1927] Pilsbry-Bequaert, The Aquatic Mollusks of the Belgian Congo 309 
Solid, ovate-conic, imperforate shells, usually brownish with light subsutural 
band, either smooth or having very fine and superficial spiral sculpture. The last 
whorl rising a little, then descending to the aperture. Peristome slightly expanded 
outwardly and more or less thickened. The inner lip thickened, regularly concave. 
Columella often bordered outwardly by a narrow, lunate, flattened or concave area. 
The operculum (in B. (Giraudia) preclara) “consists of a single 
whorl, the nucleus being subcentral, but nearer the lower end; it is 
sub-ovate, being rather narrower below than above.’ — 
According to Pelseneer, “the radula of Giraudia is clearly similar 
to that of the melaniid genus Ancylotus [=Anculosa Say]. The two 
species G. preclara Bourguignat and G. [Reymondia] horei (Smith) have 
radulz so different in structure as to perhaps necessitate their allocation 
to two distinct genera.” | | 
B. (Giraudia) preclara lives on rocks in shallow water. 
The conchological features are so similar in the supposed genera 
Baizea, Coulboisia, and Giraudia that it appears absurd to accept all as 
genera until distinctions are found to exist in opercula or soft parts. We 
leave them as subgenera for the moment. 
The special character of Baizea proper is the possession of a narrow, 
flattened or concave, lunate area bordering the columella. This appears 
occasionally in old individuals of almost any species of Baizea, Coul- 
boisia, or Reymondia, and a similar structure is often seen in various 
Amnicolide. It has very little systematic value. 
Subgenus BaizgEa, proper 
| Baizea giraud: Bourguignat 
Baizea giraudi BourauiaNnat, 1885, ‘Notice Prodrom. Moll. Giraud Tan- 
ganika,’ p. 34; 1888, ‘Iconogr. Malacol. Tanganika,’ Pl. rv, figs. 17-19; 1890, Ann. - 
Sc. Nat. Zool., (7) X, p. 60, Pl. rv, figs. 17-19. G. B. Sowrrsy, 1894, ‘List of Shells 
of Lake Tanganyika,’ p. 2, Pl., fig. 12. Ancry, 1894, Bull. Soc. Zool. France, XIX, 
p. 28. E. v. Martens, 1897, ‘Deutsch Ost Afr., IV, Beschalte Weichth.,’ p. 205. 
E. A. Smiru, 1904, Proc. Malacol. Soc. London, VI, 2, p. 94. Ancry, 1907, Bull. 
Scientif. France et Belgique, (5) IX, (1906), p. 255. 
Lake Tanganyika: Kapampa (type locality). 
Baizea leucoraphe (Ancey) 
Text Figure 61 
Ponsonbya leucoraphe ANcEY, 1890, Bull. Soc. Malacol. France, VII, p. 347. E. v. 
Martens, 1897, ‘Deutsch Ost Afr., IV, Beschalte Weichth.,’ p. 296. 
1}. A. Smith, 1906, Proc. Zool. Soc. London, I, p. 183. The figure given by Smith does not agree 
with his description. 
