NODUTLARIA 981 
Ne@DULARIA TERETIUSCULA (Philippi). 
Shell elongated, subinflated or inflated, rather solid, inequi- 
lateral, with the greatest diameter along and just in front of 
the angled posterior ridge; anterior end rounded; base line 
nearly straight, full towards the posterior end and obliquely 
truncated behind the inflation; posterior point somewhat drawn 
out, about midway up from the base; dorsal outline slightly 
curved; post-dorsal slope somewhat obliquely truncated ; beaks 
moderately elevated, with slightly converging, more or less 
zigzag-radial sculpture; surface with irregular growth lines 
and sometimes with faint, seminodulous, subplicate sculpture 
anteriorly and posteriorly ; epidermis gray-green to blue-green, 
generally slightly rayed, dull; left valve with two compressed, 
elevated pseudocardinals and two slender laterals; right valve 
with one pseudocardinal, often divided and one lateral; ante- 
rior scars impressed; nacre bluish, slightly iridescent. 
Length 50, height 20, diam. 16 mm. 
Upper Nile drainage. 
Unio teretiusculus Puitippi, Conch., III, 1847, p. 45, pl. m1. 
fig. 3—?Kuster, Conch. Cab., 1856, p. 133, pl. xxxv, fig. 5. 
—Sowerpy, Conch. Icon., XVI, 1868, pl. Lxxv, fig. 389.— 
jieKecy Faun, gO. Af., 1874,.p. 276, pl. X1, figs. 1,-2. 
Nodularia teretiuscula Simpson, Syn., 1900, p. 812. 
Margarita (Umio) cailliaudi Lea, Syn., 1838, p. 24. 
Margaron (Unio) cailliaudi Lea, Syn., 1852, p. 36; 1870, p. 58. 
Although this is an African species, it appears to be very 
closely related to N. c@rulea, which is confined to southeast 
Asia. It is a little more elongated than that species, is more 
solid, is usually somewhat rayed, while cerulea is rayless or 
almost so, and it has duller nacre. 
Var. lithophaga “Ziegler” Pallary. 
‘Differs from the type figured by Philippi by its smaller 
size, its beaks nearer the posterior margin and more elongated 
anterior end.” (Pallary). 
Type locality, the White Nile. 
Unio lithophagus ZiecLeR, manuscript, probably. 
