256 University of California Publications in Zoology [Vol. 27 
lected in the creeks in the spring of the following season show prac- 
tically no increase in size. Thus, five young collected in Papermill 
Creek near Tocaloma, Marin County, on May 5, 1923, measure only 
22.7 to 26.1 millimeters in head-and-body length. These figures are 
to be compared with those just mentioned, of animals taken August 7, 
1922. Growth evidently begins with the advent of warm weather, 
as four specimens collected along this same creek on July 9, 1922, 
measured from 31.5 to 38.5 millimeters in head-and-body length. 
The tadpole of Ra\na boylii boylii , while not grossly different from 
the larvae of other California Salientia, presents a peculiarity in the 
form and number of the ‘teeth’ which line the region about the 
mouth. There are seven rows above the mouth and five below and the 
series below the lower lip are on a rather loose flap of skin which 
permits of more than the ordinary amount of movement. Of the 
teeth superior to the mouth only the topmost row is complete, the 
others are divided, and each successive row becomes shorter until the 
seventh is but a short lateral row on each side of the mouth proper, 
each half containing but a very few teeth. The five ventral rows all 
extend across the ‘lower lip.’ 
The form of mouthparts in the present species is strongly sug- 
gestive of that of the larva of Ascaphus truei as described by Gaige 
• (1920). Ascaphus has 13 rows of teeth, three above and ten below 
the mouth, while Rana boylii has twelve rows with seven above and 
five below. Mrs. Gaige states (p. 6) that the tadpoles of Ascaphus 
“cling with the mouth to the stones in the creeks.” Boylii has not 
been observed to do this in the case of specimens collected in central 
California. It may be a mere coincidence that these two Salientian 
larvae are provided with such an elaborate series of larval teeth, but 
it seems significant that such development has appeared only in those 
two species in this order which have become restricted completely to 
life in flowing streams, even though the two species belong to separate 
suborders. 
A generous sample of the boylii population from any one locality 
on a particular date usually reveals frogs of two distinct sizes, some 
under 40 millimeters and others ranging from 50 to 70 millimeters in 
head-and-body length. I take this to mean that at least two years 
are required for growth to adult size. The ‘yearlings, ’ which consti- 
tute the smaller size group, take no part in breeding activities. Some 
of the frogs in the ‘adult’ category are, for this species, large and 
‘pachydermous’ and thus give the appearance of being decidedly aged. 
