206 NEW-YORK FAUNA — MOLLUSCA. 



Cardium ISLANDICUM. 



PLATE XXIII. FIG. 252. Young. 



Cardium islandicum. Linn. Syst. Nat. p. 1124. 



C. pubescens. CoutHouv, Bost. Jour. Vol. 2, p. 60, pi. 3, fig. 6 (young). 



C. islandicum* Gould, Invertebrata of Massachusetts, p. 89, fig. 58. 



Description. Shell large and rather thin, rounded, inflated, nearly equilateral. Beaks pro- 

 minent, incurved, contiguous : anterior dorsal area feebly impressed, subcordate. Surface 

 with thirty-six to thirty-eight sharp ribs, which are covered with a stiff fringe-like epidermis 

 in the young shells. Margin of the shell crenate internally, and the surface impressed by 

 the ribs. 



Color. Epidermis dull yellowish brown ; within, straw-colored, or brilliant yellow in the 

 young. 



Length, 1-0-2-5. Width, 0-9-2-3. Diameter, 0-9-1-0. 



This shell occurs from Cape Cod, near which it is obtained plentifully from the stomachs 

 of fishes, along the coast of Maine, where it is found on the shores, to the Arctic circle, and 

 on both sides of the Atlantic. 



Cardium grcenlandicum. 



PLATE XXIII. FIG. 250. 



(STATE COLLECTION.) 



Cardium gramlandicum. Gmelin, Syst. Nat. p. 3232. 



Aphrodita columba. Lea, Trans. Am. Phil. Soc. Vol. 5, p. 110, pi. 18, fig. 54i 



Cardium grcenlandicum. Gould, Invertebrata of Mass. p. 92. 



Description. Shell large ; the adult very thick and robust, heart-shaped, somewhat com- 

 pressed. Beaks submedial, prominent, incurved, contiguous. Surface with concentric in- 

 cremental lines, crossed by numerous almost obsolete elevated radiating lines. Hinge liga- 

 ment small : margin entire, gaping behind. Cardinal teeth almost obsolete ; lateral teeth 

 small and distinct. 



Color. Epidermis thin, pale olivaceous or drab : the young with occasionally zigzag darker 

 lines ; beneath this, dingy white. Interior opake white, flesh or salmon-colored. 



Length, 1-5-2-3. Width, 1 -6 - 2-7. Diameter, 1 -3. 



This shell has not yet been found south of the shores of Maine, except in the stomachs of 

 fishes. It has much the external configuration of a Mactra, for which it has been mistaken ; 

 and the occasional absence of the cardinal teeth has led Mr. Lea to arrange it under a new 

 genus. 



