276 REPORT UNITED STATES ENTOMOLOGICAL COMMISSION. 
Yet it serves admirably to show the small area over which the locusts 
really breed iu great numbers, compared to the whole extent of the 
region. We have, also, in studying this question, so as to elaborate the 
geueral description given on p. 71, found it convenient to separately con- 
sider', 1, the Plains Area east of the Mountains; L>, the Mountain Area; 
the Plateau Area; 4, the Great Basin Area: and in doing so we have 
not only been guided by the experience of each of the commissioners, 
but have drawn from oilier available sources. 
The investigations of the past two years have led to a considerable 
enlargement of the Permanent region, as we intimated in our first map- 
ping of the region 340 that they might do when Idaho and Montana had 
been more fully studied. Our former estimate was that the region cov- 
ered, approximately, 300,000 square miles, whereas, owing to the inclu- 
sion of the western border of Dakota and larger portions of Western 
Wyoming, Utah, and Southern Colorado, as indicated in the map ac- 
companying this report, it will probably embrace more nearly 400,000 
square miles. 
We are particularly under obligations to Mr. Henry Gannett, E. M., 
who, as topographer for many years of llayden's Geological and Geo- 
graphical Survey of the Territories, has obtained very thorough personal 
acquaintance with the country under consideration. Tie has kindly 
aided us in every way in his power, and furnished most of the data rela- 
tive to the mountain and plateau areas. 
The Plains Area East of the Mountains. 
The vegetation of this area may be classified as follows : 
1. The grasses which, though of many distinct species, are, on the up- 
lands characterized by growing in bunches and never forming a sod, 
whence the general name bunch grass, by which they are popularly 
known. The commonest of these grasses on the plains is the Buffalo 
grass {Buchloe dactyloides). In the most southern of the Territories sev- 
eral species, known commonly as Grama grass, abound; the commonest 
of these is Festuca macrostachya ; 
2. Artemisia, or sage-brush, is perhaps the best known of the prod- 
ucts of the West, as it is certainly the most abundant. Of these the 
species which is the widest spread is A. tridentata; 
3. The cacti, of which the prickly pear, Opuntia, is the most abun- 
dant ; and 
4. Greasewood, a name applied to a variety of desert shrubs, the true 
greasewood being Sarcobatus (?) vermicularis. 
As may be noticed, these staples of the uncultivated soil are by no 
means varied, nor are they, with the exception of the grasses, of much 
economic value. 
Let us now take a glance at the general geographic distribution of 
these staples. 
340 First Report, p. 131. 
