1925] 
St over : A Synopsis of the Amphibia of California 
287 
small size which makes possible the use of small crevices and spaces 
under rocks for purpose of shelter. Small size of adults also means 
less growth to be accomplished between transformation from the 
larval stage and arrival at the breeding condition. 
m. Bana caiesbeiana. The Bullfrog native to eastern United 
States has been introduced in several localities in California where 
permanent pools are available and it seems to have taken hold and 
to be thriving here. So far as the imperfect data at hand show, its 
seasonal schedule here with regard to time of emergence from 
hibernation, time of spawning, and length of time required for larval 
development, conforms closely to its calendar in the eastern states 
and seems not, as yet, to have been modified by local conditions. Com- 
paring this species with Bana a. draytomi, the native western ‘bull- 
frog,’ it would be expected that catesbeiana could here adopt a differ- 
ent schedule, and to its own advantage. But the fact that it evidently 
has not (so far as the few data at hand indicate) suggests that 
seasonal adjustment of stages in the life-cycles of amphibians are 
probably brought about by the action of natural selection through a 
long period of time. The general schedule is probably instinctive, the 
immediate schedule of any one year being dependent upon the par- 
ticular conditions of temperature and moisture in that year. 
