1927] Pilsbry-Bequaert, The Aquatic Mollusks of the Belgian Congo 261 
The shape and sculpture vary so much in the considerable series 
seen that we are compelled to include M. soror and M. consobrina 
Dupuis and Putzeys as forms of nsendweensis. 
Melanoides nsendweensis consobrina (Dupuis and Putzeys) 
Plate XXII, Figures 9-11 
Melania consobrina Dupuis anp Purzeys, 1900, Ann. Soc. Malacol. Belgique, 
XXXV, Bull. Séances, p. xviii, figs. 31 and 32. 
Lualaba River at Nsendwe (type locality; Dupuis Coll.). Kindu (J. Bequaert 
Coll.). 
Melanoides nsendweensis consobrina differs by having the two series 
of tubercles more developed: than in typical nsendweensis. Often the 
tubercles of the lower series are bifid. The specimens from Kindu on 
the Lualaba referred to nsendweensis by Dautzenberg and Germain 
belong to this race. 
The specimens figured are respectively 13.5, 11.5, and 11.0 mm. long. 
Melanoides nsendweensis soror (Dupuis and Putzeys) 
Plate XXII, Figure 13 
Melania soror Dupuis AND Purzeys, 1900, Ann. Soc. Malacol. Belgique, XXXV, 
Bull. Séances, p. xviil, fig. <0. DauTzENBERG AND GERMAIN, 1914, Rev. Zool. 
Afric:, EV topnaes j 
Lualaba River at Nsendwe (type locality; Dupuis Coll.). In the same river at 
Nyangwe (J. Bequaert Coll.). 
Melanoides nsendweensis soror is a narrow, rather parallel-sided 
form in which the axial ribs of the later whorls tend to become obso- 
lete except near the suture, where they remain as a series of oblong 
tubercles. In other examples the ribs persist, but the subsutural 
tubercles are more or less defined by a spiral impression. 
Melanoides nsendweensis megalobasis, new subspecies 
Plate XXII, Figures 6 and 12 
Sandbanks of the Tshopo River-near Stanleyville (H. Lang Coll.). 
This is a form having the narrow shape of M. n. soror. On the penultimate and 
next earlier whorls the ribs are deeply impressed below the subsutural tubercles, 
and bear two tubercles below the impression. On the last whorl they are more or less 
obsolete below the subsutural tubercles. The base has about four spirals, of which 
the second from below is very strongly developed, projecting well beyond the others, 
giving the last whorl an angular or carinate basal outline. 
Length, 12.5 mm.; diameter, 4.0 mm.; length of aperture, 4.2 mm.; 4}4 whorls 
remaining. 
