GASTEROPODA. 



Synonym, Tebennophorus, Binney. 



Animal elongated, conyex, tapering behind, entirely coveretl 

 by a thin mantle ; resi^iratory orifice near the head ; jaw smooth. 

 No shell. 



Distrihition, 9 species. North America. 



Sub-genus : — Megliimatiiim, Hasselt. Syn., Indiana, Benson. 

 Body depressed, rounded at the end. 



Distribution, 4 species. Java, Chusan. 



Eamily IY. — LnrN^LD^.* 

 POMPHOLYX, Lea, 1856. 



Etymology, pompholux, lat. hulla. 



Type, P. eflPusa, Lea. Sacramento river, California. 



Shell gibbosely rounded, drawn back beneath, flattened 

 above, imperforate ; spire depressed ; aperture very large, 

 nearly round, effuse ; outer lip acute, inner lip thickened, 

 flattened. 



Animal with two long tentacles, bearing eyes, and a second 

 pair of eyes at the base on the inner side of the tentacles. 



Distribution, 2 species. Western America. 



PiTHAHELLA, Edwards, 1860. 



Type, P. Eickmani, Ed. "Woolwich and Eeading Series," 

 Peckham and Dulwich, London. 



Shell partaking of the characters of Limncea and Chilinia, 

 sub cylindrical ; aperture oval, rounded in front, narrowed 

 behind ; columella straight, or very obliquely twisted, arched 

 anteriorly ; outer lip simple, acute ; inner lip thickened. 



The species is associated with estuarine shells, remains of 

 mammals and terrestrial plants. 



Yaxenciekn^esia, Eosseau, 1842. 



Dedicated to the late Professor Valenciennes of Paris. 



Type, Y. annulatus, Eos. ; associated with fresh- water shells 

 in a tertiary deposit, near Kertch, Crimea. 



Shell resembles a gigantic Ancylus ; apex much incurved ; 

 surface concentrically marked. A longitudinal plication 

 extends from the apex to the right border, and corresponds 

 with an internal channel ; there is a second but less distinct 

 plication on the left side. 



Camptoistx, Benson, 1858. 

 Type, C. Theobaldi, Bens. Guzerat. 



• See p. 300. 



43 



