378 American Se ash ells 



shell. Occasionally the ribs are less strongly developed. Common from just 

 offshore to 30 fathoms. 



Superfajnily CARDITACEA 



Family CARDITIDAE 



Genus Cardita Bruguiere, 1792 



Shell small, thick, radially ribbed, quadrate, with a slight ventral gape 

 and having a byssus. The animal has a marsupium to contain its eggs. Pos- 

 terior right cardinal usually absent or almost so. This appears to be the 

 accepted use of Cardita according to Winckworth, Chavan, Lamy and Dall. 



Subgenus Carditamera Conrad 1838 



Carditaviera has shells which are more elongate and have strong lateral 

 teeth. 



Cardita floridana Conrad Broad-ribbed Cardita 



Plate 30a 



Southern half of Florida and Mexico. 



I to I /4 inches in length, about half as high, elongate, inflated, solid and 

 heavy. Surface with about 20 strong, rounded, raised, beaded, radial ribs. 

 In live material, the gray periostracum obscures the color of the shell. Ex- 

 terior whitish to gray with small bars of chestnut color on the ribs arranged 

 in concentric series. Interior white with a small light-brown patch above 

 the two muscle scars. Beaks close together. Lunule small, very deeply in- 

 dented under the beaks. Ligament moderately large, visible from the out- 

 side. Very common on the west coast of Florida where it is washed ashore. 

 Used extensively in the jewelry business. 



Cardita gracilis Shuttleworth is doubtfully recorded from Florida but is 

 known from Mexico to Puerto Rico. It is quite elongate, narrow at the 

 anterior end, with larger, smoothish ribs, and the posterior lateral tooth is 

 stained dark-brown. Uncommon. 



The Pacific Coast species is Cardita carpenteri Lamy (pi. 29r) which is 

 V'z inch long and ranges from British Columbia to Lower California in shal- 

 low to deep water. Its color is brownish gray with a purplish interior. 



Subgenus GJaiis Miihlf eld 1 8 1 1 

 Cardita dominguensis Orbigny Domingo Cardita 



North Carolina to southeastern Florida. 



% inch in length, ovate, inflated; beaks close together, pointing toward 



