NODULARIA 1037 
almost squarely subtruncate above, bluntly pointed below the 
median line; surface sculptured with V-shaped ridges and 
strong subradial folds on the dorsal slope, epidermis brown- 
ish-green with green rays, which are stronger on the posterior 
end; hinge teeth sublamellar, but strong. 
Dar-es-Ssalam, East Africa. 
Unio ambifarius VoN Martens, Besch. Deuts. Ost-Af., 1897, 
p. 225, pl. vit, fig. 20. 
Nodularia ambifaria SIMPSON, Syn., 1900, p. 823. 
The shell of this species is almost regularly long quadrate, 
the dorsal and ventral outlines being parallel and the poste- 
rior end nearly squarely subtruncate above. It seems to be 
covered with delicate, zigzag sculpture, and has strong folds 
on the dorsal slope. It is strongly rayed for a member of this 
group. 
NopULARIA LECHAPTOISI (Ancey). 
Shell subelliptical, subinflated, slightly gaping in front, and 
solid; beaks apparently rather low, dorsal outline ‘curved ; 
anterior end rounded, very slightly cut away below; base line 
almost evenly curved; dorsal slope obliquely subtruncate ; pos- 
terior ridge rounded, ending below the median line in a round- 
ed point; upper part of the anterior and posterior ends sculp- 
tured with strong wrinkles; epidermis fuscous, blackish be- 
hind ; beaks roughened ; nacre pale salmon. 
Length 38, height 21.5, diam. 17 mm. 
Shire River, Lake Nyassa. 
Unie lechaptoisi ANcry, Bull. Soc. Zool. Fr., VII, 1894, p. 228, 
fig. 3. 
Nodularia lechaptoisi Simpson, Syn., 1900, p. 823. 
More nearly elliptical than N. borellu and having different 
nacre. 
NODULARIA LIEDERI (von Martens). 
Shell decidedly rhomboid, somewhat elongated, inequilat- 
eral, solid, subinflated: beaks moderately full and high with 
two divergent rows of tubercles; posterior ridge well develop- 
ed, subangular, ending in a blunt point below the median line ; 
