90 



PALAEONTOLOGY. 





climate, might be expected to shew the greatest variety, 

 and the most complete and rapid alterations of organic life. 

 In the London clay are found many species of Clavella, 

 Typhis, Mitra, Pseudoliva, Oliva, and Ancillaria ; and some 

 extinct forms (Leiostoma and Strepsidura) related to Fusus. 



Fig. 28. 



Tertiary Univalves. 



Nautilus (Aturia) zic-zac, Sby. ; Eocene, Britain. 

 Nautilus zic-zac, front view of a septum. 

 Conorbis dormitor, Sol. ; Eocene, Britain. 

 Borsonia lineata, T. Edw. ; M. Eocene, Hants. 

 Volutilitbes luctator, Sol,; Eocene, Britain. 

 Natica (Deshayesia) cochlearia, Brongn. ; Eocene, N. Italy. 

 Turritella (Proto) catbedralis, Brongn. ; Miocene, Bordeaux. 

 Nerita (Velates) perversa, Gm. ; Eocene, France. 

 Helix (Lychnus) Matberoni, Keq. ; Eocene, S. France. 

 Ferussina tricarinata, M. Br.; Miocene, Hockbeim. 

 Volvaria bulloides, Lam. ; Eocene, Grignon. 

 Vaginella depressa, Bast. ; Miocene, Bordeaux. 



The middle tertiary, wanting in England, but largely deve- 

 loped in Central and Southern Europe, also contains many 

 genera belonging now to warmer latitudes, and many species 

 still living in the south. In the newer tertiaries of Europe 

 these southern forms disappear, and are gradually replaced by 

 others of an opposite character (Tvophon, Neptunia, and Tricho- 

 tropis), now inhabiting the Arctic and boreal coasts. The entire 



