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 Calif ornica 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, 18 67. 



"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 t 1 f (lower). 

 Type locality: — Guaymas, Son. (Sloat). 



1630 Mulinia eoloradoensis 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 Urosalplnx cinereus 



Introduced from the Atlantic into the oyster beds in San 

 Francisco bay, Cal. (see Stearns, Nautilus 8:13). 



1634 Helix (Arionta) eoloradoensis 



"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- 



