PERIPLOA4A TIDAE 47 3 



in a ventral direction. Sculpture of irregular, fine, concentric growth lines. 

 A weak radial groove runs from the beak to the anterior part of the ventral 

 edge. Moderately common in dredge hauls from i to 200 fathoms. P. papy- 

 raceiim is an incorrect spelling for this species. 



Feriploma -fragile Totten, the Fragile Spoon Clam (Labrador to New 

 Jersey, 4 to 40 fathoms), differs in being more rostrate anteriorly, the beaks 

 pointing more forward and placed more anteriorly. Its chondrophore is 

 more horizontal to the hinge line. 



Periplo77ia ineqiiale C. B. Adams Unequal Spoon Clam 



Plate 28X 

 South Carolina to Florida and to Texas. 



% to I inch in length, oblong, the left valve more inflated and slightly 

 overlapping the right valve. Fragile and pure white. Beaks close together, 

 each with a short, radial break or slit in the surface. An oblique, low keel 

 runs from the beaks to the anterior ventral margin of the valve. The keel 

 is bounded posteriorly by a groove. Sculpture consists of microscopic, con- 

 centric scratches. Hinge with a single, large, spoon-shaped tooth or chondro- 

 phore, above which is a deep slit where the small, free, triangular lithodesma 

 fits. This species is especially abundant along certain Texas beaches. P. 

 maeqiiivahis Schumacher from the West Indies has not been found in the 

 United States, despite several erroneous records. 



Periplo777a plmihiscuJum Sowerby Common Western Spoon Clam 



Plate 3 IX 



Point Conception, California, to Peru. 



I to 1% inches in length, ovate, thin, with weak, concentric hnes of 

 growth. Right valve fatter than the left; chondrophore ovate-trigonal, its 

 longer diameter directed forward and reinforced posteriorly by an elongate, 

 rib-like buttress. Commonly washed ashore on southern Californian beaches. 



Periplovta discus Stearns Round Spoon Clam 



Figures 97a; 28I 



Monterey, California, to La Paz, Lower California. 



I to I /4 inches in length, similar to plajmisaihwi, but almost circular in 

 outline, except that the posterior end is slightly lengthened into a short, broad, 

 blunt rostrum. Uncommonly dredged in mud bottom at several fathoms; 

 rarely washed ashore after storms. 



