- 



