142 Transactions of the Royal Society of South Africa. 



Trachycystis cressyi sp. n. 

 (Plate IV, fig. 11.) 



Shell of moderate size, depressed globose, narrowly umbilicate, thin, 

 somewhat hairy, transparent, corneous, yellow-brown. Spire but little 

 raised, though each whorl is clearly visible in profile above the next ; apex 

 obtuse. Whorls 4, regularly increasing, shouldered at the periphery, which 

 is situate well above the median line ; the first 1|- microscopically punctate, 

 after which the sculpture consists of rather distant, oblique, transverse 

 costulae, increasing in distance on the later whorls, the intervals between 

 them being filled with close, very faint, regular transverse, and equally faint 

 and close spiral striae ; the costulae are sparsely furnished on both sides of 

 the shell with irregular, very deciduous, curved spiny hairs ; suture simple, 

 well defined. Aperture f-lunate, peristome simple, acute ; columella weak 

 and concave, margin narrowly reflexed, leaving open the narrow, but deep 

 umbilicus. 



Diam. maj. 5-1, min. 4-5 ; alt. 3-5 ; apert. alt. 2-2, lat. 2-5 mm. 



Hah. L. Marques. District N. of Macequece (type, Cress}^). 



S. Ehobesia. Six miles from Penhalonga (Miss Grey). 



A smaller form than T. fuscocornea Smith, or any of the hairy South 

 African Trachycystes, while the striation is stronger, the umbilicus narrower, 

 and the hairs fewer than in T. fusco-olivacea Smith. 



Trachycystis fossula sp. n. 

 (Plate IV, fig. 12.) 



Shell small, depressed orbicular, umbilicate, thin, silky, pale corneous. 

 Spire and apex almost flat. Whorls 4J, moderately convex, gradually 

 and regularly increasing, rounded at the periphery, the first 1^ punctately 

 microscopically corrugate, remainder sculptured all over with close, regular, 

 straight, hardly oblique, transverse costulae, with about 4 microscopic 

 transverse striae in the intervals ; suture simple, canaliculate. Aperture 

 f-lunate, hardly descending at the base, peristome simple, acute ; outer 

 lip almost straight in profile, columella short and concave, margin not 

 reflexed, umbilicus rather narrow, but deep. 



Diam. maj. 3-3, min. 3-0 ; alt. 2-0 ; apert. alt. 1-5, lat. 1-4 mm. 



Hab. L. Marques. Mount Vengo, 5500 ft. (Cressy). 



More widely umbilicate than T. sericea, and difiering from other small 

 species, such as T. rivularis (Krs.) and ordinaria M. and P., which resemble 

 it superficially, in its sculpture, which is almost at right angles to the suture 

 instead of being considerably oblique, and recalls the larger T. charybdis 

 (Bs.) rather than any of the smaller forms. 



