I 925 ] , Storer: A Synopsis of the Amphibia of California 165 
History. — Bufo alvarius was originally described from a single 
specimen said to have been obtained in the “valley of the Gila and 
Colorado/’ but which, according to Cope (1889, p. 267), was actually 
collected at Fort Yuma, California. 
Range. — This distinctive species is restricted in its range to south- 
ern Arizona and southeastern California. The easternmost locality of 
record in Arizona is for Tucson, Pima County (Ruthven, 1907, pp. 
505-507). Elsewhere in that state it has been found at Phoenix 
(Dickerson, 1906, p. 107; Van Denburgh and Slevin, 1913, p. 395), 
Tolladay’s Well (specimen in Mus. Vert. Zool.), and Sentinel, Mari- 
copa County, and at Maricopa, Pinal County (Stone, 1911, p. 223). 
Many specimens of the species were obtained by Slevin at Yuma, Ari- 
zona, September 10 to 21, 1912 (Van Denburgh and Slevin, loc. cit.). 
Cooper (1869, p. 480) mentions the species as occurring at Fort 
Mohave, Colorado Valley [= Arizona]. The specimens which formed 
the basis for this record have been in the Department of Zoology of 
the University of California for many years and are now in the collec- 
tion of the Museum of Vertebrate Zoology of that institution (nos. 
8264, 8265). Alvarius has been found in the Imperial Valley of 
California at Meloland (Grinnell and Camp, 1917, p. 144) and at 
Holtville. It quite probably has spread to other nearby localities in 
Imperial Valley; for as noted below the species is more aquatic than 
most bufos and it is therefore more likely to be dispersed by water 
movement in irrigation canals. 
Life-history. — Despite the fact that this is the largest toad in 
America north of Mexico and hence deserving of special attention for 
this reason alone, very little is known of its habits. Cooper (1868, 
p. 486) says that in the Colorado River Valley it has somewhat the 
habits of a frog. He reports (1869, p. 480) meeting with this species 
on May 28, 1861, at Fort Mohave, Arizona, where he describes it as 
‘ ‘ an enormous semi-aquatic species nearly as smooth as a frog. ’ ’ At 
Meloland, in the Imperial Valley, two individuals were dislodged in 
a field where some barley was being harvested on June 18, 1912. 
Another individual was taken under an electric light in Holtville 
at 8 o’clock on the evening of June 2, 1912. Accompanying the latter 
specimen is a note which states that the animal “ran” instead of hop- 
ping in the usual manner of a toad (Mus. Vert. Zool.). 
Ruthven (1907, p. 506) gives the following concerning the life- 
history of Bufo alvarius at Tucson, Arizona, as observed by Profes- 
sor J. J. Thornber of the University of Arizona. 
