416 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY. 
them under the former name, while the genus of Veneridae was relegated to its 
proper family. 
The shells of this family appear to be rather characteristic of the abysses, but 
unfortunately very few specimens of the larger forms have yet been obtained in 
the living state, and it is not yet certain that all the species belong to a single genus. 
In the typical forms the pallial line, while entire, joins the posterior adductor 
scar proximally, so that there is a small triangular space below the scar which in 
most unsinuate bivalves would have been included in the area surrounded by the 
pallial line. 
Vesicomya lepta Datt. 
Plate 18, figures 13, 14. 
Callocardia lepta Dall, Proc. U.S. Nat. Mus., 1896, 18, p. 17. 
Shell large, thin, earthy, white, compressed, with an olivaceous or yellowish, 
dehiscent epidermis, with concentric wrinkles and projecting laminae, which in 
the young are somewhat regularly spaced and distant, in the adult crowded and 
irregular; beaks small, low, not conspicuous, moderately inflated; valves evenly 
arcuate below, rounded at both extremities, the anterior shorter and less high 
than the posterior; lunule narrow, long, bounded by an incised line; ligament 
external, long, set in a groove, with the escutcheon narrow, its edges elevated 
above the dorsal margins of the valves and obtusely keeled, extending backward 
one half longer than the length of the ligament; interior smooth, or slightly 
radially striate, margins flattish, smooth; anterior adductor scar narrow, posterior 
wider, the pallial line joining it in front of its posterior edge, producing an in- 
dentation, though not a sinus, of the pallial lme; hinge narrow; teeth small, com- 
pressed, 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; diam. 23 mm.; the vertical of the beaks 17 mm. behind the anterior end 
of the shell. 
U. 5. 8. “ Albatross,” station 3009, in the Gulf of California, off Concepcion 
Bay, in 857 fathoms, mud, temperature 38° F. U.S. N. Mus. 126,751. Also 
specimens from station 3346, off Tillamook, Oregon, in 786 fathoms, mud, temper- 
ature 37°.3 F. 
This large, rather compressed species has somewhat the outline of the Indo- 
Pacific Paphia. The specimen figured was immature, but the magnified figure 
exactly represents the larger adult shell. 
