120 University of California Publications in Zoology [ Vou. 17 
are blotched and spotted like R. b. sierrae, and many show cross-bars 
on the tibia. The skin is usually thickly studded with brownish, hispid 
points, as in many boylii, but in the type it happens to be smooth. The 
outer metatarsal tubercle is sometimes rudimentary. The head-width 
enters the body-length from two and one-third to two and two-thirds 
times. 
Remarks.—The two very young specimens from Little Rock Creek 
Canon show the light head patch of R. b. boylii, and the flexed tibia 
extends beyond the anus as in that form. There is thus a good chance 
that on the desert slope of the San Gabriel Mountains the frogs are 
boylit rather than muscosa. The Phrynosoma blainvillii of the north- 
ern San Gabriel Mountains (Pine Flats, Barley Flats, and the Upper 
Tujunga Canon, 5000-5500 feet), and of the Sierra Liebre, is of the 
northern subspecies, Ph. b. frontale; the frogs here discussed may offer 
a parallel case. 
Rana boylii muscosa inhabits the deeply cut valleys and gorges of 
the San Gabriel, San Bernardino, and San Jacinto Mountains, from 
at least the Arroyo Seco Canon near Pasadena, on the northwest, to 
Keen’s Camp, Riverside County, on the southeast. It readily climbs 
the steep rocks bordering the cafon streams, employing for this pur- 
pose the enlarged tips of the digits, and sits far above the water during 
the day; when alarmed it dives directly into the stream, kicks up the 
silt with its hind legs, and buries itself in the mud, so that pursuit is 
rendered difficult. 
Rana boylii sierrae, new subspecies 
Sierra Nevada Yellow-legged Frog 
Type—Female, adult; no. 3734, Mus. Vert. Zool.; Matlack Lake, 
10,500 feet altitude, two miles southeast of Kearsarge Pass, Sierra 
Nevada, Inyo County, California; June 26, 1912; collected by H. 8S. 
Swarth; orig. no. 9901. 
Synonyms.—Rana aurora, part (Stejneger, 1893, p. 225); Rana 
pretiosa, part (Stejneger, loc. cit., p. 226) ; [2] Rana pretiosa (Yarrow 
and Henshaw, 1878, p. 1632), part [Lake Tahoe]. 
Diagnosis—With the general characters of Rana boyli boylii, but 
hind leg usually shorter and head relatively narrower; tympanum 
smoother ; and light patch on top of head wanting. 
Description of type-—Vomerine teeth rudimentary, on two oblique 
ridges nearly meeting between and slightly behind nares (see fig. 2) ; 
