1925] 
Storer: A Synopsis of the Amphibia of California 
283 
SUMMARY 
1. The present paper is a general synopsis of current knowledge 
concerning the amphibia of California, together with the results of 
studies by the writer on the life-histories of the eight common aquatic 
spawning species. 
2. In the case of each species an effort is made to point out the 
factors in the environment which seem to be importantly correlated 
with the various stages in the life-cycle of that species. 
3. Comparison of the life-cycles of California forms with those of 
analogous species inhabiting northeastern United States indicates that 
here moisture conditions are apparently the more important, whereas 
in the east temperature plays the leading role. This is not to be taken 
to mean that the western species are removed from control by tempera- 
ture, but rather that the action of temperature in a critical way is 
largely suspended here by reason of the fact that the minimum and 
mean temperatures are, at all times, high enough to permit activity 
on the part of amphibians. 
4. The breeding season for the common aquatic amphibians of 
central California is advanced into the months of January to April 
(see text fig. F), in, or immediately following, the period of maximum 
seasonal precipitation. Amphibians here would be permitted, so far 
as temperature is concerned, to spawn at practically any time of year. 
However, water ordinarily becomes available only at some time after 
the beginning of the rainy period, and it continues available, on the 
average, only for about two months after the end of that period. 
Breeding activity of the local species is concentrated into this period, 
save as the species, individually, have special adaptive adjustments to 
circumvent the generally dry conditions prevailing in the summer 
season. 
5. Evasion of drought conditions is accomplished by several species 
by restricting their activities to small foothill streams ( Hyla areni- 
color, Rana b. boylii, Rana b. muscosa) ; others, the plethodont sala- 
manders, carry on their spawning operations in damp situations at, 
below, or above the ground surface, without reference to water in 
pools or streams. 
