7 



American Tertiary Shells 



7 



Genus CORBULA Bruguiere 

 Anapteris, new subgenus 



Description. — Lesser or left, only valve known ; large, flat, 

 surface of shell strongly corrugated, this corrugation extends 

 to the anterior margin where the extreme, anterior portion of the 

 valve appears as though it had been broken ; on the interior of 

 the shell this area corresponds to a wing or flare which is bounded 

 below by a strong ridge ; this ridge suggests the original margin 

 of the valve. The wing bears very fine, radiating striae. 



Anapteris regalis, n. sp., PI. i Fig. 1,3 



Description. — Size and shape of shell as indicated by the fig- 

 ures. Left valve nearly flat, thick, dorsal margin bent out- 

 ward, giving intimation of a gape ; a pronounced carina extends 

 from the beak to the posterior margin. Surface ornamented with 

 prominent, concentric lines which extend from the umbonal 

 ridge to the anterior end where they terminate in a peculiar 

 manner as though the anterior end had been broken ; on the 

 posterior portion of the shell anterior to the umbonal ridge where 

 the lines merge into the ridge a separation of the lines occurs 

 giving place to very short, equally prominent, surface markings. 

 Just anterior and parallel to the umbonal carina is a fine channel ; 

 the prominent lines posterior to the umbonal ridge extend almost 

 vertically to the dorsal margin. On some specimens two slight 

 channels are noted which are situated between the dorsal margin 

 and the posterior ridge and extend from the beak to the poster- 

 ior margin ; on the anterior internal surface of the left valve a 

 raised margin-like ridge extends from the beak concavely, 

 and then rounds into the ventral margin ; the portion of the shell 

 dorsal to the ridge has the appearance of a flare or wing. The 

 projecting, cartilage process in the left valve in this form differs 

 from that in the genus Corbula, in having only a very narrow, 

 short, posterior groove ; the anterior groove is slightly marked, 

 in some cases practically obsolete. 



Types and specimens figured '. — Paleontological Museum, Cor- 

 nell Univ. 



