﻿PSEUDOSPATHA 203 



While none of these Oriental forms are very distinctly di- 

 morphic as to shell characters, it may be remarked that in 

 many species of the subgenus Proptera of Lampsilis the male 

 and female shells are hardly distinguishable. 



Germain, (1. c), however, refers the genus to the Mutelidce. 



PSEUDOSPATHA TANGANYICENSIS (Smith). 



Shell irregularly rhomboid, thin to subsolid, compressed, 

 gaping widely in front, on the anterior half of the base, and 

 shghtly behind, with a low, double posterior ridge ; a well-pro- 

 duced right angled anterior wing and a low, posterior one ; 

 narrowed in front and rounded on the anterior base, the out- 

 line full behind the center of the base, ending in a rounded 

 or somew^iat biangular point on the median line ; truncated on 

 the posterior slope ; beaks low, compressed, sculpture consisting 

 of concentric ridges developed into rows of rather sharp pus- 

 tules and showing the round, nepionic shell ; surface with irreg- 

 ular growth lines, copper-colored, sometimes rayed with green 

 on the posterior half of the shell ; left valve with a single un- 

 even, low, somewhat lamellar pseudocardinal and one or two, 

 more or less perfect, long laterals ; right valve with a single 

 pseudocardinal and one or two faint laterals ; muscle scars 

 shallow, with a couple of large scars placed at some distance 

 from the hinge line and well behind the beaks ; anterior scars 

 irregular, impressed ; posterior scars faint ; nacre purplish, soft 

 and iridescent. 



Length 95, height 44, diam. 17 mm. 



Lakes Tanganyika and Nyanza, Africa. 

 Spat ha tanganyiceiisis Smith, Proc. Zool. Soc. Lond., 1880, p. 



350, pi. XXXI, fig. 8. 

 Burtonia tanganyicensis P^tel, Conch. Sam., Ill, 1890, p. 187. 

 Pseudospatha tanganyicensis Simpson, Syn.. 1900, p. 577. — 



Germain, Moll. L. Tan., 1908, p. 684. — Arch. Zool. Exp. et 



Gen., (5), I, 1909, P- 47. figs. 42, 43. 

 Bnrtonia moineti Bourguignat, Un. and Ir. Tan., 1886, p. t,},; 



Icon. Mai. Tan., 1888, pi. xxv, fig. i. 



