1879. ] A Contribution to the Zoology of Montana. 437 
large and projected from their mouths. These precocious larve 
were evidently air-breathers, and hopped about, presenting a 
curious appearance as they dragged their large tails after them. 
I found some adult specimens of Amblystoma mavortium also, 
along the waters edge. These observations were made on the 
11th of August, 1876. 
Chorophilus triseriatus Wied—This widely distributed species 
I obtained at Franklin, on the Utah-Idaho boundary, and subse- 
quently found it very common in the ruts of the wagon trails on 
the plains east of Fort Benton. In the latter locality it was 
generally of a bright green color. 
Bufo dipternus Cope, sp. nov.—This toad I found abundant on 
the plains north of the Missouri river east of Fort Benton, in the 
wagon ruts of rain-water, in company with Spea bombifrons, etc. 
It is of about the same size as the latter species, and resembles it 
in various ways; it doubtless has similar fossorial habits, as it 
is furnished with a tarsal shovel of the same proportions, and has 
in addition a second tarsal bone produced into a digging spur. 
The prefonta! bones are thickened in the same way, although not 
to the same extent as in Sea bombifrons, a condition, no doubt, 
directly connected with the habit of pushing aside the earth 
while excavating burrows with the feet. It is easily distinguish- 
able from the Spea, by the ordinary collector, by its large dorsal 
spots, which are much better defined than are the small ones of 
the S. dombifrons. I did not find the Bufo dipternus south of 
the Missouri river ; there its place is occupied by a very distinct 
species, 
This Bufo differs from the B. lentiginosus and all its sub-species 
in the presence of two well-developed fossorial tarsal spurs, and 
in the large size of the internal one. In this respect it need only 
be compared with the B. compactilis Wiegm., from South Texas 
and Mexico. It is distinctly related to the latter, but is separable 
from it as a distinct species on account of (1) its much smaller 
size, reaching only half the dimensions, (2) the smaller size and 
obscurity of the tympanic membrane, which is only one-third the 
diameter of the eye-slit, while in B. compactilis it is one-half the 
Same diameter, and is well defined, (3) the larger and truncate 
external tarsal spur, and (4) the coloration, which is quite distinct. 
The head in the adult Z. compactilis is also distinctly shorter. 
There are two faint straight supraorbital ridges, and a postor- 
bital but no supratympanic ridge. The supraorbitals are united _ 
