DIPLOIOON 1309 



ly. concentrically grooved ; epidermis delicately lamellated and 

 serrate ; pseudocardinals small ; laterals elongated ; anterior 

 muscle impressions small, well marked ; posterior scars super- 

 ficial ; nacre bluish-white. 



Animal unknown. 



Type, IJnio stagnonini Dautzenberg. 



DiPLODON STAGNORUM ( Dautzenbcrg) . 



Shell irregularly obovate, compressed or convex, thin, in- 

 equilateral ; beaks but slightly full or elevated, apparently 

 without sculpture ; anterior end cut away above and below and 

 produced forward into a rounded point ; posterior end wid- 

 ened, irregularly rounded ; dorsal and basal outlines curved ; 

 posterior ridge widely rounded ; surface concentrically sculp- 

 tured ; epidermis brownish, finely lamellate ; pseudocardinals 

 small, apparently not well developed ; laterals elongated, del- 

 icate, curved ; nacre bluish-white, brilliant. 



Length 48, height- 33, diam. 17.5 mm. 



Congo River, Africa. 

 Unio stagnonim Dautzrnberg, Bull. Acad. Belg., XX, 1890, 



p. 372, pi. I, figs. 7, 10. 

 Diplodon stagnornm »Simpson, Syn., 1900, p. 894. 



A peculiarly shaped species, having the anterior end pro- 

 duced forward on the median line to a blunt point, and the pos- 

 terior end wide and irregularly rounded. Dautzenberg states 

 that the beaks are smooth. I am inclined, from his careful 

 description and figures, to place the species in the genus Dip- 

 lodon. 



SPKCIKS IXCERT.^v SKDIS. 



Diplodon panco von Ihering. 



"Shell of moderate size, solid, more or less oval or oblong 

 in outline and somewhat inflated. The anterior end is smaller 

 than the posterior and quite evenly rounded, whereas the pos- 

 terior is obliquely truncate. Dorsal margin slightly convex, 

 postero-dorsal angle obtusely rounded, posterior margin 

 oblique, nearly straight. Ventral margin almost straight, 

 slightlv convex in the centre. Beaks not prominent, much 



