376 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
glassy prodissoconch; lunular depression striated, lanceolate, not circumscribed ; 
escutcheon long, lanceolate, striated, the valve margins a little elevated, the area 
strongly impressed, bounded on each side by two flattened rays, separated by 
a feeble depression, extending from the beaks to the end of the rostrum, and 
crossed by a series of small, distant, evenly equally spaced, elevated lamellae; 
body of the shell swollen, the rostrum compressed; anterior end very short; 
sculpture of concentric, narrow, rounded ridges with wider channelled interspaces, 
about twenty-five between the beaks and the base; general form as figured. Lon. of 
shell, 8.5; of beaks behind the anterior end, 2.5; alt. 4.0; diam. 2.5 mm. 
U. S. S. “Albatross,” station 3354, Gulf of Panama, in 322 fathoms, mud, 
bottom temperature 46° F. U.S. N. Mus. 122,915. Also at station 2792, off 
Manta, Ecuador, in 401 fathoms, mud, temperature 42°.9. 
There are fourteen anterior and about nineteen posterior very small and close-set 
teeth on the hinge line, the two series separated by a very small and inconspicuous 
chondrophore. The interior is brilliantly glossy, translucent, and with a low 
longitudinal ridge dividing the channel of the rostrum. The most nearly related 
species, from which this is sufficiently distinct, is Leda hamata Carpenter, of the 
coast of California. 
Leda (Leda) loshka Da tt, n. sp. 
Plate 17, figure 2. 
Shell thin, olivaceous, paler toward the umbones, very inequilateral, polished, 
the disk oval, the posterior end produced in a long rostrum; beaks low, the pro- 
dissoconch not differentiated ; lunule impressed, very narrow, lanceolate, bounded 
by a low but sharp carina; escutcheon narrow, impressed, striated, very long, 
extending from the beaks to the end of the rostrum, the valve margins more 
or less prominent; the area is bounded by two obscure flattish ribs, the lower 
wider, separated by a narrow furrow and extended to the end of the rostrum ; 
disk apparently smooth, but under a lens showing fine concentric and a few 
irregular faint radial striations; dorsum and base gradually attenuated, the ros- 
trum not separated by any marked constriction near its origin; interior glassy, 
the rostrum with an internal keel corresponding to the external furrow; resilium 
very small, wholly internal, obliquely directed backward; hinge with about fifteen 
anterior and twenty-two posterior very small, short, angularly folded teeth. Lon. of 
shell, 16.2; of beaks behind anterior end, 5.0; alt. 6.5; diam. 3.0 mm. The 
teeth were counted on a valve 13 mm. long. 
U.S. S. “ Albatross,” station 3392, Gulf of Panama, in 1270 fathoms, hard 
bottom, temperature 36°.4 F. U.S. N. Mus. 122,916. 
The most nearly related species is Leda cestrota Dall, from the Atlantic, which 
is a mucn larger form with a recurved rostrum. 
Leda (Leda) rhytida Datt, n. sp. 
Shell small, elongate-ovate, slightly inequilateral, translucent white, covered 
with a pale olive-gray periostracum; beaks low, adjacent, lunule and escutcheon 
