1925] 
Storer: A Synopsis of the Amphibia of California 
243 
This table indicates the general size of the tadpole population, but 
it does not necessarily portray ’ the seasonal programs of individual 
larvae. Thus metamorphosis had already occurred in one case by 
May 6 ; increasing numbers of metamorphosed individuals were prob- 
ably removed from the population after that date. The general tad- 
pole population, however, continued to increase in size up to June 20 
when most of the larvae were well on the way toward metamorphosis. 
Camp (MS) notes the finding of very large tadpoles, presumably 
of this species, in a reservoir near Sierra Madre on April 10, 1909. 
He states that tadpoles of this species are likely to be seen at almost 
every season of the year and he thinks it probable that in some places 
they take more than one year to arrive at the stage of transformation. 
From the evidence available in other localities I think that usually 
but part of one season is required for development from egg to frog, 
though exceptional instances might occur where the tadpoles would 
winter over and metamorphose the following spring. 
The size at metamorphosis in draytonii is only slightly larger 
than in boylii. Two specimens of the former from the Arroyo Seco, 
Los Angeles, collected May 15, 1921, are 27 millimeters in head-and- 
body length. In one of these the tail was nearly resorbed, a short 
stump about 3 millimeters long being all that remained. The other 
specimen was just beginning to transform and had a total length, 
from nose to end of tail, of 72 millimeters. A third specimen, on 
which the fore limbs had not yet burst through the opercular mem- 
brane, measured about 74 millimeters in length over all. These 
specimens were measured after being in formalin solution for two 
years. One larva collected on the Olema Creek marshes, Marin 
County, May 6, 1923, before preservation, measured 83 millimeters in 
total length. On the basis of size (age) groups it seems probable that 
Rana aurora draytomi begins breeding activities in its third year. 
The two species of tadpoles which by reason of large size and 
general similarity of appearance are likely to be confused in Califor- 
nia are those of the native Rana aurora draytonii and the introduced 
Rana catesbeiana. The ecologic preferences of the two are similar. 
Draytonii ordinarily accomplishes in one season (5 to 7 months) a 
degree of growth which takes two full years in catesbeiana, although 
the latter, prior to metamorphosis, reaches greater size than any 
examples of draytonii which have come to hand. Close comparison, 
side by side, of living examples of these two species, each of about 
