1925] Storer: A Synopsis of the Amphibia of California 
147 
Philips Putnam has sent two larvae to the Museum of Vertebrate 
Zoology (now no. 8502) collected on July 2, 1922, near Lake Cushman. 
These two differ greatly in size, measuring respectively, 26 and 40 
millimeters in total length. The mouthparts of the smaller of these 
is shown in text figure KK. It seems, from the fragmentary data 
available, that Ascaphus probably spawns through a considerable 
period during the midsummer months and that the larvae do not 
metamorphose within a brief season as is the case with some of the 
land-dwelling Salientia. The size of the larger tadpole mentioned 
above and the date of capture suggest overwintering in the larval con- 
dition, as is practiced by Rana boylii sierrae in the Sierra Nevada of 
California. 
A young Ascaphus from Triple Trip Creek, Mason County, col- 
lected July 12, 1922, is 22 millimeters in head-and-body length. Judg- 
ing from the size attained by larvae, this specimen had probably meta- 
morphosed only a short time before it was collected. 
The life-history in relation to the environment. — Aside from the 
fact that it is the only member of the suborder Costata in the Western 
Hemisphere, Ascaphus truei is remarkable in that it presents what is 
probably the most extreme case of close adaptive specialization in 
relation to habitat of any of the Salientia of western North America. 
Its known geographic range includes only areas in the Canadian 
(and Transition?) Life-zone in the northwest coast region, where the 
streams are perennial, swift flowing, and of low temperature. In 
habits it differs markedly from the species of costate Salientia found 
in southwestern Europe, whose life-histories are well known. The 
larva is supplied with a special ‘sucker’ or holdfast which enables it 
to cling to rocks in the stream and thus avoid being carried to warmer 
waters in the lower altitudes. Removal from the stream habitat leads 
to the early death of larvae (Gaige, 1920, p. 6). The adults likewise 
require low temperatures for successful continuance. The conditions 
of life for this species are radically different from those for practically 
all of the other Salientia discussed in the present paper. Ascaphus 
evidently has to avoid even moderately high temperatures whereas 
most of our California amphibia seek to avoid desiccation and their 
temperature tolerance is relatively great. 
