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University of California Publications in Zoology [Vol. 27 
83 millimeters total length and with hind limb buds in evidence (third 
stage larvae of Duges), shows the following important differences: 
Bana aurora draytonii 
Bana catesheiana 
Larva from pond in marshes 
at south end of Tomales Bay, 
Marin County, California. 
Larva from creek pool near 
Farmington, San Joaquin 
County, California. 
Snout 
More pointed in outline as 
viewed from above. 
More rounded in outline. 
Eyes 
Rather close together. 
Farther separated. 
Body 
Broadest posterior to spiracu- 
lum, ended behind abruptly. 
Broadest anterior to spiracu- 
lum, tapering behind gradu- 
ally into tail. 
Tail 
Greatest height posterior to 
midpoint, bluntly tapered to- 
ward end. 
Greatest height anterior to 
midpoint, sharply tapered to- 
ward end. 
Broader at base as viewed from 
above. 
Narrower at base as viewed 
from above. 
Coloration 
Ground color of dorsal and lat- 
eral surfaces of body, dark 
browns and yellows. 
Ground color of dorsal and lat- 
eral surfaces of body, olive 
green of light or dark tone. 
Spots on body 
Diffuse margined, more than 1 
mm. in diameter. 
Sharp -margined, not over 1 mm. 
in diameter. 
Under surface 
Center of belly with pinkish 
iridescence, margins mixed 
iridescent and blackish in fine 
pattern. 
Center of belly whitish, not 
iridescent, margins mottled 
with dark pattern of large 
size. 
Tail 
Mottled with light spots. 
With small dark dots as on 
dorsal surface of body. 
The life-history in relation to the environment. — Rana aurora 
draytonii shows less special adaptation to the climatic conditions of 
the Pacific Coast than many of the other species of western am- 
phibians. It seeks and remains in situations where the water supply 
is permanent and therefore has no need to develop special adaptive 
responses to the semi-arid climate. Its local occurrence is limited to 
those places in which there are permanent pools either natural or 
artificial. General dispersal over the country probably occurred at 
some time in the past when conditions were less arid. Some spreading 
probably occurs during unusually wet winters, but the rate of such 
dispersal must be slow at best. Draytonii spawns very early in the 
year, on the average in January and February, with extreme limits 
