16 University of California Publications in Zoology [Vol. 27 
The spawning seasons of the California species (see fig. F), are 
advanced two to three months ahead of those of the species in Texas 
and New York. The only species which spawn in California during 
the summer months do so by reason of special adjustments in the 
matter of moisture. 
The amphibians, because of their dependence upon conditions of 
temperature and moisture, are highly suitable material for indicating 
differences between various environments with respect to these factors. 
Normally, the egg and larval stages of Salientia develop in water. 
Sampson (1900), however, has described the breeding habits of a 
number of exotic Salientia wdiich in one way or another depart from 
the conventional method. Some species deposit their eggs in a mass of 
froth suspended above water ; others, such as the Surinam Toad ( Pipa 
americana) and the Obstetrical Toad (Alytes obstetricans) of south- 
western Europe, carry the eggs or young for longer or shorter periods 
of time. In the tropical rain-forests, where much of the animal life 
is restricted to the arboreal habitat and where terrestrial pools of 
water are at a premium, certain species of Salientia pass both the 
egg and larval stages in the protecting coat of gelatinous material, 
‘hatching’ as perfect though miniature replicas of the adult (see 
Noble, 1923). The atmosphere there is sufficiently humid so that 
there is no danger of desiccation to eggs laid out of water. 
Hall (1922) has made an experimental test of the vital limit of 
exsiccation in various animals, including one species of frog ( Rana 
pipiens) and a species of salamander (Amby stoma punctatum ) . By 
confining the animals in a chamber supplied with a current of well 
oxygenated but dried air, it was found that a frog could be reduced to 
a condition of apparent death (the skin becoming dry) with a loss 
of 50 per cent of the water contained in the body or 41 per cent 
of the total live weight, after which it would recover upon being 
placed in water. The salamander showed similar ability to withstand 
desiccation — loss of water up to 47 per cent of the body weight being 
followed by recovery upon immersion in water. In one instance an 
exsiccated animal when returned to water regained 97.7 per cent of 
its loss within 24 hours. It would be of great interest to determine 
the vital limits of exsiccation for some of the species of amphibians 
discussed in the present paper; Rana pipiens is a marsh-inhabiting 
frog and could scarcely be expected to exhibit so high a degree of 
resistance to loss of water as some of the desert toads. 
