SOUTH AFRICAN MARINE MOLLUSKS. 169 



Genus CYCLOSTREMA Marryat. 



CYCLOSTREMA ALFREDENSIS, new species. 

 Plate 35, figs. 6, 7, 8. 

 Shell small, milk white. Nuclear whorls two and one-half, well 

 rounded, smooth. Post-nuclear whorls marked by four strong 

 spiral keels, of which the first, which is the weakest, is a little anterior 

 to the summit, while the second marks the very strong shoulder, 

 the fourth forming the peripheral keel, and the third being half way 

 between the second and the periphery. In addition to these spiral 

 cords the whorls are marked by decidedly retractively slanting axial 

 riblets which increase in strength and spacing as the shell progresses 

 in size. About 25 of these occur on the last half of the last turn. 

 These riblets cross the sulci, which are about twice as broad as the 

 spiral cords, but do not seem to pass over the spiral cords. Periphery 

 rendered angulated by the peripheral cord. Base well rounded, 

 marked by three spiral cords, of which, the third and strongest bounas 

 the moderately large umbilicus ; the other two divide the space between 

 this and the peripheral cord into three equal parts. The deep sulci 

 are marked by the continuation of the axial riblets. Aperture 

 oblique, subcircular; outer lip rendered decidedly sinuous at the 

 margin by the external sculpture, which is also apparent through 

 the substance of the shell; inner lip oblique, slightly curved and 

 slightly reflected. 



The type, Cat. No. 250501a, U.S.N.M., comes from Port Alfred 

 (Coll. No. 1374). It has one and one-fifth postnuclear whorls, and 

 measures: Altitude, 1.2 mm.; greater diameter, 1.7 mm. 



Genus CYCLOSTREMELLA Bush. 



CYCLOSTREMELLA FARICA, new species. 

 Plate 32, figs. 7, 8, 9. 

 Shell small, depressed helicoid, very thin, translucent, bluish 

 white. Nuclear whorls a little more than one, well rounded, smooth. 

 The first half postnuclear whorl is ornamented with a strong keel a 

 little anterior to the summit and another a little posterior to the 

 periphery; the spaces between the keel and the summit, and between 

 the keels are finely striated. These striations become stronger and the 

 keels less pronounced after passing the first half turn, until on the 

 final whorl the shell is marked with numerous equal and equally 

 spaced fine spiral lirations, of which the first two near the summit 

 are a little weaker than the rest and give this narrow portion almost 

 the appearance of a smooth band. About 40 of these lirations occur 

 between the summit and the periphery. Sutures well impressed. 

 Periphery well rounded. Base strongly rounded, with a broad 

 umbilicus which extends over half of the diameter of the base. The 

 outer limit of the umbilicus is marked by a strong spiral cord; another 



