192 BULLETIN 91, UNITED STATES NATIONAL MUSEUM. 



little wider than the spaces that separate them. Interior showing 

 the external sculpture through the substance of the shell. Entire 

 inner basal margin marked by alternating squarish teeth and 

 depressions, forming a series of sockets and teeth which alternate in 

 the opposing valves. The character of the hinge is shown in our 

 detailed figure. 



The type and another valve, Cat. No. 251049, U.S.N.M., come 

 from Port Alfred (Coll. No. 1566). The type measures: Altitude, 1.2 

 mm.; length, 1.2 mm. 



Family CARDITIDAE. 



Genus CARDITA Bruguiere. 



CARDITA VARIEGATA TURGIDA Krauss. 



Cat. No. 32055, U.S.N.M., one specimen from the Cape of Good 

 Hope. Cat. No. 43172, U.S.N.M., two valves from the Cape of 

 Good Hope. 



CARDITA (CARDITAMERA) LATICOSTATA Smith. 



Cat. No. 186929, U.S.N.M., four valves from Port Alfred (Coll. 

 No. 299). Cat. No. 251010, two valves from the same locality (Coll. 



No. 1527). 



Genus VENERICARDIA Lamarck. 



VENERICARDIA ELATA Sowerby. 



Cat. No. 186931, U.S.N.M., two specimens from Port Alfred (Coll. 

 No. 301). 



VENERICARDIA AFRICANA, new species. 

 Plate 48, fig. 3; plate 54, figs. 5, 6. 



Shell small, rather thick, rose colored. Umbones bent decidedly 

 forward, forming a rather strong-pointed hook. Surface marked by 

 12 strong, rounded, radiating ribs, of which the central ones are the 

 heaviest. These ribs give the ventral edge a somewhat fluted ap- 

 pearance. In addition to these radiating ribs, the shell is marked 

 with strong, concentric, sublamellar threads, which pass equally strong 

 over the ribs and the intercostal spaces. The character of the hinge 

 is shown in our detailed sketch. 



Cat. No. 187171, U.S.N.M., contains the type, which comes from 

 Port Alfred (Coll. No. 720). It measures: Altitude, 3.1 mm.; length, 

 2.8 mm. 



Cat. No. 251012, U.S.N.M., contains two additional valves from the 

 same locality (Coll. No. 1529). 



Genus THECALIA H. and A. Adams. 



THECALIA CONCAMERATA Bruguiere. 



Cat. No. 137, U.S.N.M., 12 specimens collected by William Stimpson 

 on the North Pacific exploring expedition at the Cape of Good Hope. 



