PAURrvsiA 1 135' 



like uniting it without more evidence. This may be a young 

 or not fully developed shell. It is less inflated, more strongly 

 and completely sculptured and duller colored than nyassaensis. 

 In the right valve there is a sort of triangular pit in the hinge 

 plate behind the pseudocardinals, which is not present in the 

 shells of 7iyassaeitsis I have seen. 



Parey.ssia MUTiiurvFORMis (Germain). 



"Shell small, very elongate recfilinear in shape ; rather solid, 

 slightly inflated ; dorsal and ventral margins nearlv parallel ; 

 dorsal margin straight : ventral margin nearly straight, slightly 

 subsinuous in the center and curved upwards towards the pos- 

 terior end ; anterior end rather short, well rounded ; posterior 

 part elongated horizontally, almost three times as long as the 

 anterior, keeping the same height as far as the postero-dorsal 

 ■angle, then narrowing, especially above, to a sharp posterior 

 end;- beaks rather anterior, (but very noticeably less than in 

 Ufiio nionceti Bourguignat ), somewhat inflated, compressed 

 laterally ; dorsal crest well marked ; in the right valve a double 

 cardinal and two, very long, rather low laterals; in the left, 

 valve, one, ver}' high, subquadrangular, distinctly crenulate 

 cardinal and one very long, rather low lateral ; anterior muscu- 

 lar impressions deep, posterior superficial. Epidermis yellow- 

 ish-chestnut or ochreous, sometimes very dark, somewhat worn 

 towards the beaks ; lines of growth quite delicate, regular, 

 stronger posteriorly ; nacre clear Prussian blue, quite iridescent. 



Length 24-26, height 9-10, diam. 5 mm." (Germain). 



Type locality. Lake Tchad. 

 IJnio WAitelccj ormis Germain, Mem. Soc. Zool. Fr., XIX, 



1906, p. 336; I'Afrique Cent. Fr., 1907, p. 540, pi. lith. figs. 



?^, 4- 



"This species can be compared only with Unio monceti 

 Bourguignat, but is distinguished by its smooth surface ; its 

 much more elongated fonn, though the posterior part is not. 

 as in typical monceti, three times as long as the anterior, as 

 the anterior end of nwuccli is remarkably short, very round, 

 with the beaks placed very anteriorly ; by the much less prom- 

 inent beaks and much more compressed form." 



