SOUTH AFRICAN MARINE MOLLUSKS. 173 



at the summit and the fourth is somewhat flattened, while that of 

 the rest is evenly rounded. Base openly umbilicated; umbilicus 

 occupying about one- third of the width of the base; bounded by a 

 very slender spiral cord. The space from the base of the ruffle to 

 this cord is evenly well rounded. The entire surface of the base is 

 marked by rather strong lines of growth and microscopic spiral 

 striations. This sculpture extends also into the umbilicus. Aper- 

 ture very oblique, irregularly triangular; posterior angle acute; outer 

 lip rendered denticulated by the external sculpture; inner lip slender, 

 strongly sigmoid, and slightly reflected. 



The type, Cat. No. 250561, U.S.N .M., comes from Port Alfred 

 (Coll. No. 1434). Its greatest diameter is 2.3 mm. 



DISCOPSIS TURTONI, new species. 

 Plate 33, figs. 1, 2, 3. 



Shell small, discoidal, semitranslucent, bluish white. Nuclear 

 whorls one and one-half, smooth, well rounded, forming a depressed 

 helicoid spire with strongly impressed sutures. Postnuclear whorls 

 two and one-fifth, broad, well-rounded, with strongly impressed 

 sutures marked on the upper surface by rather strong, decidedly, 

 retractively curved lines of growth. Periphery of the last whorl 

 acutely keeled. Base very widely, openly umbilicated, there being 

 scarcely any external limit to the umbilicus, all the whorls showing 

 within. A slender spiral cord encircles the base about one-fourth 

 of the distance anterior to the periphery. On the base the lines of 

 growth assume a thread-like appearance, becoming stronger within 

 the umbilicus. The entire base is marked by microscopic spiral 

 striations. Aperture very oblique, of irregular outline; outer lip 

 thin, sinuous, showing the external markings within; inner lip de- 

 cidedly flexuose, thin. 



The type and another specimen, Cat. No. 249766, U.S.N.M., come 

 from Port Alfred (Coll. No. 1038). The type measures: Greatest 

 diameter, 2.5 mm.; lesser diameter, 1.7 mm. 



Genus LEPTOGYRA Bush. 



LEPTOGYRA AFRICANA, new species. 

 Plate 36, figs. 4, 5, 6. 



Shell very minute, semitranslucent, bluish white. Nuclear whorls 

 two, well rounded, smooth, forming a depressed helicoid spire. Post- 

 nuclear whorls well rounded, marked by numerous fine, equal and 

 equally spaced, incised spiral striations of which about 35 occur between 

 the summit and the well-rounded periphery of the last whorl. The 

 axial sculpture consists of fine lines of growth only. Base strongly 

 rounded, somewhat inflated, with a moderately broad umbilicus 

 marked by the continuation of the fine lines of growth, which grow a 

 little stronger as they approach the umbilicus, and on the posterior 



