MANUAL OF THE MOLLUSCA. 



'■^Animal allied to Natica; foot small, compact without any 

 posterior lobe ; the front lobe deeply sinuated ; eyes subcuta- 

 neous, situated at the internal base of the lobe ; operculum 

 terminal, few-whorled, horny, thin. 



'^ Shell ovate, imperforate, spire small, produced; mouth 

 reversed, pear-shaped, about half the length of the shell." 

 (MoUer.) 



Fossil, species. Cretaceous. Germany, Britain. 



Deshayesia, Eaulin, 1844 (see p. 236). 



Dedicated to M. Deshayes, author of " Description des Ani- 

 maux sans Yertebres dans le bassin de Paris," &c. 



Synonym, Naticella, Grateloup (non Miinster). 



Type, D. Parisiensis, Eaulin. 



Shell subglobose, thick, umbilicated ; spire short ; aperture 

 entire, semicircular, oblique ; columella oblique; callosity den- 

 ticulated ; umbilicus covered by the callosity ; right lip acute, 

 sraooth internally. 



This genus presents a very remarkable combination of the 

 characters of Natica and Nerita, and appears to establish a pas- 

 sage between these two genera, types of distinct families. 



Distribution, 2 species. Oligocene and Miocene. Paris and 

 Bordeaux Basins 



Ptychostoma, Laube. 



Fossil, 3 species. St. Cassian. 



[Family CANCELLAnn)^.] 



The genera are — 



Cajstcellama {Admete, p. 216), Trichotropis (p. 216), 

 ? Cerithiopsis (p. 242), ? Separatista, and 



PTJRPURrN-A,* D'Orbigny, 1850 (p. 222). 

 Type, Purpurina Bellona, D'Orbigny, Pig. 12. 



* This genus has been the subject of careful research and revision by Messrs. 

 Eugene Deslongchamps and Piette ; and I think it advisable to replace the characters 

 of this group, given in p. 222 of the Manual, by those emended by the authors above 

 jBentioned, 

 IS 



