1925] Storer: A Synopsis of the Amphibia of California 71 
Mountain. So far as known, A. calif orniense does not occur in the 
alpine lakes of the Sierra Nevada, though many of the lakes would 
seem to be quite suited to the requirements of the species. It must be 
recalled, however, that most of the alpine lakes in the Sierra Nevada 
to the south of Lake Tahoe date only from the last retreat of the ice 
of the Pleistocene-Recent glaciation. It may well be that prior to the 
last glacial epoch “tigrinum” inhabited a much more extensive range, 
including both the alpine and lowland portions of California, and 
that with the advent of glaciers in the Sierra Nevada the species 
became extinct there but persisted in the lowlands, whence through 
isolation, the slight change has come about which has developed the 
form calif orniense. 
The present arid condition of the Great Basin is probably a critical 
factor in restricting tigrinum to the mountainous regions along the 
north, east, and south sides of the Basin. Were this area to experience 
a moister climate the Tiger Salamander would in all probability 
spread to many parts of the region unoccupied at present, and it 
might possibly invade the Sierra Nevada on its eastern flank. 
Ambystoma macrodactylum Baird. Long-toed Salamander 
Ambystoma macrodactyla Baird (1850, p. 292). Original description; type 
from Astoria, Oregon. 
A [mby stoma]. macrodactylum, Cooper (1868, p. 486). Range. 
Ambly stoma macrodactylum, Cope (1889, pp. 95-97, pi. 25 [fig. 6], text fig. 
17). General account. 
Ambystoma macrodactylum, Van Denburgh (1916, p. 215). Occurrence 
near Fallen Leaf Lake. 
Ambystoma macrodactylum, Grinnell and Camp (1917, pp. 138-139, fig. 1). 
Range in California. 
Ambystoma macrodactylum, Stejneger and Barbour (1917, p. 10; 1923, 
p. 5). General range. 
Diagnosis. — Size moderate among California salamanders, total 
length 114 millimeters (4% inches or less) ; costal folds 11 ; toes all 
slender and long ; vomerine teeth in broadly A -shaped row across 
mouth mostly behind internal nares, in four separated groups ; body 
coloration uniform dark brown, except for irregular-margined stripe 
of light color down middle of back. 
Comparisons. — Distinguished from Plethodontidae by lack of naso- 
labial groove and by 11 instead of 10 or 12 or more costal folds ; from 
Triturus torosus by slenderer digits, presence of light stripe on back, 
and presence of four groups of vomerine teeth on roof of mouth ; from 
Ambystoma paroticum by lack of parotoid glands, presence of light 
stripe on back and 11 instead of 10 costal folds; from Ambystoma 
calif orniense by smaller size, longer digits, striped instead of spotted 
pattern of coloration, and arrangement of vomerine teeth in angular 
transverse row instead of U-shaped pattern ; from Dicamptodon 
