1927] Pulsbry-Bequaert, The Aquatic Mollusks of the Belgian Congo 323 
anatomy is practically identical. It differs from Paramelania only in 
the more produced ends of the peristome and this varies considerably in 
specimens seen. 
Paramelania (Bythoceras) iridescens (J. E. S. Moore) 
Text Figure 67a-c 
Bythoceras iridescens J. HZ. S. Moore, 1898 (March), Proc. Roy. Soc. London, 
LXII, p .452, fig. 1; 1898 (March), Quart. Jl. Micr. Sci., N.S., XLI, p. 307; 1898 
(July), Proc. Malacol. Soc. London, III, 2, p. 98, fig. 1; 1903, ‘The Tanganyika 
Problem,’ pp. 2387-248, figs. 21-23. Nicoxas, 1899, C. R. Assoc. Frang. Avance. Sci., 
(1898), IT, p. 525, fig. 9. E. A. Smrra, 1904, Proc. Malacol. Soc. London, VI, 2, p. 86; 
1906, Proc. Zool. Soc. London, I, p. 182, Pl. x, figs. 1-3. Ancry, 1907, Bull. Scientif. 
France et Belgique, (5) IX, (1906), p. vasa 
Lake Tanganyika: Susi. in the southern portion, alive at a depth of 600-700 
ft. (type locality; J. E. 8. Moore Coll.); Niamkolo, at the southern end (W. A. 
Cunnington Coll.). } 
Stappers obtained this species in the bay of Kilewa, bay of the Luvu, the region 
of Kituta, off Uvira, off Moliro, bay of Sumbu, and near the delta of the Ruzizi River. 
Paramelania (Bythoceras) minor (J. E. S. Moore) 
Bythoceras minor J. KE. S. Moore, 1903, ‘The Tanganyika Problem,’ p. 242, fig 
24, and p. 244. E. A. Smrru, 1904, Proc. Malacol. Soc. London, VI, 2, p. 86, fig. 1. 
(on p. 87); 1906, Proc. Zool. Soc. London, I, p. 182, Pl. x, fig. 4. 
Lake Daigeucir lene originally described from the lake without more definite 
locality (J. E. S. Moore Coll.); Tembwe, on the western coast (W. A. Cunnington 
Coll.). 
In 1906, E. A. Smith was of opinion that B. minor would eventually prove to be 
@ variety of Paramelania crassigranulata EK. A. Smith. 
Lavigeria GROUP 
Shell elongate or ovate, with spiral sculpture and axial folds. Operculum scarcely 
spiral, with subbasal, marginal nucleus. Side teeth of the radula short, the inner one 
with few cusps (3 in L. grandis), outer with numerous denticles. 
Probably the genera Joubertia, Lavigeria, and Randabelia are not 
really separable. Their shell characters are much the same. According 
to Dautzenberg, Hirthia is to be added. We have seen only Lavigeria 
and Joubertia. Lavigeria has been dissected, but the anatomy and 
opercula of the other supposed genera are unknown. 
Edgaria has an operculum of the same type as Lavigeria, but wider 
and oval. The shell differs chiefly by its rounded, evenly concave colu- 
mella. The position of Lechaptoisia is doubtful, as only the shell is 
known. | 
These are mollusks of the littoral zone, often very abundant. 
