SOUTH AFRICAN MARINE MOLLUSKS. 131 



RISSOINA EUCOSMIA, new species. 

 Plate 20, fig. 2. 



Shell small, falcate, semitranslucent. Nuclear whorls a little 

 more than one, smooth, well rounded. Postnuclear whorls high 

 between the sutures, strongly shouldered at the summit, marked on 

 the anterior half by strong, comma-shaped axial ribs, which are 

 truncated posteriorly, tapering gently anteriorly and are lost before 

 they reach the middle of the whorl. Of these ribs, 12 occur upon 

 the first, 14 upon the second, 16 upon the third, and 18 upon the 

 fourth and penultimate turn. In addition to these axial ribs the 

 whorls are marked between the sutures by a smooth spiral cord, 

 the posterior border of which marks the space between the sutures 

 on the later turns. Sutures strongly channeled. Periphery of the 

 last whorl marked by a strong spiral cord. Base moderately long, 

 marked by two, equal and equally spaced, spiral cords, of which the 

 last encircles the insertion of the columella. Aperture oval; outer 

 lip thick, with a brown band immediately posterior to the spiral 

 keel; inner lip very thick and appressed to the attenuated base; 

 parietal wall covered by a moderately thick callus which renders the 

 peritremo complete. 



The type, Cat. No. 250395, U.S.N.M., comes from Port Alfred 

 (Coll. No. 1268). It has five and a half postnuclear whorls, and 

 measures: Length, 2.8 mm.; diameter, 1.1 mm. 



RISSOINA, species? 



Cat. No. 250372, U.S.N.M., contains the tips of two Rissoinas, 

 from Port Alfred, too young to be determined (Coll. No. 1245). 



Cat. No. 250400, U.S.N.M., contains a Rissoina from Port Alfred, 

 which is different from any of the known species, but too poor to 

 serve for a diagnosis (Coll. No. 1273). 



RISSOINA (PHOSINELLA) PUR A Gould. 

 Plate 5, fig. 10. 

 Alvania pura Gould, Proc. Bost. Soc. Nat. Hist., vol. 7, p. 402, 1861. 



Shell elongate-conic, white. Nuclear whorls two, well rounded, 

 smooth. Postnuclear whorls well rounded, marked by almost ver- 

 tical narrow axial ribs which are about one-half as wide as the spaces 

 that separate them. Of these ribs 12 occur upon the first, 18 upon 

 the second to fourth, 20 upon the fifth, 22 upon the sixth, and 26 

 upon the penultimate whorl. In addition to the axial ribs the 

 whorls are marked by equal and equally spaced spiral cords which are 

 almost as strong on the ribs, the junctions of the two forming strong, 

 rounded tubercles. Of these cords, 2 occur upon the first, 3 upon 

 the second to fourth, and 5 upon the remaining turns. The spaces 



