NUCULIDAE 3 35 



Nucula atacellana Schenck Cancellate Nut Clam 



Figure yoe 



Massachusetts to Maryland. 



Vs inch in length and oval in outline; the cancellate sculpturing is due 

 to the crossing of numerous radial and concentric threads. Interior scarcely 

 pearly and with a thick, transparent glaze. Color yellowish brown to light- 

 tan. Commonly dredged offshore down to 500 fathoms. Formerly known 

 as N. reticulata Jeffreys and cancellata Jeffreys. 



Nucula crenulata A. Adams Atlantic Crenulate Nut Clam 



South Carolina to Key West, Florida. 



% inch in length, ovate, internal margin finely crenulate. With numer- 

 ous concentric, fine ribs which have numerous microscopic crenulations be- 

 tween them. Interior scarcely pearly; overlaid by a thick, transparent layer 

 of shell matter, through which radial fractures or lines are discernible; color 

 yellowish. Dredged in shallow water. Similar in outline to N. tenuis (see 

 fig. 70c). 



Nucula exigua Sowerby Pacific Crenulate Nut Clam 



Southern California to Ecuador. 



%6 inch in length (5 mm.), shaped hke tenuis and the preceding species. 

 Concentric rings strong with radial crenulations between. Strongly project- 

 ing lunular area just under the beaks. Color yellowish. Dredged in shallow 

 water. Very similar to N. crenulata from the Western Atlantic. 



Nucula delphinodonta Mighels Delphinula Nut Clam 



Figure jod 



Nova Scotia to Maryland. 



Vie inch (3 mm.) in length, ovate, fat and smooth except for coarse 

 concentric growth lines. Anterior end slightly pushed in under beaks and 

 bordered by slight carination. Ventral edge smooth. Color olive-brown. 

 9 teeth posterior to and 4 teeth anterior to chondrophore. 



Nucula tenuis Montagu Smooth Nut Clam 



Figure 70c 



Labrador to Maryland. Alaska to Lower California. 



Usually %6 inch in length (up to % inch in Alaska), ovate, smooth 

 except for irregular growth lines. Color a shiny olive-green, sometimes with 

 darker lines of growth. No radial lines. Ventral edge smooth. 



