MARINE MOLLUSCA OF THE UNITED STATES. 153 



Genus TELLIDOEA, Morch. 

 1. T. LUNULATA, Holmes. Figs. 371-3. 



Post Plioc. Fossils S. Car., 47, t. 9, f. 7. 1860. 



Shell subtriangular, inequivalve, inequilateral ; surface of valves 

 concentrically plicated ; beaks prominent, slightly curved later- 

 ally ; lateral slopes strongly produced, dentated at their edges ; 

 two primary teeth in the right valve, one in the other; lateral 

 teeth two in each valve. 



No. Carolina, southwards. (Living.) 



Genus GASTRANELLA, Verrill. 

 1. G. TUMIDA, Yerrill. Figs. 374, 375. 



Am. Journ. Science, iii. 286, t. 6, f. 3. 1872. 



Shell small, variable in form, swollen above, more or less elon- 

 gated, oval or oblong, with rounded ends, compressed posteriorly. 

 Beaks rounded, somewhat prominent, incurved, but not approxi- 

 mate, and directed somewhat forward ; anterior dorsal margin 

 deeply concave in front of the beaks, but without a distinct 

 lunule, at the anterior end regularly rounded or a little prolonged, 

 compressed ; ventral margin slightly convex, or nearly straight 

 and subparallel with the dorsal margin, or incurved, in the differ- 

 ent specimens ; posterior end broadly rounded in some, decidedly 

 prolonged in others; dorsal posterior margin usually nearly 

 straight for at least half its length, sometimes a little convex and 

 gradually sloping throughout. Surface with fine somewhat ir- 

 regular, concentric striae, slightly iridescent. White, with the 



umbones purple. 



Long Island Sound, near New Haven, Conn. 



This species appears to be a " nestler" and quite variable in 

 form. About 20 specimens were obtained of different sizes ; one 

 of the largest, which may not be mature, is .18 of an inch long, 

 .09 high, and about the same in thickness. In 4-6 fathoms, 

 shelly and gravelly bottom, among hydroids and sponges. 



Genus DONAX, Linnaeus. 

 Syst. Nat., edit. x. 682. 1758. 



1. D. FOSSOR, Say. Figs. 376, 377. 



Journ. Philad. Acad., ii. 306. 1822. 

 Donax angustatus, Sowerby. Thes. Conch. Monag. Donax. 



Shell subtriangular, anterior margin short and rounded. Pos- 

 terior hinge-slope straight ; the base very slightly prominent be- 



