SOUTH AFRICAN MARINE MOLLUSKS. 149 



by a scarcely perceptible suture, forming a depressed apex. Post- 

 nuclear whorls well rounded, the first ornamented with three spiral 

 cords which are about one-third as wide as the spaces that separate 

 them' and which divide the spaces between the sutures into four 

 equal portions. On the last turn the spiral cords have increased to 

 six which are equal and almost equally spaced. In addition to the 

 spiral sculpture, the whorls are marked by numerous, feeble, de- 

 cidedly retractive lines of growth. Sutures strongly impressed. 

 Periphery of the last whorl well rounded. Base short, well rounded, 

 narrowly unibilicated, marked by six spiral cords which equal those 

 on the spire in strength with the exception of the anterior one which 

 is much weaker than the rest. Aperture oval; outer lip very thick 

 showing the exterior marking within by transparent light. Inner lip 

 exceedingly thick, decidedly curved, partly reflected over and 

 appressed to the base. 



The type and another specimen of this species Cat. No. 186865, 

 U.S.N.M., come from Port Alfred (Coll. No. 235). The type has two 

 postnuclear whorls, and measures: Altitude, 2.4 mm.; greater diame- 

 ter, 3.3 mm. 



This species recalls Leptothyra sanguined Linnaeus, and may be what 

 has been reported from South Africa under this name. It differs 

 from sanguined by having the nuclear whorls white and in bemg um- 

 bilicated in the adult stage, also in detail of sculpture, but most 

 conspicuously by its minute size. Cat. No. 272266, U.S.N.M., con- 

 tains eight specimens from Algoa Bay. 



LEPTOTHYRA ALFREDENSIS, new species. 



Plate 32, figs. 1, 2, 3. 



Shell creamy yellow. The sculpture of the nuclear whorls is worn 

 too badly to be determined. That of the first postnuclear turn 

 consists of a very slender thread at the appressed summit, and three 

 strong spiral keels, of which one is at the periphery, another about 

 one-third of the distance between the summit and the suture, anterior 

 to the summit, while the median one is a little nearer to the peri- 

 pheral keel than the one below the summit. In addition to these 

 strong spiral cords, the whorls are marked by fine, raised, spiral threads, 

 of which eight occur on the concave shoulder between the summit 

 and the strong keel below it, and five between the first keel and the 

 median, and three between the median and the peripheral. In the 

 latter case the middle one is fully twice as strong as the two slender 

 threads bordering it. The base of the last whorl is marked by three 

 strong spiral keels which divide the space between the peripheral 

 keel and the umbilical region into four equal broad grooves, which 

 are also marked with fine spiral threads, two occuring on the first 

 and second below the periphery, and five between the second and 

 80737°— Bull. 91—15 11 



