Sci., 19:42,
May 25, 1940.

_Marginal records_ (Nelson, 1909:82, unless otherwise
noted).--British Columbia: Fairview, Okanagan Valley. Idaho:
Rathdrum Prairie (Rust, 1946:322); Lemhi River; Teton Basin.
Wyoming: Hamsfork; Henrys Fork. Colorado: Hot Sulphur Springs; Mt.
Baldy; Crested Butte; Mill City. Utah: Kanab. Nevada (Hall,
1946:600): Hamilton; Desatoya Mts.; Santa Rosa Mts. California:
Parker Creek, 6300 ft., Warner Mts. Nevada (Hall, 1946:600): 8600
ft., 3 mi. S Mt. Rose; 8900 ft., Lapon Canyon, Mt. Grant; Mt.
Magruder. California (Orr, 1940:43): Tuolumne Meadows; Woodfords;
Tahoe City; 4700 ft., Steele Meadows. Oregon: Antelope. Washington:
Manson (Dalquest, 1948:382).

=Lepus californicus=

Black-tailed Jack Rabbit

Total length, 465-630; tail, 50-112; hind foot, 112-145; ear from notch
(dry), 99-131. Upper parts gray to blackish; tail with black mid-dorsal
stripe extending onto back; never all white in winter. On the tableland
of Mexico and in the southwestern United States where this species
occurs together with the white-sided jack rabbits, _L. californicus_ can
be recognized by the terminal black patch on the outside of each ear and
by the less extensive area of white on the flank. To the eastward, in
Tamaulipas, where only the black-tailed jack rabbit occurs, it too, has
extensively white flanks and some individuals lack the terminal black
patch on the ear.

A certain means for distinguishing the skulls of the black-tailed jack
rabbit from those of all of the white-sided jack rabbits has not yet
been found. The same is true of the skulls of the white-tailed jack
rabbit and the black-tailed jack rabbit in the Great Basin region of
Nevada. The skulls, at least of adults, of these two species, in the
region east of the Rocky Mountains can be readily distinguished by the
pattern of infolding of the enamel on the front of the first upper
incisor teeth; _L. townsendii_ has a simple groove on the anterior face
of the tooth and _L. californicus_, east of the Rocky Mountains, has a
bifurcation, or even trifurcation, of the infold that can readily be
seen by examining the occlusal surface of the incisor.

In Arizona, Vorhies and Taylor (1933:478) found the weight of 23 adult
males to average 5.1 (4.4-6.1) lbs. In that state, 70 pregnant females
averaged 2.24 (1-6) young per litter and the authors (_op. cit._)
thought that a female had three or four litters