66 



EAST COAST MARINE SHELLS 



yellowish, exterior dull; anterior end 

 wing-like, pointed, flaring so that shell 

 gapes; pallial line, inside shell, glossy 

 against an otherwise dull surface, 



PI. E6, Fig. 2 



New Jersey to Texas; Brazil 



Family Mesodesmatidae 



GENUS MESODESMA Deshayes 1830; 

 CERONIA GRAY 1855 



Shell oval, wedge-shaped, cut off 

 at posterior end; lateral teeth compressed 

 and furrowed. 



MESODESMA ARCTATA Conrad. Shell very in- 

 equilateral, wedge-shaped; epidermis yel- 

 low and shining; umbones slightly ele- 

 vated; deep spoon-shaped cavity in hinge 

 for the cartilage: cardinal tooth V-shaped 

 and placed at an angle; straight lateral 

 teeth on each side with striated surfaces. 

 Length 1.5 inches or more. 



It is not infrequently found upon 

 the beaches in considerable numbers, es- 

 pecially upon the outer shores of Cape 

 Cod. 



PI. 6, Fig. 8 



PI. 26, Fig. 9 



Gulf of St. Lawrence to New Jersey 



GENDS ERVILIA Tiirton 1822 



ERVILIA CONCENTRICA Gould. Shell small, 

 white or yellowish, compressed, vunbones 

 close together and not prominent; concen- 

 tric sculpture weak. Length 5 mm. 



Specimens in the National Collec- 

 tion were collected near Loggerhead Key, 

 Florida. 



PI. 26, Fig. 11 



Cape Hatteras, North Carolina to 



the Florida Keys and at Pensacola, 



Florida 



ERVILIA NITENS Montagu. Shell small, 

 whitish, tinted with pink inside and out, 

 especially toward the centers; ends some- 

 what rounded; concentric lines distinct, 

 evenly placed, at anterior end slightly 

 broken by radiating sculpture. Length 

 7 mm. 



PI. 26, Fig. 10 



South Carolina; Florida Keys; West 



Indies 



Family Myidae (from Myax, a Mussel ) 



Hinge with spoon-shaped tooth in 

 one valve and corresponding opening in op- 

 posite valve. Joined by a cartilage. 



GENUS IJYA Linng 1758 

 (SOFT SHELL CLAMS) 



Shell gaping at both ends, erect 

 tooth in left valve. 



MYA ARENARIA Linng. Sand Clam. Shell 

 chalky white; epidermis wrinkled, thin 

 dirty brown; tooth inclined backwards and 

 dovmwards, with oblique ribs in back. Nor- 

 mal length 3.5 inches. 



The soft-shell clam is familiar to 

 everyone residing near the sea. It lives 

 between high-tide and low-tide marks and 

 exposed to the air a portion of the time. 



PI. 26, Fig. 7 



PI. 54, Fig. 3 



Arctic Seas to North Carolina 



MYA TRUNCATA Linne. Short Clam. Shell 

 oblong, rounded at anterior end, truncated 

 at posterior end, widely gaping; color 

 dingy white, covered with a yellowish epi- 

 dermis which extends over edges of the 

 shell. The truncated edges are slightly 

 flaring while the rear of the shell is wide 

 open. Length 2.75 inches. 



The chopped off end is peculiar and 

 readily separates the shell from others. 

 After violent gales it is sometimes thrown 

 upon shores but is most abundant at Georges 

 and the Grand Banks where it is a favorite 

 food of codfish. 



PI. 26, Fig. 8 



Greenland to Massachusetts; Clr- 



cumpolar 



Family Corbulidae 



GENUS CORBULA Brugulere 1797 



(BASKET SHELLS) 



Valves uneqixal, the right often 

 the larger; single large tooth below umbo 

 in right valve, deep pit behind it but no 

 lateral teeth, the pit a repository for 

 tooth of right valve; elevated process in 

 front of pit and sometimes a rudimentary 

 tooth behind it; umbones conspicuous, the 

 one upon the right valve usually the 

 strongest; no pallial sinus. 



