148 AMERICAN MARINE C0NCH0L0GY. 



valve ; lateral teeth none. Muscular impressions strong ; pallial sinus 

 large and broad. Ervilia. 



Genus Tellina, Linnaeus. 

 Syst, Nat., edit. x. 674. 1758. 



1. T. alternata, Say. Fig. 345. 



Journ. Acad. Nat. Sci. Philad., ii. 275. 1822. 



Shell compressed, oblong, narrow and angulated behind ; nume- 

 rous impressed concentric lines, alternately obsolete, on the pos- 

 terior margin. Within, a callous line passes from behind the 

 hinge to the inner margin of the posterior cicatrix. Posterior 

 hinge tooth emarginate ; anterior lamellar tooth near the cardinal, 

 so as to appear like a primary tooth ; that of the right valve 

 wanting ; posterior lamellar tooth at the extremity of the liga- 

 ment. Posterior hinge-slope declining in a concave line to an 

 obliquely truncated tip. "White, tinged with yellow within. 



Length 55, height 31 mill. 



North Carolina to West Indies. 



2. T. polita, Say. Figs. 346, 347, 348. 



Journ. Philad. Acad., ii. 276. 1822. 



Shell transversely subtriangular, with minute concentric wrin- 

 kles ; anterior margin rather shortest ; hinge slope declining in a 

 very slightly arcuated line to a subacute termination; basal 

 margin nearhy straight from before the middle to the posterior 

 end ; a lateral tooth behind the primary one. White immaculate. 



Length 15, height 10 mill. 



North Carolina, southwards. 



3. T. tenera, Say. Fig. 349. 



Journ. Philad. Acad., ii. 303. 1822. 



Shell very thin and fragile, pellucid, compressed, transversely 

 oblong, suboval ; covered by delicate concentric lines of growth. 

 Beaks placed slightly posteriorly ; marginal folds distinct ; basal 

 margin slightly arcuated. Posterior cardinal tooth in the left 

 valve largest ; the other often indistinct ; the chief tooth in each 

 valve grooved ; lateral tooth on the longest side distinct ; the 

 others very indistinct. White, iridescent, occasionally rosaceous. 



Length 14, height 9 mill. 



Nova Scotia to 8. Carolina. 



Found abundantly on sandy beaches, and probably lives not 

 far from low-water mark. 



