CHAPTER XII. 
NOTE ON THE GEOGRAPHICAL DISTRIBUTION OF THE 
ROCKY MOUNTAIN LOCUST, ILLUSTRATED WITH A COL- 
ORED ZOO-GEOGRAPHICAL MAP OF NORTH AMERICA. 
In the first report of the Commission (Chapter VI, p. 136) we traced 
the geographical limits of the Rocky Mountain locust, giving its east- 
ern, northern, western, and its approximate southern limits; the latter 
being farther perfected and revised in Chapter VI of our second re- 
port, and in the colored map accompanying the report. On page 108 
of our second report we also showed that the geographical limits of the 
western cricket (species of Anabrus) “are probably nearly or quite co- 
extensive with those of the Rocky Mountain locust.” 
For the convenience of the general reader, as well as of naturalists, 
we have, with the permission of Dr. F. V. Hayden, reproduced, with 
certain minor corrections, a colored zoo-geographical map of North 
America. It was originally prepared to illustrate the distribution of 
certain fresh-water Crustacea (Phyllopods) and appears in the Twelfth 
Annual Report of the United States Geological Survey of the Terri- 
tories. Upon sending a proof to Mr. J. A. Allen, who has paid special 
attention to the geographical distribution of the mammals and birds, 
he kindly returned it without corrections, stating that it agreed with 
his views as to the limits of the zoological regions and provinces. 
Another copy was sent to Prof. A. E. Verrill, who made some corrections 
in the eastern province around the Bay of Fundy, and a few less im- 
portant changes. Hence it is believed that the map will represent with 
tolerable accuracy the zoological distribution not only of the insects in 
general, but of nearly all the other classes of the animal kingdom, ex- 
cluding the marine forms. 
The range of the Rocky Mountain locust is co-equal with the light- 
brown area, i. e., the Central Province, except that it will probably not 
be found south of the isothermal of 72°. This province is also the homo 
of the species of Anabrus or Western Crickets. These are among the 
most characteristic Orthoptenus insects to be found in this province, 
although there are many other species not to be found elsewhere. On 
the other hand, the common red-legged locust, Caloptenus femur-rubrum , 
occurs all over the Boreal or Canadian, the Eastern, the Western 
(Pacific), as well as the Central Province, so that it ranges over the 
whole of North America south of the limit of trees and north of Mexico 
and Lower California. The distribution of a third species, Caloptenus 
atlanis , is nearly co extensive with that of C. femur-rubrum, although it 
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