18 ilOLLUSKS FBOM WEST COAST OF AMERICA— BALL. vol.xviii 



slightly radially striate, margins flattish, smootb; anterior adductor 

 scar narrow, posterior wider, tlie pallial line joining it in front of its 

 posterior edge, producing an indentation, though not a sinus, of the 

 pallial line; hinge narrow; teeth small, compressed, three (more or less 

 obscure) in each valve; in the right a long, strong anterior lamella, 

 extending most of the way between the umbo and the adductor scar, 

 with a socket around its posterior end, above this a short, small, thin 

 lamina, joined around the socket with a thicker lamina, obscurely wavy 

 and extended backward ; in the left valve a stout subtriangular central, 

 joined to a thin, short, anterior lamina, with a socket under it; a short, 

 obscure, radial tooth behind the central one; no lateral teeth in either 

 valve, and the cardinals, as usual in this group, somewhat variable, 

 obscure, or ill-defined. Height of shell, 40; length, 58; diameter, 23 

 mm,; the vertical of the beaks, 17 mm. behind the anterior end of the 

 shell. 



Type. — No. 12G751, U. S. N. M., from U. S. Fish Commission station 

 3009, in the Gulf of California, off Concepcion Bay, in 857 fathoms, mud ; 

 temperature, 38° F. Also specimens (No. 106857, U. S. N. M.) from 

 station 3340, oft" Tillamook, Oregon, in 780 fathoms. 



This large, rather compressed species has somewhat the outline of 

 the Indo-Pacific Tapes. 



CALLOCARDIA OVALIS, new species. 



Shell resembling the last species, but smaller, more oval, the poste- 

 rior dorsal border more arched, the proportional inflation greater, the 

 lunule wider, the ligament proportionally and actually longer, the epi- 

 dermis more adherent and without projecting fringes or lamelhe; inter- 

 nally the teeth are smaller and more feeble, and the pallial line recedes 

 less at the posterior adductor scar. Height, 26; length, 30; diameter, 

 10 mm.; the vertical of the beaks 8 mm. behind the anterior end of 

 the shell. 



' U. S. Fish Commission station 3360, in the Gulf of Panama, in 1,072 

 fathoms, sand; temperature, 36.4° F. 



Type.—^o. 106898, U. S. N. M. 



CALLOCARDIA GIGAS, new species. 



Shell large, rather thin, inflated, with a thin, wrinkled, olivaceous 

 epidermis over an earthy, concentrically, irregularly striated surface; 

 beaks low, inconspicuous; lunule and escutcheon somewhat impressed, 

 but not limited by any distinct line; valves elongated, recalling the 

 shape of Modiola capax, Conrad, in a general way; the anterior side 

 shorter and less high, the base impressed in the middle, more expanded 

 in front and behind; dorsal margin rather evenly arched; both ends 

 rounded; internally dentition strong, like that of G. lejyfa, but more 

 distinctly developed; ligament short (about 20 mm.), set in a groove; 

 interior of valve somewhat radially striate; posterior adductor scar 



