1927] Pilsbry-Bequaert, The Aquatic Mollusks of the Belgian Congo 217 
The shell is minutely perforate, Ampullaria-shaped, pale translucent gray, glossy 
and smooth, the growth lines very faint. The whorls are strongly convex, the last 
somewhat flattened below the suture, everywhere well rounded. The aperture is 
slightly oblique, very broadly oval, the peristome dark-edged, in a plane. The oper- 
culum lodges at its edge, and is slightly concave in the middle. It is composed of 
about 2)4 spiral whorls. The nucleus central; surrounding this is a band of concentric 
increment about one-fourth the width of the operculum. 
Length, 2.2 mm.; diameter, 2.3 mm.; aperture, 1.4 mm.; 3 whorls. 
One of the most globose species. It has some resemblance in contour 
to the figure of the undescribed B. nyassanus (Bourguignat), from Lake 
Nyasa, but that is far larger. It has not the rapidly enlarging last whorl 
and expansion at the aperture of B. alberti, but it is like that species in 
having the operculum mainly spiral. Four small specimens, apparently 
of the same species, were found among Lobogenes michaels near the source 
of the Kimilolo River, here a brook. 
Fig. 17. Bulimus kisalensis Pilsbry and Bequaert, shell and operculum of type. 
Kikondja. 
Other Species of Gabbia Recorded from the Belgian Congo 
Bulimus (Gabbia) wallert (E. A. Smith) 
Bythinia wallert E. A. Surru, 1888, Proc. Zool. Soc. London, p. 54, fig. 3 (on p. 
= Bithynia (Gabbia) walleri E. A. Smith. E. v. Marrens, 1897, ‘Deutsch Ost 
Afr., IV, Beschalte Weichth.,’ p. 191. 
Lake Albert: (type locality, without more definite indication; Emin Pasha 
Coll.). 
Subgenus Paranerira Annandale 
Hydrobioides subgenus Paranerita ANNANDALE, 1920, Rec. Indian Mus., XIX, 
p. 45. Monotype: Hydrobioides physcus Annandale. 
The last whorl expands and is thickened outwardly at the aperture. 
The spiral part of the operculum occupies fully half of its width. | 
The following African forms agree technically with Annandale’s 
Indian group, but we feel somewhat doubtful about the actual relation- 
ship. 
Bulimus alberti (E. A. Smith). See p. 218. 
Bulimus humerosus (E. v. Martens). See p. 219. 
