102 



United States. Cabinet of the Academy and Philadelphia Mu- 

 seum. 



A very common shell on almost all parts of our coast. 



Mactra oblonga. — Shell transverse, oblong-oval ; very slightly 

 wrinkled, excepting upon the margin ; umbo hardly prominent ; two 

 strong distant lines or folds drawn from the apex to the anterior 

 extremity of the shell ; color dull whitish, hardly polished, umbo 

 slightly tinged with ferruginous, within white, highly polished. 



Length nine-twentieths of an inch. Breadth one inch and 

 nine-tenths. Inhabits the coast of Greorgia. Cabinet of the 

 Academy and Philadelphia Museimii. 



Of this species I found but three valves, on one of the sea 

 islands of Greorgia. 



Lutraria lineata. — Shell transversely suboval, thin white, 

 tinged with ferruginous; posterior hiatus patulous, anterior one 

 linear and commencing below the hinge slope ; hinge slope with a 

 rectilinear profile, and flattened, oblong-sub cordate surface ; valves 

 unequally wrinkled ; posterior margin rounded, short, with a re- 

 fleeted edge, and submarginal carinated line ; within undulated, 

 anterior margin glabrous, and with an indented submarginal line 

 corresponding with the exterior carinated one. 



Length one inch and nine-tenths. Width two inches and seven- 

 tenths. Thickness one inch and one-twentieth. Inhabits the 

 coasts of Georgia and East Florida. Cabinet of the Academy and 

 Philadelphia Museum. 



Not uncommon on the southern coast, and may be readily dis- 

 tinguished by the carinated line on the posterior submargin. 



Lutraria canaliculata. — Shell transversely oval-orbicular, 

 very thin and fragile, white, inflated j valves equally, concentri- 

 cally, and regularly grooved, very feint parallel lines within the 

 grooves ; posterior margin short, subcuneiforni, compressed ; a mar- 

 ginal, longtudinal, irregular, subimpressed line, between which 

 and the edge the grooves become mere wrinkles ; posterior slope 

 subrectilincar, hiatus considerable ; anterior margin regularly 

 curved, the slope convex ; within grooved as without, anterior 

 angle glabrous. 



Greatest length two inches and one-tweutieth. Breadth two in- 

 ches and a half. Thickness one inch and one-fourth. Inhabits 

 the coast of the United States. Occurs on the coast of Maryland 



