366 GEOLOGICAL SUEVEY OF THE TERRITOEIES. 



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 of the fortieth parallel, including 

 Colorado, Wyoming, Northern Utah, Western Idaho, Central and North- 

 ern Montana, and wa s thus enabled to observe in a superficial way th e 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 Eiver to Wal- 

 lula, here as well as at Eeno 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 groui)s 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 sferuck me, and I was impressed with its distinctness 

 from that of the Eastern States. I have seen few of these from Cali- 

 fornia. Among the family of ants (Formicidce), there was one form 

 characteristic of the plains which does not occur on the Pacific slope. 

 This is the Fogonomyrmex 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 Yalley, Colorado. Its nest, forming large elevations in cleare<i 

 spaces sometimes six or eight feet in diameter, is one of the character- 

 istic sights on the plains. 



Among the Lepidoptera, family Bomhycidw, there are several forms 

 peculiar to the central district, notably the genus BirpMa (Coloradia), 

 FuleucophcBiis, Gloveria (Ifesistesoma), Hemileuca, Juno, and Hera, and 

 Plaiysamia gloverii. 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 Phalcenidce, or geometric moths, are richly developed in the 

 Pacific 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 

 Eocky 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, Galop- 

 tenus spretus is thoroughly characteristic of the Central province. It 

 does not occur in the Pacific and only breeds temporarily in the Eastern 

 province, and its natural limits define well those of the province itself. 

 It ranges up to latitude 53^ N. on the North Saskatchewan and south 



