1927] Pilsbry-Bequaert, The Aquatic Mollusks of the Belgian Congo 177 
upper part as in the ioe ; chestnut colored within, becoming whitish and showing 
bands toward the lip. The columellar margin is but slightly oprnded: Adnate 
portion of the i inner lip rather short. 
Length, 37.0 mm.; diameter, 32.0 mm.; length of aperture, 26.0 mm. Lype: 
mane 7h es 23.0 vine ae si 18.4 Paratype 
The operculum has a silvery sheen inside. The scar is large, occupy- 
ing about half the total width, the smooth area in it narrow or very 
narrow. The sculptured area toward the columellar side is finely 
marked with irregular, concentric ridges; that outside of the smooth 
area has at first some intricate areoles, then a few weak concentric 
ridges. The length of the scar is two-thirds that of the operculum or 
somewhat more. | 
The minute sculpture of the shell is characteristic. It resembles 
that of Saulea vitrea (Born), and is far finer than that of Afropomus 
balanoideus (Gould). By size and sculpture it appears most nearly re- 
lated to Pila africana (v. Martens), from Abetifi and Akra, on the Gold 
Coast. The chief difference noticed from the description is the diverse 
color and the presence of bands in all specimens of the Stanleyville 
shell. This, too, is umbilicate rather than perforate, as africana was 
described. 
| The shell is much more solid fae in young specimens of P. con- 
goensis; it is more distinctly sculptured, and the scar of the operculum is 
relatively much larger. 
Pila congoensis, new species 
Plate XV, Figures 3 and 4 
Stanleyville (type locality), about 60 specimens; Niangara, 15 
specimens (Lang and Chapin Coll.). Avakubi, 2 young specimens (J. 
Bequaert Coll.). 
The shell is rather large, inflated, with a large, open umbilicus. Spire moder- 
ately produced, corroded. The whorls are strongly convex, narrowly flattened 
below the deep suture, the last whorl evenly convex, not tapering downward. The 
surface is glossy, under a strong lens showing very weak, microscopically granular, 
spiral strie in some places, marked with slight growth striz. Isabella color with some 
darker brownish streaks and rather indistinct narrow olive bands. The aperture is 
ovate, wide, showing many chestnut bands on a light ground tinged with pink or 
yellowish; becoming suffused with chestnut in the throat. On the slightly expanding 
peristome the bands are more vivid. The columella is little thickened and very little 
expanded, yellowish or orange colored. The adnate portion of the inner lip is very short, 
contained 2}4 times in length of aperture. 
Length, 63.0 mm.; diameter, 58.0 mm.; aperture, 45.0X31.0 mm. Type. 
Se 59.0 « 46. 0X83. 0 
