276 University of California Publications in Zoology. |Vou.5 
In the second place, as is to be shown in the present paper, 
the cowbirds of the Great Basin are subspecifically distinct from 
those of the eastern United States; and, furthermore, their 
closest relationship is with the subspecies occupying the region 
from Arizona and southeastern California southward through 
Mexico ‘‘to Oaxaca, Colima, and Jaliseo’”’ (fide Ridgway, Bds. 
N. & Mid. Am. IT, 1902, 210). It is from this latter form that 
the Great Basin race was probably derived, and not from the 
form east of the Rocky Mountain plateau. 
The present study of the question was stimulated by a series 
of twelve adult cowbirds recently come to hand from a single 
small area in northern Nevada, this being the result of intensive 
field work carried on during the summer of 1909 by Walter P. 
Taylor and Charles H. Richardson, Jr., under the direction of 
Miss Annie M. Alexander. This series, together with the rest of 
the extensive collections obtained during the 1909 expedition to 
Nevada, has been donated by Miss Alexander to the Museum of 
Vertebrate Zoology. 
It is here assumed that the various published records of the 
““cowbird’’ from the Great Basin region of the western United 
States were based upon individuals of the same subspecific 
characters as exhibited by the specimens at hand. It seems that 
extremely few cowbirds have been preserved previously from the 
region, and none of them are available to me. At any rate 
twelve specimens from one locality are preferable, for purposes 
of specific characterization, to twelve specimens from as many 
widely separated localities, even if in the same general area. 
Molothrus ater artemisiae, new subspecies. 
Nevada Cowbird. 
Typr.—Male adult; no. 8825, Univ. Calif. Mus. Vert. Zool. ; 
Quinn River Crossing, Humboldt County, Nevada; May 31, 1909; 
C. HT. Richardson, Jr. 
CHaractrers.—Similar to Molothrus ater ater (Boddaert) of 
the eastern United States, but somewhat larger, with propor- 
tionally longer and more slender bill; similar to M. a. obscwrus 
