NUCULANIDAE 3 39 



About H to % inch in length, shiny green-brown, with prominent con- 

 centric sculpture and characterized by the nearly central umbones. Rostrum 

 bluntly pointed, slightly upturned at the end. Concentric ribs disappear just 

 anterior to the carinate border of the dorsal area which is strongly wrinkled. 

 Adults over K' inch become quite fat. Commonly dredged off southern Cali- 

 fornia in shallow water. Sorensen reports that this species is found com- 

 monly in fish stomachs off Monterey. 



Nuculana penderi Dall and Bartsch Pender's Nut Clam 



Forrester Island, Alaska, to Santa Barbara, California. 



/4 to % inch in length, moderately elongate, very fat; rostrum short 

 and pointed; concentric ribs prominent and evenly developed. Dorsal area 

 of rostrum oval, finely ribbed and bounded by a sharp, smooth, large rib. 

 Periostracum light-brown. Moderately common offshore. 



Nuculana hindsi Hanley Hinds' Nut Clam 



Nazan Bay, Alaska, to Costa Rica. 



% inch in length, moderately elongate (example: 7.8 mm. long; 4.4 

 mm. high; both valves 3.0 mm. wide); posterior end rostrate, slightly turned 

 up at the end. Dorsal area of rostrum smoothish except for faint axial threads 

 bounded by smooth carinate rib. Sculpture of evenly sized, closely spaced, 

 distinct, concentric ribs which become obsolete just before the rostral rib. 

 Exterior light yellowish brown. Interior white with faint pearly sheen. N. 

 acuta Conrad, a name often given to this Pacific Coast species, has its rostral 

 rib crossed by concentric ribs. N. penderi Dall and Bartsch is twice as fat, 

 with a very ovate lunule and is more rounded at the ventral margin. Hanley 

 in i860 first reported this species from "Gulf of Nicoya, Costa Rica." This 

 is probably "N. re don do en sis''"' "Burch" \\'oodring 1951. It is dredged com- 

 monly off the West Coast from 1 5 to 600 fathoms. 



Subgenus Thestyleda Iredale 1929 

 Nuculana hamata Carpenter Hamate Nut Clam 



Figure z6A 



Puget Sound to Panama City, California. 



Under % inch in length, moderately compressed, exterior with strong 

 concentric ribs; characterized by the squarely truncated posterior end of the 

 long rostrum. Fairly commonly dredged off Calif ornian shores from 20 to 

 200 fathoms. 



