170 BULLETIN 91, UNITED STATES NATIONAL MUSEUM. 



equally strong is about as far within the umbilicus as it is separated 

 from the first of the five additional spiral cords which mark the inner 

 umbilical wall. The space between the outer limiting cord and the 

 periphery is marked by fine spiral lirations, equaling those on the 

 spire in strength and spacing. Aperture subcircular; outer lip thin, 

 showing the external sculpture within ; inner lip strongly curved and 

 slightly reflected. 



The type, Cat. No. 250556, U.S.N.M., comes from Port Alfred 

 (Coll. No. 1429). It has one and one- third postnu clear turns, and 

 measures: Altitude, 1 mm.; greater diameter, 1.5 mm. 



CYCLOSTREMELLA AFRICANA, new species. 

 Plate 29, figs. 1, 2, 3. 



Shell purplish pink, obscurely dotted and flecked with white except- 

 ing the nuclear whorls, which are of yellowish horn color. Nuclear 

 whorls two and one-half, smooth, forming a depressed helicoid spire. 

 Postnuclear whorls well rounded, appressed at the summit, marked 

 by many equal, and subequally spaced, fine, spiral lines which are 

 about one-fourth as wide as the spaces that separate them. In 

 addition to the spiral sculpture, the whorls are marked by fine lines 

 of growth and irregularly distributed, strong, depressed lines which 

 appear as feeble varicial markings. Sutures well marked. Periphery 

 of the last whorl rounded. Base well rounded, very broadly, openly 

 umbilicated, marked like the spire by fine, incised spiral lines and the 

 axial sculpture, the strong impressed axial lines becoming accentu- 

 ated at the umbilicus, rendering the outer umbilical edge strongly 

 notched. Aperture subcircular; posterior angle slightly channeled; 

 outer lip joining the basal lip in a strong, even curve; inner lip 

 moderately thick, slightly revolute; parietal wall covered with a thick 

 callus which is so developed as to give the aperture the appearance 

 of being notched at this place. 



The type and another specimen of this species, Cat. No. 187101, 

 U.S.N .M., come from Port Alfred (Coll. No. 645). The type has a 

 little more than one and one-half postnuclear whorls, and measures: 

 Altitude, 1.7 mm.; greater diameter, 2.1 mm. 



CAPORBIS, new genus. 



Shell very small, sinistral, planorboid, marked with numerous 

 lamellar, closely spaced, axial ribs. 

 Type. — Caporbis africana. 



CAPORBIS AFRICANA, new species. 

 Plate 35, figs. 1, 2, 3. 



Shell planorboid, sinistral, very small, bluish white, semitrans- 

 lucent. Early whorls completely covered by the succeeding turns 

 on the upper surface, where the last turn only is visible. This is 

 marked by strong lamellar ribs which are decidedly sinuous and have 



