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 Dall. 



Plate 18, figures 13, 14. 



Cdlocardia 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 coucentric wrinkles and projecting laminae, which in 

 the youug 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, produting an in- 

 dentation, though not a sinus, of the pallial line ; 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 tliin, 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 sholl, 40 ; length, 

 58; diani. 23 mm.; the vertical of the beaks 17 mm. behind the anterior cud 

 of the shell. 



U. S. S. "Albatross," station 3009, in the Gulf of California, off Conccpcion 

 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. 



Tliis large, rattier compressed species has somewhat the outline of the ludo- 

 Pacific I'aphia. The specimen figured was immature, but the magnified figure 

 exactly represents the larger adult shell. 



