220 University of California Publications in Zoology [Vol, 27 
are known locations of occurrence. The same wide range of adapt- 
ability is evinced in the matter of spawning places, as indicated beyond. 
Hyla regilla seems to have no period of inactivity at the lower 
altitudes in central California. Individuals are to be seen and the 
notes of others, coming from various sorts of retreats, are to be heard 
in every month of the year. More is to be seen and heard of the 
species during the spawning season, but there seems to be neither 
hibernation nor aestivation in the valley and foothill regions. Those 
hylas which live in the mountains must of necessity have a period 
during the season of low temperatures when they are hidden away in 
places where they will escape freezing. The extent of this period 
is unknown for the higher altitudes. In Yosemite Valley on February 
28, 1916, when the Valley floor was blanketed with snow to a depth 
of more than two feet, a chorus of hylas was heard in a snow-rimmed 
pool near the Merced River. In the Sacramento and San Joaquin 
valleys, during the heat of the summer hylas are sometimes to be seen 
in the damp vegetation about pools and stream margins, and the voices 
of individuals, hidden in safe retreats, are sometimes heard. 
This species is by no means a ‘ tree-toad, ’ so far as its choice of 
habitat is concerned. Indeed, it is only seldom that individuals are 
found in trees, or in other elevated situations. The greater part of 
the population in California, so far as my personal experience goes, 
is to be found close to, on, or under, the surface of the ground. In 
this respect regilla differs markedly from versicolor of eastern North 
America and arborea of Europe. In the habitats of the latter two 
species the relative humidity of the atmosphere is high during the 
summer months, and rains are then of frequent occurrence. The 
reverse is true in the range of regilla save in the humid northwestern 
coast belt. Death from desiccation would seem to be very much more 
likely in the dry summer air of interior California, Yet there are a 
few observations which show that individuals of regilla can survive 
in locations which combine high temperature with at most a very 
moderate amount of atmospheric moisture. Major Allan Brooks has 
told the writer of finding individuals of regilla during the daytime 
in the siding of a wooden house exposed to the full heat of the summer 
sun. They were six feet or more above the ground and in a place 
where there was no moisture save that in the bodies of the hylas them- 
selves. Mr. Harry J. Snook noted a hyla which regularly spent its 
days under the edge of a window awning on a house at La Jolla, 
San Diego County. 
