MARINE MOLLUSCA OF THE UNITED STATES. IST 



mis thick, dark violaceous, blackish, or chestnut-brown ; within 

 pearly. 



Length 4.5-6, height 2.5-3 inclies. 



Animal dark-orange or reddish ; edible. 



Northern Coast, northwards. {Eur.) 



2. M. PLiCATULA, Lamarck. Fig. 512. 



Anim. s. Vert., vii. 23. 1823. 

 M. semicostata, Cour., Journ. Phila. Acad., vii. 344, t. 20, f. 7. 



Shell oblong, obliquely dilated, somewhat falciform; surface 

 with approximated deep fiiri'ows 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 strine; 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 pearl^^, occasionally purple- 

 tinted. 



Length 2.5-4.5, height .8-L5 inches. 



WJiole Coast. 



Inhabits salt marshes, estuaries, and brackish waters. 



3. M. TULiPA, Linnoeus. Fig. 514. 



Modiola Americana., Leach., Zool. Misc., ii. t. 73, f. 1. 1815. 

 'Kofr" Modiola castanea, Say, Journ. Pliilad. Acad., ii. 366. 1823. 



Shell #blong, rather thin, ventricose; hinge margin elevnted in 

 a right line from tlie beak to tlie alated angle, from whicli it de- 

 clines in a right line to nearl}- 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. 



Sout7ier7i Coast. {W. Ind.) 



31. castanea appears in some catalogues as a distinct species, 

 but an author's specimenT in Mus. Philad. Acad, proves its 

 identity with tulijja. 



4. M. CAROLiNENSis, Courad. Fig. 513. 



Journ. Pliilad. Acad., vii. 344, t. 30, f. 6. 1837. 

 Shell dilated in the middle; disks with very numerous radiating 

 strife ; lower margin rounded and beautifully crenulate. Color 

 ' greenish-yellow; within yellowish, spotted with purple. 



Charleston, S. C. 



