~ 
MARINE MOLLUSCA OF THE UNITED STATES. 149 
4, T. renta, Say. Figs. 350, 351. 
American Conchology, Pl. 65, f. 3. 
Shell small, oval, white; shortest behind, narrowed, much de- 
flected and widely gaping; lines of growth very fine. Two cardi- 
nal teeth in the right and one in the left valve; a posterior lateral 
tooth in the right valve and a corresponding groove in the left. 
Length 15, height 10 mill. . 
Massachusetts to So. Carolina. 
This species is generally larger than J. tenera, and has not its 
polished surface. It differs from others principally in being less 
triangular, more strongly deflected, and in its widely gaping pos- 
terior portion. 
5. T. Mopesta, Verrill. Figs. 352, 353. 
(Angulus.) Am. Journ. Sci., 285, t. 6, f. 2, 2a. 1872. 
Shell smooth, shining, more or less iridescent, with very fine 
concentric strie. Form similar to 7. tenera, but more oblong 
and with the anterior dorsal margin nearly straight or even 
slightly concave; beaks at about the posterior third and scarcely 
prominent; the posterior end slopes rapidly and is subtruncate 
at the end; the ventral margin is but slightly convex in the 
middle, and subparallel with the dorsal margin. Teeth and 
hinge margin stronger than in fenera. Color pink, light straw- 
color or white; often banded concentrically with these colors. 
| New England. 
6. T. mis, Say. Fig. 354. 
Journ. Philad. Acad., ii. 302. 1822. 
Shell very thin and fragile, pellucid, compressed, transversely 
oblong, suboval; minute concentric wrinkles, crossed by oblique 
striz which do not attain the margin; margin narrowed and sub- 
acute; basal edge straight, opposite the beaks. Color, white, 
iridescent, with a rosaceous disk and one or two anterior rays. 
Length 12.5, height 7.5 mill. 
North Carolina, southwards. 
7. T. BREVIFRONS, Say. Figs. 355-357. 
Am. Conchology, t. 64, f. 1. 
Shell oval, thin, and fragile, not very convex, white, tinged 
with pale dull fulvous; with transverse slender strive and obsolete 
radiating ones; deeper colored within; cardinal teeth two in the 
left valve and one in the right valve; lateral teeth none. 
South Carolina. 
