1028 NODULARIA 
NoDULARIA LACOINI Germain. 
“Shell elongate-oval, quite inflated, solid, opaque; dorsal 
margin almost straight; anterior margin rounded, slightly an- 
gulated above; ventral margin regularly convex; posterior re- 
gion elongated, one and one-half to two times as long as the 
anterior, with the dorsal edge quite sharp in young shells, 
becoming obtuse in the adults; beaks prominent, often eroded, 
and, in such cases, showing a white nacre, upon which the 
apical sculpture is clearly defined; two cardinal teeth in the 
right valve, relatively quite elongate, the lower higher than 
the upper, separated by a deep groove; in the left valve a sin- 
gle, high, stout, slightly compressed and finely sulcate car- 
dinal; laterals two in the left valve, thin, compressed, parallel 
and separated by a deep groove; in the right valve one, very 
long, elevated and quite sharp; anterior muscular impressions 
round and quite deep; posterior superficial. Epidermis pale 
chestnut, sometimes tinged with yellow; lines of growth very 
fine, but irregular; umbonal region tuberculate or with zig- 
zag ridges; nacre iridescent, bluish or roseate. 
Length 30-36. height 19-22, diam. 14-16 mm.’’ (Germain). 
Type locality, Kanassarom, on the north-east side of Lake 
Tchad. Also, Faguibine, Upper Senegal. 
Unio (Nedularia) lacoimi GERMAIN, Bull. Mus. Hist. Nat., 
1905, p. 489; Mem. Soc. Zool. Fr., XIX, 1906, p. 237, pl. 
Iv, figs. 11, 12; PAfrique Cent. Fran., 1907, p. 545- 
“This species is excessively polymorphic both in form and 
sculpture. Thus the following mutations can be distinguished, 
which define themselves: 
Var. ex-forma: elongata Germain. 
curta Germain. 
compressa Germain. 
The sculpture of the shell consists, fundamentally, of quite 
fine striae, which, in some examples, become strong, quite 
heavy and very irregular. To this is added, sometimes, in the 
umbonal region either tubercles or chevrons or occasionally 
both. 
