366 GEOLOGICAL SURVEY OF THE TERRITORIES. 
Gray in their preliminary notices of the results of their botanical re- 
searches in connection with Dr. Hayden’s U.S. Geological Survey of 
the Territories. 
In traveling in the summer of 1877, in pursuance of the work of the 
_ United States Entomological Commission, I passed rapidly over a large 
area of the Central province lying north ot the fortieth parallel, including 
Colorado, Wyoming, Northern Utah, Western Idaho, Central and North- 
ern Montana, and was thus enabled to observe in a superficial way the gen- 
eral features of the flora and fauna nearly up to the British line. I was im- 
pressed with the resemblance of Central and Northern Montana to North- 
ern Utah, the insect-fauna being apparently nearly identical. Doubtless 
this insect-fauna extends northwards into the Upper Saskatchewan val- 
ley as far as the southern limit of trees, there being much less intermix- 
ture with Canadian forms than might be expected. Then crossing the 
Sierra Nevada, and going overland to Oregon, I was able to trace the 
gradual passage of the Californian insect fauna into the Oregonian, with 
some Canadian forms; and by passing up the Columbia River to Wal- 
lula, here as well as at Reno in Nevada, to perceive the great differences 
between the fauna of the Pacific slope and that of the plains and deserts 
of the Central province. 
In briefly reviewing the different orders of insects, other than Cole- 
optera, which have been so fully elaborated by Dr. Le Conte, and cer- 
tain groups of Crustacea, we will begin with the Hymenoptera, and 
point out a few characteristics distinguishing the Central from the 
Pacific provinces. In 1865 and 1866 a large number of Coloradian fos- 
sorial Hymenoptera passed under the writer’s hands, Mr. Cresson hav- 
ing previously described from this material a large number of Colo- 
radian Hymenoptera of all families. The richness of the hymenopterous 
fauna of Colorado struck me, and I was impressed with its distinctness 
from that of the Eastern States. I have seen few of these from Calli- 
fornia. Among the family of ants (Formicidae), there was one form 
characteristic of the plains which does not occur on the Pacific slope. 
This is the Pogonomyrmex occidentalis (Cress.). I have seen its large 
hills at Brookville, Kans., and observed them in Colorado and Utah, 
and in Reno, at the base of the Sierra Nevada, but not west of that 
point. It ranges, according to Mayer, south into New Mexico, and San 
Luis Valley, Colorado. Its nest, forming large elevations in_cleared 
spaces sometimes six or eight feet in diameter, is one of the character- 
istic sights on the plains. 
Among the Lepidoptera, family Bombycidw, there are several forms 
peculiar ‘to the central district, notably the genus Dirphia (Coloradia), 
Huleucopheus, Gloveria (Mesistesoma), Hemileuca, Juno, and Hera, and 
Platysamia gloveriit. The family is feebly represented in the Central 
province, but richly so by numerous species on the Pacific slope, which 
do not appear east of the Sierra Nevada. 
The Phalenide, or geometric moths, are richly developed in the 
Pacifie province, and but poorly in the Central province, owing to the 
absence of deciduous trees; of those found in the latter some occur 
west of the Sierra Nevada, and some are peculiar to the plains and 
Rocky Mountains. 
Of the Orthoptera there is a large number of species peculiar to the 
plains which I did not observe in the Pacific States; of these, Calop- 
tenus spretus is thoroughly characteristic of the Central province. It 
does not occur in the Pacific and only breeds temporarily in the Eastern 
provinee, and its natural limits define well those of the province itself. 
It ranges up to latitude 53° N. on the North Saskatchewan and south 
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