CARDIIDAE 397 



a single specimen, is much more oblique in shape, resembling the equally rare 

 Erycina jernmidina Dall from off Florida. 



My sella tu77tida Carpenter Fat Pacific Lepton 



Figure Sob 



Alaska to Lower California. 



Vq to %6 of an inch in length, moderately compressed, somewhat tri- 

 angular in shape. The tiny beaks are almost at the very posterior end. Shell 

 dull-white, but commonly covered with a light-brown, smoothish periostra- 

 cum which is faintly marked with concentric, microscopic wrinkles. The 

 hinge teeth are large in comparison to those in other species. Common from 

 low water to 99 fathoms. Has been found in duck stomachs. 



Superfamily CARDIACEA 



Family CARDIIDAE 



Subfamily TRACHYCARDIINAE 



Genus Trachycardium Morch 1853 



Trachycardium muricatum Linne Yellow Cockle 



Plate 39P 



North Carolina to Florida, Texas and the West Indies. 



2 inches in height, subcircular, with 30 to 40 moderately scaled, radiating 

 ribs. Externally light-cream with irregular patches of brownish red or shades 

 of yellow. Interior commonly white, rarely yellow-tinted especially in Flor- 

 ida. A very common, shallow-water species. Compare with eginontianum 

 and magnum which are both more elongate. 



Trachycardium egmontianum Shuttle worth Prickly Cockle 



Plate 39-0 



North Carolina to south Florida and the West Indies. 



2 inches in height, with 27 to 31 strong, prickly, radial ribs. Externally 

 whitish to tawny-gray with odd patches of weak yellow, brown or dull- 

 purple. Interior glossy, commonly brightly hued with salmon, reddish and 

 purple. Do not confuse with muricatum which is more oval, has more ribs 

 which are not sharply scaled at the center of the shell and is commonly only 

 yellowish inside. A common shallow-water species, especially on the Gulf 

 side of Florida. 



Trachycardium isocardia Linne from the West Indies has larger and 

 slightly different scales, 32 to 37 ribs and has not been recorded from Florida. 



Trachycardium magnum Linne Magnum Cockle 



Lower Florida Keys and the West Indies. 



