208 University of California Publications in Zoology [Vol. 27 
varying: length, after which it will croak again. Often a small basin 
or pool on the course of the stream will have several males about it. 
These all face inward toward the center and tend to join together for 
a series of notes, then all are quiet for a time. But this is not an 
invariable rule. The notes carry well, so that to an observer stationed 
at any one point there are always hylas in voice. In fact along 
Tahquitz Creek on the night of March 25 there was a regular ‘ back- 
ground 7 of hyla, voices. In the quiet periods the animals keep their 
pouches partly distended. The note is a single utterance, resembling 
the quack of a duck (though not so blatant as that of a Mallard). 
Camp (MS) writes it cherk. According to Cope (1887, p. 14), Duges 
states that in Mexico the note reminded him of the bleat of a goat. 
Engelhardt (1917, p. 6) says that the note of Hyla arenicolor “is 
lower in pitch, but is otherwise very much like the bleating notes of 
Hyla versicolor.” The note differs markedly from that of our com- 
mon western tree-toad ( Hyla regilla) in being lower in pitch, some- 
what weaker in volume, and without any tendency toward a two- 
syllable sound such as is heard often from regilla. On two occasions, 
in San Diego County, the two species were heard side by side and 
there was not the slightest difficulty in distinguishing them. Two 
separate individuals of arenicolor which w r ere timed by the watch were 
croaking at one-second intervals. With all the males noted on 
Tahquitz Creek (fully 25 were located) only one female was seen. 
The chorus began about 4 p.m., soon after the sun had disappeared 
behind the San Jacinto Range, was strongest just after dark, from 
about 7 :30 to 8 :30 p.m., and continued on into the night at least until 
2 a.m. On other occasions males of Hyla arenicolor were heard croak- 
ing up to about 6 a.m., but only a few notes were given as late as that 
hour in the morning. The duration of the ‘ song 7 season is unknown ; 
on the morning of June 21, 1919, Canon Tree-toads were heard croak- 
ing in canons near the Mount Wilson trail. Dickerson (1906, p. 123) 
says “both male and female give a sharp high-pitched cry w T hen taken 
in hand.” The present w T riter has not heard this note, though he 
handled upwards of 25 of the animals in the field during 1923. 
The writer searched a number of creeks in southern California 
during March and April, 1923, in an effort to find the eggs of this 
species, but without avail. Miss Sarah R. Atsatt lent her efforts in 
this search with good result. On March 26, 1923, Miss Atsatt found a 
number of tadpoles in the upper reaches of Palm Canon Creek, River- 
side County. These proved to be Hyla larvae, not of regilla, and 
