1927] Pilsbry-Bequaert, The Aquatic Mollusks of the Belgian Congo 263 
mens such as the type) obsolete, but under the lens there are fine, sharp, axial ripples, 
irregularly cut by a few spiral lines. The earlier whorls have strong spiral cords. The 
basal spiral cords are weak, variable. The color is citrous-drab, with a series of 
vertical oblong chestnut spots below the suture and smaller spots around the colu- 
mella. 
Length, 20.5 mm.; diameter, 8.0 mm.; 5 whorls remaining. Type. 
< 17.3 = 6.3 nearly 5 whorls remaining. 
The smallest specimens preserved, 9-10 mm. long, with 6-7 whorls, 
have already lost the tip (Pl. XXII, fig. 16). The early neanic whorls 
preserved are moderately convex, with three or four spiral cords. This 
stage continues to within about four whorls from the base. Then axial 
riblets set in— cut by impressed spiral lines, of which six may be counted 
in some individuals, fewer in others. On the penult whorl of adults 
these spirals have nearly or wholly disappeared except for one above 
the suture. 
Melanoides kisangani, new species 
Plate XXI, Figures 19-22 
Sandbanks of the Tshopo River, near Stanleyville, very abundant 
(H. Lang and J. Bequaert Coll.). | 
The shell is slender, rather thin, formed by flatsided whorls which are prominent 
below the suture. Surface very pale yellow, irregularly and sparsely strewn with 
chestnut spots; finely marked with lines of growth, not glossy. The earlier whorls are 
rather strongly convex, with three spiral cords, and weak, coarse, axial folds or waves. 
The last three whorls are flattened laterally, the upper spiral cord enlarges and be- 
comes coarsely tubercular, and the axial folds weaken. The last whorl has lost axial 
folds, and the spirals are obsolete or wanting between the subsutural series of tubercles 
(which are somewhat lengthened in a spiral direction) and the periphery; on the lower 
half there are about five spiral cords. The aperture is smal!, rather narrowly ovate. 
The thin lip advances in the lower-outer part. The basal lip is deeply curved. 
Columella moderately calloused. 
Length, 15.0 mm.; diameter, 5.2 mm.; length of aperture, 5.2mm.; 494 whorls 
remaining. Type. 
Length, 16.3 mm.; diameter, 4.7 mm.; length of aperture, 5.5 mm.; 5 whorls 
remaining. 
Length, 17.0 mm.; diameter, 5.3 mm.; ica ah of aperture, 6.3 mm.; 5 whorls 
remaining. 
This form is very similar to M. lebrechtsi Caines a much 
larger shell, 28X10 mm., with 7 to 9 whorls remaining. We consider it 
distinct mainly on  iaalit of the far smaller size in several lots of 
hundreds of specimens. 
Melanoides kisangani congo, new subspecies 
Plate X XI, Figures 23 and 24 
Stanleyville, near the falls of the Congo River (H. Lang Coll./. 
