300 MONOGRAPHS OF NORTH AMERICAN RODENTIA. 
species has been received is Fort Riley, Kansas. Further north, it extends 
eastward to the Missouri River and westward nearly to the Pacific coast. 
Lewis and Clarke observed it on the plains of the Columbia, where, according 
to Nuttall (as quoted by Bachman), it is abundant. Townsend obtained 
specimens on the Walla-Walla, and Dr. George Suckley on the eastern slope 
of the Blue Mountains of Oregon* and on the plains of the Columbia east 
of the Cascades. Dr. Suckley also speaks of it as occurring on the sage- 
plains north of Fort Boisé.+ Dr. J. G. Cooper speaks of it as common south 
of the Columbia and Snake Rivers, but rare of late years to the northward 
of these riverst A single specimen in the collection of the Smithsonian 
Institution, from Fort Crook, California, indicates its occurrence in Northern 
California. 1 found it abundant in Salt Lake Valley, Utah, and throughout 
Southern Wyoming and Northern Kansas eastward to within two hundred 
miles of the Missouri River. To the northward, it extends to the plains of 
the Saskatchewan, where, according to Richardson, it is abundant. Dr. Coues 
brought in specimens collected along the forty-ninth parallel, where he found it 
common.) Its limit to the southward is not so well known, but no specimens 
have been received from south of Middle Kansas and the Great Salt Lake 
Basin; south of these points, it is wholly replaced by the LZ. cadlotis var. 
texianus, whose range somewhat overlaps that of ZL. campestris. It is emi- 
nently a species of the great sage-plains, and its main range seems to be 
from Middle Kansas northward to the plains of the Saskatchewan, and from 
the eastern edge of the great plains westward to the Sierra Nevada Mount- 
ains. 
* Pacific R. R. Rep. & Expl., xii, pt. ii, p. 131. 
t Pacific R. R. Rep. & Expl., xii, pt. ii, pp. 104, 131. 
$ Am. Nat., ii, 536. 
§ Dr. Coues has published a monographic sketch of this species, inadvertently overlooked in pre- 
paring the bibliographical résumé of the subject which has been given on a preceding page. See Bull. 
Essex Inst., vii, 1875, p. 73 et seq. 
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