3 34 America}! Seashells 



% inch in length, thin, translucent. Periostracum shiny, light-brown, 

 with slender, radial lines of darker brown which are finely striate posteriorly. 

 Ligament bounded by a single, arched prop or rib. Uncommonly dredged 

 offshore. 



Order PROTOBRANCHIA 

 Suborder NUCULACEA 



Key to Families 

 a. Chondrophore below hinge present: 



b. External ligament absent; shell ovate Nuculidae. 



bb. External ligament present; shell elongate .... Nuculanidae. 



aa. Chondrophore absent; shell ovate Malletiidae. 



Family NUCULIDAE 

 Genus Nucula Lamarck 1799 



Shell ovate, usually less than Yz inch in size; interior pearly; ventral mar- 

 gins usually with fine denticulations. 



'"mxmw^" 



■-"'W^ 



Figure 70. Atlantic Coast Nut Clams, a and b, Nucida proxima Say, ^ inch; 



c, N. tenuis Montagu, Yo inch (both coasts); d, N. delphinodonta Mighels, Yiq 



inch; e, N. atacellaim Schenck, Y& inch. 



Subgenus Nucula s. str. 

 Nucula proxima Say 



Nova Scotia to Florida and Texas. 



Atlantic Nut Clam 



Figure 70a, b 



% inch in length, obhquely ovate, smooth. Color greenish gray with 

 microscopic, embedded, axial, gray lines and prominent, irregular, brownish, 

 concentric rings. Outer shell overcast with oily iridescence. Anterior end 

 often with microscopic, axial lines. Ventral edge minutely crenulate. Com- 

 mon just offshore in mud. 



