198 BULLETIN 91, UNITED STATES NATIONAL MUSEUM. 



ance. The surface markings consist of somewhat irregularly spaced 

 and developed fine lines of growth, and microscopic, radiating stria- 

 tions. The character of the hinge is shown in the detailed sketch. 



The type, Cat. No. 251041, U.S.N.M., comes from Port Alfred 

 (Coll. No. 1558). It measures: Altitude, 3 mm.; length, 3.5 mm. 



ERYCINA RIFACA, new species. 

 Plate 39, fig. 3; plate 50, figs. 7, 8. 



Shell very minute, subcircular, with the umbones median. Outer 

 surface covered by an exceedingly thin periostracum which lends it 

 an iridescent appearance. The outer surface is marked by exceed- 

 ingly fine lines of growth only. The prodissoconch is strongly con- 

 stricted at its junction with the succeeding portion of the shell. The 

 character of the hinge is shown in the detailed figure. 



The type and another specimen, Cat. No. 251068, U.S.N.M., come 

 from Port Alfred (Coll. No. 1585). The type measures: Altitude, 1 

 mm. ; length, 1 .2 mm. 



ERYCINA, species? 



Cat. No. 251039, U.S.N .M., contains a single valve of a rather large 

 triangular species, from Port Alfred, which we are unable to identify 

 (Coll. No. 1556). 



ERYCINA, species ? 



Cat. No. 187195, U.S.N .M., contains a single worn valve of another 

 species from Port Alfred, which we are also unable to identify (Coll. 

 No. 746). 



Genus BORNIA Philippi. 



BORNIA FORTIDENTATA Smith. 

 Plate 50, figs. 9, 10. 



Cat. No. 186970, U.S.N.M., contains three specimens from Port 

 Alfred (Coll. No. 343). Cat. No. 186971, U.S.N.M., contains three 

 additional specimens of this species from the same locality (Coll. No. 

 344). 



BORNIA FARICA, new species. 

 Plate 41, fig. 6; plate 51, figs. 1, 2. 



Shell small, subcircular, thin, bluish white. Umbones decidedly 

 anterior to the middle. Outer surface marked by numerous, closely 

 spaced, concentric threads which are separated by grooves about as 

 wide as the threads. The character of the hinge is shown in our 

 detailed sketch. 



The two cotypes, Cat. No. 251061, U.S.N.M., representing two 

 opposite valves, come from Port Alfred (Coll. No. 1578). The larger 

 of these measures: Altitude, 2.5 mm.; length, 3 mm. 



