104 LIMN^ID^. 



PLESIOPHYSA, Fischer, 1883. Shell rather short. Central tooth 

 of the radnla 5-cuspiclate, the median cusp the longest. P. striata^ 

 d'Orb. W. Indies. 



PECHAUDiA, Bourg., 1882. Shell like Phj^sopsis, but dextral, 

 oval, transparent ; columellar axis with a white lamella, strongly 

 truncate at the base. P. Letourneuxi, Bourguignat. Algiers. 



Camptoceras, Benson, 1842. 



Distr — 3 sp. Swamps, in India. G. terebra, Benson (c, 35). 

 1 fossil species. Eocene ; Sheerness-on-Sea^ England, 



Shell sinistral, imperforate ; whorls tliree or four, separate, 

 flat, carinated above and below ; suture widely and profoundly 

 excavated ; aperture large, elongate-elliptical ; peristome thin, 

 continuous. 



Animal has two obtuse, filiform tentacles, with large eyes 

 placed between them ; mantle not larger than the lips of the 

 shell ; foot short. 



The description of the animal corresponds nearly with the 

 Limnophila, and the sinistral shell has caused authors to place 

 it in Physadge. 



Chilina, Gray, 1831. 



iSt/7i.— Dombeya, d'Orb, 183t. Potamophila, Swn., 1840. 



Distr. — 18 sp. South America. Fossil, 1 sp. Miocene; S, 

 Am. G. piielcha, d'Orb. (ciii, 22). It replaces the Limnsea of 

 North America ; lives in clear running streams. 



Shell dextral, oval, rather thin, usually ornamented with dark 

 spots or wavy bands ; columella thickened, with one or two 

 strong, prominent folds, peristome simple. Tentacles large, 

 flattened, with sessile eyes at their superior face ; pulmonary 

 pouch with a well-developed protecting lobe ; foot large, dilated 

 in front, attenuated behind ; genital orifices on the right side. 

 'No jaw ? Central tooth small, 5-cuspidate, laterals and marginals 

 multicuspidate, with a superior, external prolongation. 



PSEUDOCHiLiNA, Dall, 18t0, Shell thin, covered with a rough 

 fibrous epidermis ; spire elevated, acute. G. Limnaeformis, Dall. 

 Chili. 



PiTHARELLA, Edwards, 1860. 



Distr. — P. Bickmani^ Ed. " Woolwich and Reading Series," 

 Peckham and Dulwich, London. 



Shell partaking of the characters of Limnsea and Chilina, sub- 

 cjdindrical ; 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. 



