SOLEMYACIDAE 33 3 



Order PALAEOCONCHA 



Family SOLEMYACIDAE 



Genus Solemya Lamarck 1818 



The Awning Clams are very primitive in their characters and they have 

 no near relatives. Their shells are fragile, with a weak, toothless hinge, 

 gaping at both ends, and covered by a polished, horny, brown periostracum 

 which extends well beyond the margins of the valves. 



Subgenus Petrasma Dall 1908 

 Solemya velum Say Common Atlantic Awning Clam 



Plate 27a 



Nova Scotia to Florida. 



% to I inch in length, very fragile, and with a delicate, shiny, brown 

 periostracum covering the entire shell and extending beyond the edges. Light 

 radial bands of yellowish brown are present in some specimens. Chondro- 

 phore supported by 2 curved arms. Commonly dredged in shallow water in 

 mud bottom. Compare Florida specimens with occidentalis. 



Solemya bore alls Totten Boreal Awning Clam 



Nova Scotia to Connecticut. 



2 to 3 inches in length, very similar to velum, but more compressed, 

 heavier, and colored grayish blue or lead on the inside of the valves (instead 

 of purplish white). The striking difference is in the siphonal opening of the 

 animal. In velum, there are 2 small, median, low tubercles above the opening 

 and 5 or 6 pairs of short tentacles at the lower end of the opening. In bo- 

 realis, there are 3 pairs (one of which is large and long) of tentacles above 

 the opening and about 1 5 smaller ones bordering the lower half. S. borealis 

 is moderately common offshore. 



Solemya occidentalis Deshayes West Indian Awning Clam 



West coast of Florida and the West Indies. 



^ inch in length, similar to S. velum, but much smaller, and has only 

 one slender ridge or rib bordering the chondrophore. Uncommon just off- 

 shore. Described first by Deshayes in 1857, later by Fischer in 1858. 



Solemya valvidus Carpenter Pacific Awning Clam 



San Pedro, California, to the Gulf of California. 



