SOUTH AFRICAN MARINE MOLLUSKS. 133 



numerous, decidedly retractive, incremental lines and exceedingly fine 

 spiral striations. Sutures moderately impressed; periphery of the 

 last whorl inflated, well rounded; base short, narrowly umbilicated, 

 well rounded. Aperture subcircular; posterior angle obtuse; outer lip 

 thin; inner lip strongly curved and partly reflected over the umbilicus, 

 continuing as a thin callus over the parietal wall. 



The type and seven specimens, Cat. No. 187072, U.S.N.M., came 

 from Port Alfred (Coll. No. 610). The type has a little more than 

 five whorls, and measures: Length, 2.1 mm.; diameter, 1.1 mm. Cat. 

 No. 227745, U.S.N.M., contains three specimens from the same locality 

 (Coll. No. 840). Another specimen, Cat. No. 250428, U.S.N.M., also 

 comes from Port Alfred (Coll. No. 1301). 



MICROSETIA HELGA, new species. 

 Plate 6, fig. 3. 



Shell small, elongate-conic, yellowish white. Nuclear whorls not 

 differentiated from the succeeding turns ; all the whorls well rounded, 

 appressed at the summit, through which the preceding whorl shines, 

 which lends the shell the aspect of having a double suture. Sutures 

 moderately impressed. Periphery of the last whorl somewhat in- 

 flated, well rounded. Base moderately long, narrowly umbilicated, 

 well rounded; entire surface of spire and base marked by exceedingly 

 fine incremental lines only. Aperture oval; posterior angle obtuse; 

 outer lip thick; inner lip strongly curved and quite thick, reflected 

 over the umbilicus; parietal wall covered with a thick callus. 



The type and another specimen, Cat. No. 187056, U.S.N.M., came 

 from Port Alfred (Coll. No. 594). The type has six whorls and meas- 

 ures: Length, 2.7 mm.; diameter, 1.5 mm. Cat. No. 250423, U.S.N.M., 

 contains another specimen from Port Alfred (Coll. No. 1296). 



MICROSETIA IRMA, new species. 

 Plate 21, fig. 9. 



Shell elongate-ovate, very thin, transparent. Nuclear whorls not 

 differentiated from the postnuclear turns. Postnuclear whorls well 

 rounded, appressed at the summit, marked by exceedingly fine, re- 

 tractive lines of growth and closely spaced, microscopic spiral stria- 

 tions. Sutures moderately constricted. Periphery of the last whorl 

 strongly rounded. Base moderately long, strongly rounded, very 

 narrowly umbilicated. Aperture ovate; posterior angle acute; outer 

 lip very thin; inner lip very thin, evenly curved and slightly reflected; 

 parietal wall glazed with a thin callus. 



The type and another specimen, Cat. No. 249724, U.S.N.M., come 

 from Port Alfred (Coll. No. 996). The type has four whorls, and 

 measures: Length, 1.6 mm.; diameter, .1 mm. 



80737°— Bull. 91—15 10 



