1925 J St over: A Synopsis of the Amphibia of California 
11 
The matter of refuge for adults is highly important at all times to 
all amphibians. Some species, as for example, most of the true frogs 
( Bana ), must be in the presence of water at all times. A certain few 
species such as the wood frogs (Rana sylvatica and Ran a cantabrig- 
ensis) of eastern and northern North America are able to live on the 
damp floor of forests, but other ranas require marshes, streams, or 
ponds for their successful continuance as individuals, without regard 
to their respective species requirements in spawning. Rana catesbeiana 
is an extreme example, being able to persist only in the presence of 
permanent bodies of water. Rana a. draytonii is similarly restricted, 
the only apparent exceptions being where it lives in water tunnels the 
atmosphere of which is at all times saturated with moisture. Species 
of small size, such as Hyla regilla, can hide away in small crevices and 
so find in many places adequate shelter against desiccation, freezing, 
or capture by enemies; this particular species is therefore found in 
a great variety of surroundings. 
The true toads ( Bufo ) and spadefoots ( Scaphiopus ) are provided 
with digging equipment (varying in development in the several 
species of the former group and developed to an extreme degree in 
the latter) whereby they are able to dig themselves suitable individual 
shelters in which to spend the daytime when the amount of atmos- 
pheric moisture is dangerously low. The species of terrestrial toads 
of the American desert ( Bufo cognatus and B. woodhousii [pi. 11] ) 
are provided with foot tubercles which, in appearance and hardness, 
resemble the ‘spades’ of Scaphiopus and are presumably used for the 
same purpose — to 1 dig in ’ and avoid desiccation. 
The salamanders, lacking suitable digging equipment, are found 
to inhabit places generally moist, and where natural crevices or other 
kinds of daytime retreats are available for the protection of the 
adults. 
