118 
eon narrow, longer, rather obscure; posterior end of valves round- 
ed, slightly compressed and with a narrow gape when closed; 
hinge resembling that of M. polynyma Stm., but more concen- 
trated, cartlage pit large, rather produced; posterior muscular 
impression larger, pallial sinus rather large, rounded in front. 
There is a faint posterior flexure of the valves and a feeble marked 
area above it, on which the epidermis is more conspicuous. Lon. 
108, alt. 87, diam. 45 mm, in a moderately sized pair, but the 
adult reaches 140 mm. in length.’’—Dall, Nautilus 7:137, t 5 f 3. 
Neeah bay, Wash., to San Diego, Cal. 
Synonymy:—Standella Californica Cpr. (not Conr. or Desb.). 
1626 Mactra Hemphillii Dall. ; ’ 
‘‘Shell large, thin, inflated, subequilateral, creamy white with 
a yellow thin epidermis, which over the body of the shell in young 
shells is beautifully evenly concentrically striated and on the 
posterior dorsal area is irregularly wrinkled, with an elevated 
raphe of epidermis at the margin of the area; beaks rather prom- 
inent, the anterior end of the valves longer than the posterior; 
posterior dorsal slope excavated; lunule obscure, escutcheon 
marked by prominent elevated radial lines of epidermis; the dor- 
sal margin pouting in front of the ligament, the posterior slope 
convex, the posterior flexure faint, but marked by a recession of 
the ventral border of the valves, which gape but very little and 
not at all in front; anterior end rounded, but smaller than the 
posterior; ventral border arcuate; hinge and pallial sinus much 
as in the last species, except that the sinus is somewhat smaller 
and less depressed. Lon. 120, alt. 93, diam. 50 mm.’’—Dall, Nau- 
tilus 7:137 t 5 f 2. Section Standella. 
Type locality:—San Diego, Cal. (Hemphill, Cooper). 
1627 Mactra dolabriformis Conrad, 1867. 
“Shell much compressed, polished white under a dull epider- 
mis, subequilateral with inconspicuous beaks. It closely resem- 
bles M. falcata Gld. (from type) but has higher beaks more cen- 
trally set, the anterior end more attenuated and less truncate, 
the left anterior lateral tooth single and distally more prominent; 
the left cardinal larger and wider; the posterior adductor scar 
horizontally elongate and smaller. Lon. 90, alt. 63, diam. 26 
mm.’’—Dall, Nautilus 7:138 t 5 f 1. 
San Diego, Cal. Guaymas, Son., Panama (Conrad). 
1628 Mactra polynyma Alaskana 
Dall, Nautilus 7:138 suggests this varietal name for the north- 
ern shell generally referred to M. falcata. 
1629 Mulinia modesta Dall, Nautilus 8:5 t1f (lower). 
Type locality:—Guaymas, Son. (Sloat). 
1630 Mulinia coloradoensis Dall, Nautilus 8:6, t 1, upper f. 
Type locality:—Head of the Gulf of Cal. (Edward Palmer). 
1631 Variety acuta Dall. Nautilus 8:6 t 1 left f. 
“With the typical form, common.”’ 
1632 Mulinia Bradleyi Dall, Nautilus 8:6. 
Type locality:—Panama (Bradley). 
1633 Urosalpinx cinereus 
Introduced from the Atlantic into the oyster beds in San 
Francisco bay, Cal. (see Stearns, Nautilus 8:13). 
1634 Helix (Arionta) coloradoensis 
“Shell orbicular, moderately depressed, whorls slightly ele- 
vated, apex obtuse, whorls 4-4 and a half, rounded. Umbilicus 
narrow, showing the penultimate whorl, though partially covered 
by the reflection of the lip at the point of junction with the base 
of the shell. Aperture obliquely ovate, nearly circular, and almost 
as broad as high. Lip slightly thickened and reflected, or sim- 
