206 University of California Publications in Zoology [Vol. 27 
individuals are seen in preservative which are very dark brown. The 
orange color on the hind legs and the black on the throat of the males 
are colors w r hich are apt to disappear after several years of preser- 
vation. 
History . — This distinctive species was first described by Baird in 
1854 on the basis of a specimen received from somewdiere in the north- 
ern part of the Province of Sonora, Mexico. Baird’s name affinis 
(probably an allusion to the similarity between this species and the 
eastern versicolor) proved to be preoccupied by an older name used 
by Spix, in consequence of which Cope in 1866 renamed the present 
form with the appropriate designation, aremcolor. 
Range . — This is a wide-ranging species, having been found as far 
east as Del Rio, Texas (Stone, 1903, p. 539), south in Mexico to Guana- 
juata, and possibly to the neighborhood of Mexico City (Cope, 1885, 
p. 387; 18875, p. 14), and north to Santa. Fe, New Mexico (Yarrow, 
1875, p. 524), and to the Grand Canon of the Colorado near the Coco- 
nino Plateau, Arizona (Stejneger, 1890, pp. 117-118). On the west 
it ranges through the mountains of southern California from Moun- 
tain Spring (Richardson, 1912, p. 606) and Mission Valley near San 
Diego (Storer, MS), to Little Rock Creek, Los Angeles County, and 
t^Nordhoffp Ventura County (Grinnell and Camp, 1917, p. 145). 
Yarrow’s (1875, p. 524) ascription of the species to Utah has been 
confirmed by Englehardt (1918, p. 79) who found it “common about 
springs, irrigation ditches, and rapidly flowing streams” in the 
vicinity of Bellevue, Washington County, altitude 4000 feet, on 
streams tributary to the Colorado River. Van Denburgh and Slevin 
(1921c, p. 54) record it from Ensenada, Lower California. 
Life-history . — Differing markedly from its one Pacific Coast con- 
gener, Hyla arenicolor is highly restricted ecologically. It is a canon 
species living chiefly on the boulders which line the courses of the 
streams which come down out of the mountains in the southwestern 
desert area. During the daytime (at least of the spring months) these 
hylas rest in niches on the surfaces of the boulders. I do not recall 
having seen one more than 12 inches away from the edge of a running 
stream. Their resting places vary from one inch or two up to perhaps 
24 inches above the water. When on the rocks the hylas crouch down 
with their legs and feet folded in beside or beneath the body. Out of 
the water the skin becomes slightly dulled and the irregular surface 
with its numerous small warts tends to break up mass reflections such 
as would come from a smooth-skinned amphibian under similar cir- 
