MURID^ 111 



projecting in front of the anteorbital foramen nearly cutting it in 

 two; tail slender, scaly, thinly haired, shorter than head and 

 body ; pelage long, coarse, hispid ; form stout. 



Sigmodon hispidus eremicus Miiarns. ( Bristly ; hermit) 



WESTERN COTTON RAT. 



Above grayish buff coarsely grizzled with black, paler on 

 the sides; below dull white, the plumbeous bases of the hairs 

 showing through the white tips; feet grayish white; tail blackish 

 above, grayish below. 



Length about 280 mm. (11 inches); tail vertebroe 130 

 (5.10) ; hind foot 34 (1.35) ; ear from crown 17 (.67). 



Type locality, northwestern Sonora, Mexico, 30 miles south 

 of boundary monument 204, near the Colorado River. 



Western Cotton Rats are found in the bottom, lands of the 

 Colorado River from, its mouth north to. near Ehrenberg, Arizona 

 or further. But little is known about their abundance, but they are 

 probably common in places, and are likely to prove troublesome 

 as settlements increase and food and cover become more plenti- 

 ful. They seem to like thick cover such as cane patches and thicl< 

 weeds, and are likely to invade grain and alfalfa fields. 



They are prolific, as I caught females opposite Ehrenberg 

 in August containing six foetuses each. None of the females 

 that I caught near Yuma in March contained any. Their habits 

 seem to be similar to those of meadow mice in some respects. I 

 found sorghum stalks cut in coarse pieces six to ten inches long. 



Genus Reithrodontomys Giglioli. (Channel — tooth — 



mouse. ) 

 Upper incisors deeply grooved in front, appearing collec- 

 tively as if there were four instead of two; lower incisors small,_ 

 normal ; front upper molar with four roots, one being very small ; 

 coronoid process of lower jaw small, oblique; angular process in- 

 flected at lower edge; anteorbital foramen wide and rounded 



