~~ 
10 VITRINA PELLUCIDA. 
Monst. sinistrorsum Cockerell, Science’Gossip, 1897, p. 262. 
SHELL with coiling reversed or sinistral. 
Switzerland—Dr. Brot records the finding of a sinistral specimen near Geneva 
(Proc.-Verb. Mal. Soc. Belg., April 1877). 
V. pellucida alaskana Dall, Land & Freshw. Moll. Alaska, 1905, p. 35. 
Vitrina pfeiffert Newcomb, Proc. Cal. Acad. Sci., 1861, ii., p. 92. 
Vitrina alaskana Dall, op. cit. 
QM" Vitrina alaskana Dall, the West American form of the species, 
the name of the author, Dr. W. H. Dall, of the National Museum, 
Washington, D.C., is here associated in appreciative recognition 
of the many elaborate and priceless contributions to conchology from his 
pen, more especially those in elucidation of the phylogeny and other of the 
more profoundly interesting departments of the study. 
SHELL translucent with a marked greenish 
tinge, and is larger and flatter, while the size 
of the whorls increases more rapidly than the 
eastern form V. pellucida limpida. 
BD [hel A 
Fic. 14. BiG. Ld; 
Fic. 14.—V’. alaskana Dall (after W. G. Binney). 
Fic. 15.—Median, admedian, and marginal teeth of 
V. alaskana, highly magnified (after W. G. Binney). 
Prof. Cockerell describes the ANIMAL of a 
Colorado specimen as possessing the head 
and tentacles of a dark purplish-grey ; foot 
greyish-white ; mantle dark grey, minutely 
speckled with whitish. 
The LINGUAL MEMBRANE is described by 
Binney as having a formula of 50+ 1+ 50 
with ten perfect laterals on each side. 
This is the species or race which prevails 
over the western coast of North America, and 
is the most common shell on the islands of 
the Behring Sea and on the continent near 
the sea in Alaska, being often found by the 
sea-beach under drift-wood. In its southern 
range it is absent from the warm lowlands, 
t chiefly affecting lofty altitudes and reaching 
\ —=7 4, height of 10,500 feet in the Sierra and 
Se ie a ee Rocky Mountain ranges ; while northwards 
it extends to Vancouver, the Alaskan Penin- 
sula, the Aleutian and Shumagin Islands, and also as far as the Pribiloff Islands 
in the Behring Sea. 
NEARCTIC DISTRIBUTION. 
New Mexico—Fort Wingate (Binney, Manual, 1885, p. 88); Jemez Sulphur 
Springs ; Clouderoft, and among dead leaves by Pecos River at Vallé Ranch, Nov. 
1902, T. D. A. Cockerell. 
Colorado —Found throughout the state, and recorded from or found at Brecken- 
ridge by H. Prime ; common among the Beaver dams, Empire, by J. D. Putman ; 
head of Gunnison River, by W. G. Binney ; Boulder, by Prof. Cockerell; and White 
Earth River, by Ingersoll; also at Dillon, Summit Co. ; Swift Creek, Custer Co. ; 
Grand Mesa: also near Mam Mountains; and at roots of Hqguisetum, Buzzard 
Creek, Mesa Co. ; Cottonwood Gulch, Saguache Co. ; west fork of Surface Creek, 
Delta Co. ; east fork of Arkansas River, Lake Co.; near Cattle Creek, Garfield Co. ; 
and Routt Co., by Prof. Cockerell ; as well as Howardsville, St. Juan Co., by E. 
Ingersoll. ; 
Utah—City Creek Canon (Call, Bull. U.S. Geol. Surv., 1881, p. 25). St. George 
(Binney, Manual, 1885, p. 88). 
