166 
2418 Zirfoea gabbi Tryon. 
Chace, Nautilus 28:144, note on occurrence in Anaheim bay, 
Cal. 
2419 Lowe, Herbert N.: 
Notes on the mollusk fauna of San Nicholas Island. Nautilus. 
17:66. 
2420 Acmea gigantea Gray. 
Recorded in above list. 
2421 £=Sonorella walcottiana 
Bartsch, Wash. Biol. soc. pr 16:103-104. 
Type locality: —Palm Springs, Riverside Co., Cal. 
2422 Schismope rimuloides Cpr. 
Pilsbry, Nautilus 17:84, records from San Diego, Cal. (Hemp- 
hill). 
Originally published as Scissurella, from Mazatlan. 
2423 =«=‘Trivia ritteri Raymond. 
“Shell small, white, form ovate, inflated, anterior extremity 
slightly produced, spire completely covered, but rather promi- 
nent, base convex, outer lip margined, strongly sculptured with 
about 20, smooth, sharp ribs, much narrower than the interspaces 
which are nearly flat and scarcely roughened by irregular ruge 
parallel to the axis of the shell, no sulcus, the ribs continuing un- 
changed in width across the back, except that occasionally a few 
ribs near the spire are interrupted at the median line; a few short 
intercalary ribs are usually present on the sides of the shell; aper- 
ture rather wide, armed with 17 to 18 denticulations on the outer 
lip, and 14 to 16 on the inner. Two extreme specimens in size 
measure: length 11:5, breadth 8.6, height 7.2 mm; length 8.2, 
breadth 6.5, height 5.7 mm.’’—Raymond, Nautilus 17:85. 
Catalina Island, in 60 fms.—Monterey (Dall).—Off San Pedro, 
Cal., in 50 fms. Named in honor of William E. Ritter. 
2424 Periploma sulcata 
“Shell rotund, white, with the left valve flatter, thin, sculp- 
tured with numerous, close-set, irregularly concentric, more or 
less interrupted, low ridges, separated by subequal shallow inter- 
spaces, the surface is also microscopically shagreened, and there 
is a low rib extending from the beak to the lower margin of the 
ill-defined rostrum and an ill-defined furrow radiating from the 
beak toward the anterior base, in the right valve; beaks low, dis- 
tinctly fissured; anterior dorsal hinge line rounded, posterior 
ditto, shorter, nearly rectilinear, forming with the elevated rib a 
subtriangular space which is free from the undulations which 
cover the rest of the shell; interior shining, hardly nacreous, the 
muscular impressions very small, the pallial line obscure; chon- 
drophores prominent, spoon-shaped, extending obliquely forward, 
and with their connecting resilium sustaining a proportionately 
large triangular lithodesma; the chondrophores are supported be- 
hind by well-developed clavicular props, which are inserted pos- 
teriorly on the surface of the valve below the linear hingeline. 
Length 32, height 27, diam. of right valve 6 and of the left valve 
4 mm.’’—Dall, Nautilus 17:122. 
Type locality:—San Pedro, Cal. (Mrs. T. S. Oldroyd). 
2425 Dentalium vallicolens 
“Adult shell large, rather slender, moderately curved poste-- 
