MARINE MOLLUSCA OF THE UNITED STATES. 187 
mis thick, dark violaceous, blackish, or chestnut-brown; within 
pearly. 
Length 4.5-6, height 2.5-3 inches. 
Animal dark-orange or reddish ; edible. 
: Northern Coast, northwards. (Eur.) 
2. M. pLicATULA, Lamarck. Fig. 512. 
Anim. s. Vert., vii. 22. 1822. 
M. semicostata, Cour., Journ. Phila. Acad., vii. 244, t. 20, f. 7. 
Shell oblong, obliquely dilated, somewhat falciform; surface 
with approximated deep furrows radiating towards the dilated 
margin, fainter on the basal margin, but more distinct near the 
beaks, which are often eroded; a few distant, concentric, narrow, 
impressed lines cross the radiating strive; beaks prominent, 
rounded; hinge margin straight, ascending; basal margin concave, 
depressed, with a small fissure for the byssus. Epidermis greenish- 
yellow to reddish-brown; within pearly, occasionally purple- 
tinted. 
Length 2.5—4.5, height .8-1.5 inches. 
Whole Coast. 
Inhabits salt marshes, estuaries, and brackish waters. 
3. M. runrpa, Linneus. Fig. 514. 
Modiola Americana, Leach., Zool. Misc., ii. t. 72, f. 1. 1815. 
Modiola castanea, Say, Journ. Philad. Acad., ii. 266. 1822. 
Shell oblong, rather thin, ventricose; hinge margin elevated in 
a right line from the beak to the alated angle, from which it de- 
clines in a right line to nearly an equal distance, the alar angle 
rounded ; anterior margin short and small; basal margin slightly 
contracted in the middle. Epidermis marked only by growth 
lines, yellowish or brownish, with dark rays over the middle pos- 
terior portion, sometimes uniform chestnut-color. 
Southern Coast. (W. Ind.) 
MI. castanea appears in some catalogues as a distinct species, 
but an author’s specimen in Mus. Philad. Acad. proves its 
identity with éulipa. 
4, M. CAROLINENSIS, Conrad.. Fig. 513. 
Journ. Philad. Acad., vii. 244, t. 20, f. 6. 1887. 
Shell dilated in the middle; disks with very numerous radiating 
strie ; lower margin rounded and-beautifully crenulate. Color 
greenish-yellow ; within yellowish, spotted with purple. 
Charleston, 8S. C. 
