216 University of California Publications in Zoology ITol. 27 
from pale gray through green, brown or red nearly to black ; usually 
marked with broad blotches of darker color in parallel rows on back. 
Comparisons. — Distinguished from all other Californian amphibia, 
save Hyla arenicolor, by presence of expanded adhesive discs on tips 
of all digits and from most species by small size (under 50 milli- 
meters) ; distinguished from Hyla arenicolor by slightly smaller 
average size, more slender form, wider head, smoother skin on upper 
surface, presence of dark stripe along side of head, and frequent 
exhibition of green on body of living animal. 
Description. — Form moderate, body depressed, head broad, limbs 
long; head broadly oval in outline from above, thin in profile, dorsal 
surface flat, muzzle rounded ; external nares nearly terminal, at begin- 
ning of indistinct canthus rostralis ; internarial width less than inter- 
orbital width ; upper labial region below canthus rostralis and orbit, 
slanting outward ; anteorbital region slightly longer than orbit ; orbit 
large; interorbital region flat, width three-fourths or more of length 
of orbit; tympanic membrane nearly round, separated by half or 
more its width from orbit, greatest diameter not more than one-half 
length of orbit, overhung by a slight ridge of skin extending back- 
ward from orbit ; angle of jaw slightly behind posterior margin of 
orbit; outline of lower jaw nearly semicircular; throat of male with 
loose wrinkled skin on vocal sac ; conspicuous, interaxillary fold of 
skin on breast ; free portion of upper arm shorter and more slender 
than forearm ; hand decidedly longer than forearm ; palm with one 
large elongate tubercle at base of inner digit; sesamoid tubercles 
small; digits long, tips dilated, with little or no webbing between 
bases, in order of decreasing length, 3, 4, 2, 1 ; body broad and flat, 
oval in outline from above ; hind limb only slightly stouter than fore 
limb ; femur and tibia about equal in length ; tarsus about two-fifths 
length of foot ; two metatarsal tubercles, outer much reduced, inner 
elongate ; sesamoid tubercles small ; toes slender, dilated at tips, fourth 
longest, third and fifth equal, second and first decreasingly shorter ; 
web reduced, margining toes to tips but scalloped deeply to distal end 
of first (basal) phalanx of fourth toe. 
Tongue rounded, moderately thick, greatest width half that of 
mouth at angles of jaws, broadly attached by anterior two-thirds to 
floor of mouth; maxillary teeth moderate in size, distributed along 
wdiole length of jaw; internal nares round, well up in anterior part 
of mouth and in from sides of upper jaw ; vomerine teeth large, few 
in number, in two rounded clumps directly between internal nares. 
Upper surface generally smooth, or with, at most, scattered, low 
rounded papillae ; sides and ventral surfaces with close-set flat-topped 
rounded papillae not more than 1 mm. in diameter, largest on sides 
of body and just posterior to interaxillary fold of skin; plantar sur- 
faces of feet with fine flattened papillae. 
Coloration (in life), upper surface highly variable, ranging from 
yellowish or grayish white through yellow, green and brown of light 
or dark shade to brownish black; narrow dark stripe along canthus 
rostralis to orbit and broad dark stripe from posterior margin of orbit 
to above forearm, constantly present in all color phases; upper lip 
below dark stripe whitish; ventral surface immaculate, white or pale 
yellow anteriorly, deeper yellow posteriorly, especially on concealed 
surfaces of limbs; gular vocal sac of male, blackish. 
