53 
638 Ancylus caurinus W. Cooper. 
Living: Black river, Puget Sound, to Sierra Nevada moun- 
tains, Cal. 
Considered by Tryon as identical with A. fragilis. 
639 Ancylus crassus Hald. 
Shell coarse, somewhat ponderous, ovate, elevated; lines of 
growth conspicuous; apex eroded, placed far back; anterior and 
lateral slopes convex, posterior slope steep and rectilinear. Color 
opaque chestnut-brown. Length 8, width 6.25, height 3 mm. 
Living: Oregon (Nuttall). 
640 Ancylus fragilis Tryon. 
Shell very fragile, sides nearly parallel or slightly incurved in 
the middle, diverging anteriorly; ends rounded, apex elevated, 
acute, curved backwards, with about two-thirds of the shell ante- 
rior to it. Length 4, width 1.5, height 1 mm. 
Living: Vallejo and coast region, California. 
641 Ancylus kootaniensis Baird. 
Shell ovate, ashy, concentrically striate, vortex anterior, ob- 
tuse, shining within. Length 9, width 6 mm. 
Living: Kootanie and Spokane rivers, British Columbia. 
642 Ancylus patelloides Lea. 
Shell thick, elliptical, spotted, obliquely conical; strize minute, 
crowded; apex submedial. 
Living: Arroyo San Antonio (Trask); Santa Cruz; Canoe 
creek; San Francisco; upper Sacramento river, Cal. Oregon. 
See Lanx patelloidea. 
643 Anodonta angulata Lea. 
Washingtonia, to Tulare county, Cal. Idaho. Montana. 
644 Anodonta kennerleyi Lea. 
British Columbia, latitude 49 degrees, and north. Lake Chi- 
loniyuck, Washington. 
645 Anomalocardia subimbricata Sowerby. 
West coast, latitude 26 degrees?, to Peru, South America. 
646 Aplysia californica Cooper, Cal ac pr 3:57. 
“Form and external appearance as usual in the genus. Length 
15, breadth 5 inches, height about the same. Color pale gray or 
greenish, becoming purplish on the side, folds of mantle with 
scattered white specks, from which an irregular network of brown 
lines extends over the rest of the body, interspersed with large 
brown blotches. Inner surface of mantle varied with alternating 
painted bars of white and dark brown interlocking together. Sole 
of foot black. Eyes very minute. Shell contained in the sub- 
stance of the mantle caritaginous, translucent, trapezoidal or 
hatchet-shaped, margins rounded, slightly convex above, the nu- 
cleus or center in the old specimens distant from the posterior 
end or apex. Faint radiating lines diverging from the nucleus, 
crossed by an irregular network of darker lines, all ending ab- 
ruptly at some distance from the margin, which has thus a wide, 
nearly transparent border. An accessory plate arises on the inner 
surface from the nucleus, spatulate in form and slightly raised. 
The 2 younger specimens have the clear border and accessory 
plate less developed, and very young ones do not probably show 
these characters at all, but resemble the typical Aplysia in the 
