CLASS PELECYPODA 
61 
other valve, ears subequal, byssal notch short, acute; one or two faint 
radii on the ear above it. Height, 7; breadth, 7; diameter, 2 mm. (Dali.) 
Type in U. S. N. M., No. 214056. Type locality, off San Diego, 
California, in 822 fathoms. 
Range. Known only from the type locality. 
Pecten davidsoni Dali, 1897. 
The Nautilus, 11:86, Proc. U. S. N. M., 24; pi. 40, figs. 5, 6. 
Shell small, suborbicular, compressed, waxen white, the left valve 
with 21 rounded ribs, surmounted by (when not worn off) continuous 
rows of minute subglobular scales, the interspaces wider, flat and per¬ 
fectly smooth, ears very small, the anterior with five or six imbricated 
radii; sculpture obsolete near the umbones; right valve sculptured with 
faint concentric impressed lines over the whole surface, and distally with 
numerous minute, obsolete, fine, scaly riblets; posterior ear transversely 
striated, very small, anterior one with four or five scaly radii, a well 
marked sinus leaving an imbricated fasciole and no ctenolium. Interior 
polished, the left valve fluted internally in harmony with the external ribs. 
Alt., 14; lat., 14; diameter, 3.5 mm. (Dali.) , 
Type in U. S. N. M. Type locality, Davidson Bank, Alaska, in 280 
fathoms green mud. 
Range. Davidson and Bowers Banks, Bering Sea. 
Pecten incongruus Dali, 1916. 
Proc. U. S. N. M., 52 :403. 
Shell small, white, suborbicular, left valve rather flat with short 
straight hinge line, ears concentrically scaly, sculpture of disk concentric 
continuous low sharp lamellae, crossed by slightly raised radial lines, con¬ 
spicuous only at the intersections which form in the middle of the disk 
square reticulations with a small conspicuous pustule at each intersection; 
laterally these are more crowded; right valve concave near the margin, 
closely regularly concentrically lamellose; anterior ear with five radial 
lines, coarsely lamellose with a shallow notch and serrate margin. Height, 
14; breadth, 15; diameter, 3 mm. (Dali.) 
Type in U. S. N. M., No. 207273. Type locality, Station 2986, 
southwest of San Diego, in 684 fathoms. 
Range. Known only from the type locality. 
Pecten binominatus* Hanna, 1924. 
Set. Res. Can. Ar. Exp., 8. pt. A, 19a, pi. 2, figs. 7, 8. Proc. Cal. Acad. Sci. (4) 13:175. 
Shell suborbicular, translucent white, extremely thin and fragile; 
hinge line straight, the ears subequal, the right anterior ear slightly con- 
* New name for Pecten andersoni Dali, 1919; not P. andersoni Arnold, 1906. 
