1918] Packard: Molluscan Fauna from San Francisco Bay 247 
three localities, being the most abundant at station D5788. It is 
associated with Nucula tenuis at two of these stations. Dredged in 
depths ranging from 39 to 68 fathoms on bottoms composed of fine 
dark green sand. 
Range.—Bering Sea to San Diego, California (Dall). 
LEDIDAE 
Leda Schumacher 
Leda hamata Carpenter 
Plate 14, figure 5 
Leda hamata Carpenter (1863), p. 644; Arnold, R. (1903), p. 97, pl. 17, 
fig. 4. 
Description.—This species was described by Arnold (1903) as follows: 
‘“Shell small, elongate, trigonal, convex, thin; umbones anterior, turning 
slightly toward the posterior end; short, rounded anteriorly; much lengthened, 
narrowed and abruptly truncated posteriorly; surface sculptured by strong, 
concentric raised lines; a raised band, strongly transversely sculptured by con- 
tinuations of the concentric ridges, passes from the umbo, around the escutcheon, 
to the posterior end; on the interior of the posterior end is an elongated, raised 
process; escutcheon deep-set, smooth.’’ 
Length, 3 to 10 mm. 
Occurrence.—At stations D 5785 (2), D 5789 (4), west of Farallon 
Islands (1). 
This species has been obtained by the Survey at three dredging 
stations outside the Golden Gate. It was taken in depths, ranging 
from 39 to 815 fathoms, on bottoms that are predominately sandy. 
Range.—Puget Sound to Panama (Dall). 
Leda navisa Dall 
Leda navisa Dall (1916b), p. 395. 
Description.—This species is described by Dall as follows: 
““Shell elongate, arcuate, inequilateral, with slender recurved rostrum and 
well-marked smooth impressed escutcheon, but no lunule; base convexly arcuate, 
rostrum obliquely truncate, anterior end evenly rounded; beaks obscure, 5.5 mm. 
from the anterior end; sculpture of numerous sharp concentric low ridges, with 
wider flat interspaces, obsolete toward the rostrum; anterior teeth about twelve, 
posterior about twenty, the resilifer minute, subumbonal, not projecting; in- 
terior chalky, a small medial ridge near the end of the rostrum. Height, 7; 
length, 16; diameter, 5 mm.’’ 
This species was obtained by a previous survey in 191 fathoms of 
water off the Farallon Islands. 
Range.—Known only from the vicinity of the Farallon Islands, 
which is the type locality for the species. 
