28 
MARINE SHELLS OF WEST COAST OF NORTH AMERICA 
Yoldia secunda Dali, 1916. 
Proc. U. S. N. M., 52:398. 
Shell large, thin, inequilateral, inflated, subtruncated and recurved 
behind; color of a light grayish olive, more or less disposed in zones; this 
shell much resembles Y. thraciceformis Storer, though it does not attain 
so great a size; it differs by the absence of the oblique elevated posterior 
ray from the umbones, in being more attenuated behind, and in general 
more cylindrically inflated; the hinges hardly gape in front, and less behind 
than in that species; the hinge teeth are more numerous and smaller than 
in thraciceformis of the same length. There are 24 anterior and 20 posterior 
teeth, the resilifer is similar to but smaller than in the species referred 
to above, which has 20 anterior and 10 posterior teeth in a valve of the 
same length. Length, 39; height, 22; diameter, 14 mm, (Dali) 
Type in U. S. N. M., No. 107688. Type locality, Station 3077, in 
Clarence Strait, Alaska, in 322 fathoms. 
Range. Southeastern Alaska, in deep water. 
Yoldia beringiana Dali, 1916. 
Plate 5, fig. 4. 
Proc. U. S. N. M., 52:399. 
Shell large, thin, smooth, except for lines of growth, brilliantly 
polished, inequilateral, hardly rostrate, rounded at each end, less com¬ 
pressed behind than Y. secunda; color a rich yellowish brown, slightly 
olivaceous near the umbones; valves closing completely; escutcheon 
striated, narrower than in secunda; beaks very low, 24 anterior and 17 
posterior teeth, the resilifer ample, cup-shaped, projecting. The pallial 
sinus is rather large and rounded. Length, 40; height, 22; diameter, 16 
mm. (Dali.) 
Type in U. S. N. M., No. 226159. Type locality, Station 3607, 
Bering Sea, off Pribiloff Islands in 987 fathoms. 
Range. Known only from the type locality. 
Yoldia montereyensis Dali, 1893. 
Plate 28, fig. 4. 
The Nautilus, 7, No. 3:29. Nat. Hist. Soc. Brit. Columbia, Bull. No. 2; pi. 2, fig. 16. 
Shell large, stout, inflated, with a polished, dark greenish olive 
epidermis; beaks eroded in all the specimens, situated in the anterior part 
of the middle third of the shell, not prominent; valves full and rounded, 
anterior end evenly rounded into the upper and basal margins; posterior 
end narrower, rounded, the extreme end nearer the cardinal margin with 
which it almost forms an angle, below sloping obliquely toward the basal 
margin, with a very obscure broad ray impressed in a radiating manner 
from the beaks toward the oblique slope, the profile of which it does not 
