SOUTH AFRICAN MARINE MOLLUSKS. 129 



keels is almost flat. Periphery of the last whorl marked by a strong, 

 spiral cord. Base well rounded, marked by three subequal and 

 equally spaced, low, spiral cords. In addition to the spiral marking, 

 the whorls are marked by numerous, very fine lines of growth. Aper- 

 ture broadly ovate; posterior angle obtuse; outer lip thin, showing the 

 external sculpture within; inner lip thin, slightly reflected; parietal 

 wall covered with a thick callus which renders the peritreme complete. 

 The type, Cat. No. 250394, U.S.N.M., comes from Port Alfred 

 (Coll. No. 1267). It has three postnuclear whorls, and measures: 

 Length, 2.1 mm.; diameter, 1.3 mm. 



ALVANIA ARGENTEA Sowerby. 



Four lots of this species are in the collection of the United States 

 National Museum, all from Port Alfred. Cat. No. 186820, two speci- 

 mens (Coll. No. 186). Cat. No. 250393, one specimen (Coll. No. 1266). 

 Cat. No. 250403a, one specimen (Coll. No. 1276). Cat. No. 252279, 

 25 specimens (Coll. No. 1588). In addition to these we have seen 15 

 specimens in Colonel Turton's collection (Coll. No. 1587), and 87 

 specimens in the same collection (Coll. No. 1588). 



ALVANIA FENESTRATA Krausa. 



Three lots of this species are in the collection of the United States 

 National Museum, all from Port Alfred. Cat. No. 186818, five speci- 

 mens (Coll. No. 184). Cat. No. 252278, 25 specimens (Coll. No. 1588). 

 In addition to that we have seen 111 specimens which have been 

 returned to Colonel Turton (Coll. No. 1587). 



ALVANIA IMA, new species. 

 Plate 5, fig. 2. 



Shell small, ovate, yellowish white. Nuclear whorls two, well 

 rounded, smooth. Postnuclear whorls slightly rounded, marked by 

 very regular, feeble, protractive axial ribs which are a little wider 

 than the spaces that separate them. Of these ribs, 26 occur upon the 

 first, 30 upon the second, and 32 upon the penultimate whorl. In ad- 

 dition to the ribs, the whorls are marked by a slender spiral cord at the 

 summit, which renders the summit decidedly crenulated. A second 

 spiral cord marks the periphery of the turns; the intercostal spaces 

 between these spiral cords are wedge-shaped, the angle of the wedge 

 being at the summit. Base somewhat inflated, well rounded, marked 

 on the posterior two-thirds by six strongly incised spiral grooves, 

 which make the spaces between them appear as broad, low rounded 

 keels. Sutures strongly impressed. Aperture irregularly oval ; outer 

 lip moderately thick, showing the external sculpture within; inner lip 

 almost straight, oblique; parietal wall covered with a thick callus. 



