1927] Pilsbry-Bequaert, The Aquatic Mollusks of the Belgian Congo 283 
' 
distinct in some places, weak or wanting elsewhere. The aperture is ovate. Outer 
lip thin, scarcely sinuous, columella and parietal wall moderately calloused, thick- 
ened to form a low tubercle or callous pad near the posterior angle of the aperture. 
Length, 26.0 mm.; diameter, 10.0 mm.; length of aperture, 10.8 mm.; 5 whorls 
remaining. 
Length, 23.7 mm.; diameter, 9.5 mm.; about 4} whorls remaining. 
A small, very delicately sculptured and deep olive race of the protean 
P. liricincta, similar to that in the minute sculpture. 
Potadoma medjeorum, new species 
Text Figure 47a,-b 
Medje, on anklets worn by children of the Medje tribe (Fig. 49); 
not found living. (Lang and Chapin Coll.). 
a b b c ele 
Fig. 47. Fig. 48. 
Fig. 47. Potadoma medjeorum Pilsbry and Bequaert. a,type and 6, paratype 
Medje. 
Fig. 48. a-d, Potadoma tornata (v. Martens). Copy of original figures. 
The shellis very solid, ovate-turrited, truncate, leaving about 214 whorls in those 
seen, white under a glossy chestnut-brown epidermis. Spire rises in stages on account 
of the concave, partly horizontal shoulder formed by the upper carina, and the rather 
straight-sided whorls. Sculpture of three strong carine at and above the periphery, 
strong spiral cords below it, in all 7 (or sometimes 8) on the last whorl, three on the 
penult, the lower one partly concealed in the suture; on the next earlier whorl the 
lower carina is covered, leaving but two. The last whorl is relatively large. 
The aperture is broadly oval, the basal margin decidedly expanding. Columellar 
margin heavily calloused, with a thicker callus above, separated from the outer lip- 
termination by a shallow furrow. | 
Length, 29.0 mm.; diameter, 18.5 mm.; length of aperture, 16.0mm.; 245 whorls 
remaining; type. | 
Length, 29.5 mm.; diameter, 19.5 mm.; length of aperture, 16.5 mm.; 2 whorls 
remaining. 
With some resemblance to P. tornata (von Martens), figured for 
comparison in Fig. 48a-d, and to the more heavily lirate forms of P. 
