52 



629 Amphissa bicolor Dall. 



"Shell small, solid, pale with brownish bands and 6 convex 

 whorls; nucleus eroded in the specimens; suture distinct, not 

 appressed, whorls full, with 11-13 narrow rounded ribs extending 

 nearly from suture to suture; spiral sculpture of numerous flat- 

 tened strap-like cinguli separated by subequal channeled shallow 

 interspaces; epidermis thin and yellowish; color of shell pale 

 straw color with a brownish base and a brown band extending 

 from the periphery half-way back to the suture; aperture about 

 equal to the spire, the penultimate rib behind it a little swollen; 

 pillar slender, polished white with little callus; canal wide, short, 

 recurved; outer lip simple, slightly reflected; not lirate inside. 

 Longitude of shell, 14; of aperture, 7.7; maximum diameter of 

 shell, 8 mm. Habitat: Dredged by the U. S. Fish Commission at 

 various places off the coast from Point Sur to San Diego, and in 

 the Santa Barbara channel in depths varying from 124 fathoms at 

 the south to 298 fathoms at the north, over a sandy or muddy 

 bottom. The operculum is brownish and resembles that of A. 

 vesicolor Dall. The brown coloration, though generally disposed 

 in bands as described, is variable, and occasionally appears in a 

 zigzag pattern on the pale ground, or generally suffused over the 

 surface, or even maculated, as in Nitidella. The apex when per- 

 fect is probably moderately acute, but is more or less eroded on 

 all the specimens." — Dall, U. S. Nat Mu s pr 15:213, t 20, f Ag 

 1892. 



630 Amnicola micrococcus Pilsbry. 



Oasis Nye co., Nevada. Death Valley, Inyo co., Cal. 



631 Ammrola protea Gould. 



Melania exigua Conrad. Phila ac pr 7:269 (F 1855): — "Tur- 

 reted; volutions 8, disposed to be angulate and somewhat scalari- 

 form above; cancellated, longitudinal lines wanting on the lower 

 half of the body whorl; columella reflected; aperture elliptical. 

 Length, one-iiftb of an inch. Colorado desert, California (Or Le 

 Conte). The specimens are numerous and of a chalky whiteness, 

 showing that they are all dead shells." 



Living: Dos Palmas spring, Colorado desert, near Salton (Or- 

 cutt). Arizona. 



Quaternary: Colorado desert (Orcutt). 



The most numerous of all the fossil shells found on the desert, 

 and though one of the smallest species, its numbers are so great 

 as to exceed the others in bulk as well. 



632 Amnicola turbiniformis Tryon. 



Snake river, Idaho, to Truckee river, California. 



633 Amphisphyra subquadrdata Carpenter. 

 California. 



634 Amphissa undata Carpenter. 

 Catalina Island, California. 



635 Amphithalamus lacunatus Carpenter. 

 San Pedro and San Diego, Cal. 



636 Anachis coronata Sowerby. 



Cedros Island, Lower California, to Panama. 



637 Anachis subturrita Carpenter. 

 San Diego, Cal. 



Synonym of Columbella subturrita. 



