86 University of California Publications in Zoology [Vol. 27 
The forty larvae collected on September 30, 1917, range from 54 
to 142 millimeters in total length. Omitting the longest the others 
range evenly, without a significant break, from 54 to 119 millimeters. 
The gradation in size is so even as to suggest that they all came from 
eggs laid in the spring of that year. If the general run of individuals 
could increase from 15 to 17 millimeters (the length at hatching) to 
the various sizes indicated, it seems possible that one individual, par- 
ticularly fortunate as to food, might increase from 15 to 142 milli- 
meters in one season. 
In certain other amphibians it has been found that little growth 
occurs during the winter season (see, for example, Bana b. boylii, 
p. 255). That this condition obtains in D. ensatus is suggested by the 
following facts. The largest larva in the group just discussed is 142 
millimeters long. It was collected on September 30. The larva seen 
in Costen Lake on June 18 was estimated to be about 150 millimeters 
long. The only larvae larger than these are the two collected at Fair 
Oaks, Humboldt County, on August 24, 1910. These measure 208 
and 228 millimeters respectively, in total length. It seems likely that 
these were in their second (or third) summer of growth. 
In the series of transformed animals at hand only three of the 
eleven specimens measure less than 200 millimeters in total length. 
This seems significant in relation to the probable size of the larvae 
at transformation. With most species of amphibians, individuals of 
small or medium size constitute a majority of those seen in the field. 
While selection of the larger individuals may possibly be practiced 
by some collectors., it is generally true that specimens are taken, big 
or small, as they can be obtained. Large frogs often escape by reason 
of greater wariness or better ability in leaping, and this tends to offset 
any selective action on the part of a collector. The case with Dicamp- 
todon ensatus is different. It is generally considered as a ‘rare’ species 
and in the adult form has no particular means of escape. Collectors 
are therefore likely to bring in every individual which comes to notice. 
Were it a common thing for the larvae of this species to transform at 
small size (between 125 and 200 millimeters), more small non-gilled 
individuals would be expected in our collections. The few small-sized 
adults which have been collected may ^represent individuals which, 
because of changed conditions in the water, transformed earlier than 
is usually the case. Cope (1889, p. 49) states that the size at loss of 
branchiae in tenebrosus [= ensatus] is 5 inches 9 lines (146 milli- 
meters). The number of specimens examined is not given. The same 
author (p. 506) mentions a larva 250 mm. in length. 
