1927] Pilsbry-Bequaert, The Aquatic Mollusks of the Belgian Congo 189 
those from between Kikondja and Ankoro we refer to L. nsendweensis (Dupuis and 
Putzeys), while those from the Little Lubembe River are described in this paper as a 
new subspecies of nsend7veensis. 
Kidada, in the Lukungu River (H. Schouteden Coll.). 
This is a much more depressed shell than L. lybicus (Morelet), char- 
acterized by the flat, horizontal zone below the suture, rectangularly 
bounded by a shoulder angle, which in old specimens becomes rounded 
on the latter part of the last whorl. This shoulder angle causes the spire 
to rise by abrupt stages. The first three-quarters of a whorl are strongly 
convex, the keel then beginning. The surface shows fine, irregular 
growth-strize and very weak, minute and close spirals. In unrubbed, 
young examples, the fine axial striz bear delicate cuticular threads, 
which also unite at intervals into spirals. In one specimen there are 
several inconspicuous and irregularly developed spiral ridges, like 
those produced by malleation, on the last whorl. A blunt keel bounds - 
the rather large, well-like umbilicus. 
Length, 21.5 mm.; diameter, 23 mm.; 4)4 whorls, the apex perfect. 
These specimens are not so large as O. Boettger’s type, but they 
- agree with that in the contour of the spire. 
In a lot of small, but apparently adult, shells from Boma (Lang and 
Chapin Coll.), Pl. X VIII, figs. 13-15, the spire is more elevated than in 
typical congicus, not so high as in the var. schepmani. The carina above 
is decidedly nearer the suture, and weakens on the last whorl. The 
narrow umbilicus has a rather strong bounding cord, and the dull reddish 
bands cover most of the surface. These specimens do not appear refer- 
able to either of the forms assembled under L. congicus, but in the 
present condition of the subject we hesitate to segregate them by another 
name. 
Length, 15.0 mm.; diameter, 17.0 mm. 
he lh « 16.0 ; 4% whorls. 
Lanistes congicus fraternus, new subspecies 
»« Plate XVIII, Figure 16 
Congo River, 2 to 3 kilometers below Kinshasa, on- the Belgian 
side (type locality); also bank of the Congo at Dolo (near Kinshasa). 
On floating plants (Maurice Bequaert Coll.). 
The shell resembles L. congicus in being depressed, with a well-lrke umbilicus: 
The penult whorl is strongly angular above (earlier whorls eroded). The last whorl 
is flattened below the suture, but not in the least angular; it is bluntly angular around 
the umbilicus. It is glossy, with sculpture of growth-lines only. Color ecru-olive 
with blackish-brown bands. 
Length, 16.0 mm.; diameter, 19.0 mm.; aperture, 12.7X9.5 mm. 
