I I 36 PARRnVSIA 



Var. chariensis (Germain). 



"This shell differs from the type by its much shorter form, 

 being- elliptic-oval ; by its dorsal margin slightly ascending 

 and a little subconvex ; by its ventral margin, not straight, but 

 very notably and regularly convex ; by the higher posterior 

 region by reason of the greater divergence of the dorsal and 

 ventral margins, so that the greatest height is not uniform with 

 that through the beaks, as in the type, but is in the posterior 

 region ; by the two quite pronounced dorsal angles ; etc." 

 (Germain). 



Type locality, La Mamoun, Senoussi country. 

 Unio nmtelcpformis var. cliariensis Gurmain^ I'Afrique Cent. 



Fr., 1907, p. 541. 



"In this little shell, the beaks are much less prominent, the 

 ligament is less strong, and very short ; the epidermis of a pale 

 yellowish-red, with fine, close and regular lines of growth; 

 the nacre is of a very iridescent, brilliant rose-salmon color." 



Parreysia hypsiprimnus (von Martens). 



Shell trapezoid or subrhomboid, solid, inflated, somewhat in- 

 equilateral ; beaks moderately full and high ; posterior ridge 

 full, rounded, ending in a blunt point near the base ; anterior 

 end somewhat narrowed, rounded ; base nearly straight ; dorsal 

 outline slightly sinuous, arched from the beaks to the end 

 of the ligament ; posterior end obliquely truncate ; surface cov- 

 ered with peculiar, strong, wavy, concentric sculpture ; epi- 

 dermis dirty brown ; teeth rather strong ; laterals curved ; nacre 

 whitish. 



Length 33, height 23, diam. 16.5 mm. 



Lake Nyassa. 

 Unio liypsiprimnns von Martins, Besch. Deuts. Ost-Af., 



1897, P- 230, pi. VII, fig. I. — Germain, Bull. Mus. Hist. Nat., 



1906, p. 302, figs. 8-16. 

 Parreysia hypsipmiimis Simpson, Syn., 1900, p. 849. 



A peculiar species, of which the type is very badly eroded. 

 The sculpture consists of wavy or somewhat ragged, concen- 

 tric ridges, differing from that of any allied form that I am 

 acquainted with. 



