1927] Pilsbry-Bequaert, The Aquatic Mollusks of the Belgian Congo  ~—- 185 
penis is substantially as described for Pila congoensis. These parts are 
drawn in Fig. 16), from an individual of average size. 
Lanistes (Leroya) grauert has the lung orifice as described above but 
smaller—a slit 4 mm. long, at the left border of the lung, immediately 
behind the prominent osphradium, which is about 2 mm. from the edge 
of the mantle. 
Lanistes nsendweensis also has the lung orifice situated as in L. p. 
langt, at the left border of the lung, about 7 mm. long in a shell of 24 mm. 
diameter. The penis (seen turned into the mantle cavity in Fig. 16a) 
is slender and grooved, as described for Pila congoensis and L. p. langi, 
with a fleshy sheath perforated at the end, but the folded edges are con- 
crescent. It is 4 mm. long (as preserved in alcohol) in a shell of 21 mm. 
diameter. : 
Fig. 16. a, Lanistes nsendweensis Dupuis and Putzeys, penis turned into the 
mantle cavity. 6, Lanistes procerus langi Pilsbry and Bequaert, head and front of — 
mantle. 
ll, rl, left and right epipodial lobes; p, penis. 
The radular teeth of Lanistes do not appear to differ materially 
from those of Pala, though in the three species we have examined the 
central teeth differ in outline, having narrower upper margin and more 
sloping side margins than in Pla congoensis. L. graueri is peculiar by 
the broad body of the inner marginal tooth. The teeth of both genera 
are drawn in Fig. 18, on p. 168. 
Lanistes (Lanistes) nsendweensis (Fig. 13e) has the upper margin 
of the central tooth shorter, the lateral margins sloping less steeply. 
The body of the lateral tooth is narrower; even when the tooth is lying 
free, the cusps foreshortened, it is not so wide as in Pla. Formula of 
cusps as in Pila, except that the central has seven denticles instead of 
five. Width of the central tooth, 0.377 mm. | 
Lanistes (Meladomus) procerus langi (Fig. 18c) differs from L. 
nsendweensis by having the side teeth decidedly longer. Width of the 
central tooth, 0.525 mm. | 
