278 Bulletin American Museum of Natural History [Vol. LIIT 
Length, 24.0 mm.; diameter, 14.7 mm.; length of aperture, 12.8 mm.; about 
246 whorls remaining; type. 
Length, 17.2 mm.; diameter, 10.3 mm.; length of aperture, 10.0 mm.; less 
than 2 whorls Teer 
Length, 24.7 mm.; diameter, 13.3 mm.; length of aperture, 15.0 mm.; about 
244 whorls remaining. 
This form is related to P. graptoconus by its minute sculpture, but 
differs by the short contour, the more sinuous outer lip and the strong 
callus covering the inner lip and thickened to form a pad above. 
A series of nine immature melanians from Kai Bumba near Ganda 
Sundi, collected by H. Schouteden, represent young stages of P. schou- 
teden. The specimens measure from 5 to 15.8 mm. long. They have the 
minute sculpture as in adult P. schoutedeni and at and below the periphery 
there are rather strong spiral cords, four on the largest examples, two in 
the smallest. The larger ones have also a group of three cords around 
the columella, the smaller ones none there. 
Potadoma, alutacea, new species 
Plate XX VI, Figures 3 and 3a 
Tshopo River near Stanleyville (H. Lang Coll.), March, 1915, in 
company with P. superba and other species. 
The shell is solid, conic, sharply angular at periphery, the whorls almost flat. 
Surface smooth to the eye, but under a lens minutely, densely granulose, the granules 
not arranged in either spiral or vertical series; also showing indistinct and superficial 
traces of spiral lines. The color is SOW. Aperture ovate, somewhat produced, 
being shortly spout-like at base of the columellar margin. The outer lipis very slightly 
sinuous. Columella but little thickened. Parietal callus moderately thick. 
Length, 26.0mm.; diameter, 11.5mm.; length.of aperture, 12.0 mm.; 444 whorls 
remaining. 
Length, 19.5 mm‘; diameter, 12.0 mm.; length of aperture, 11.0 mm.; 13 
whorls remaining. 
This species was taken with P. superba, P. superba mut. inculta and 
P. mungwana. It differs from the latter by the more conic form and 
especially the minute sculpture. P. alutacea has a surface like pebbled 
leather, while in P. mungwana there are irregular axial strie cut by 
incised spirals, producing a decussate appearance on parts of the shell 
where it is well developed. The peripheral angle of P. alutacea is some- 
what more pronounced than in mungwana. ! 
Potadoma ignobilis (J. Thiele) 
Plate XXVI, Figures 1 and 2~2a 
| ey ignobilis J. Tome, 1911, ‘Wiss. Ergebn. D. Z. Afr. Exp. (1907-08),’ 
TIL, py 21 Ply, fe: 63. 
Type loeality: Ituri River near Mawambi (Schubotz Coll.). 
t 
