1925] Storer: A Synopsis of the Amphibia of California 
97 
be ‘yearlings’ ancl the group centering around 75 millimeters (60- 
90 mm.) would be two-year-olds. If, on the other hand, growth is 
continuous during the summer season then the animals in the table 
must be considered as all representing one year group, with a mean 
length of 70.5 millimeters being attained the first year. The matter 
cannot be decided. There are individuals of Batrachoseps attenuates, 
however (see table of measurements) considerably over 100 milli- 
meters in length and these, without doubt, are two years, or more, of 
age. It would seem that Batrachoseps arrives at sexual maturity when 
about two years of age, a condition parallel to that in the Hylidae, 
but different from that in other amphibians, most of which seem to 
require three years of growth before breeding. 
The life-history in relation to the environment . — Batrachoseps 
attenuates (and its generic relatives) is the smallest amphibian and 
the smallest land vertebrate in California. In the elongation of the 
body, increase in number of costal (vertebral) segments, reduction in 
size of limbs and feet, and elongation of tail we see in this salamander 
definite specialization toward subterranean life. In the Plethodont 
fauna of California the aboveground niche is filled by Aneides, the 
surface burrows of rodents are used by Ensatina, and Batrachoseps 
uses openings in the ground smaller than those available to either of 
the other two. There is no evidence that Batrachoseps actually bur- 
rows in the ground as Burke (1911) surmised, but I do believe that 
these salamanders are able to and do use the excavations made by 
earthworms and insects of various kinds. During the winter rainy 
period any sort of daytime cover is utilized as a temporary refuge; 
with the arrival of the dry season a definite movement into the ground 
removes the animals from danger of desiccation. They disappear 
regularly as the surface of the earth dries out and reappear imme- 
diately upon the advent of soaking rains in the autumn. Egg laying 
occurs in the latter part of the winter rainy period. Were the sala- 
manders to mature their sex products during the summer dry period 
while in underground shelters, intermingling of the sexes for the pur- 
pose of mating would be less likely to occur ; if they appeared at the 
surface of the ground in that time of year, death by desiccation would 
be much more likely for both themselves and their eggs. With the 
breeding period in the rainy season, danger of desiccation is avoided 
and food is available, both for the adults and later for the young, 
permitting the latter to make a considerable increase in size before 
the summer season arrives. 
