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ARVICOLA (HESPEROMYS) SONORIENSIS.— Le Conte. 
Sonora Field Mouse. 
A. Supra saturate cinereus fuscescente-cano leviter mtermixtus, subtus 
albescens. Capite elongate, auribus magnis. Cauda modica. 
CHARACTERS. 
Above, dark grey slightly mixed with brownish ; breast whitish. Head long 
and pointed legs large j tail moderate. 
SYNONYME. 
Hesperomys Sonoriensis. — Le Conte, Proc. Acad. Nat. Sci., Phila., Oct., 1853, 
p.-413. 
DESCRIPTION. 
Hair above dark cinereous or slate-colour, slightly mixed with brownisn 
grey, more thickly on the head, nose, and behind the ears, and with grey 
on the sides ; beneath whitish, except on the throat, which is mixed slate- 
colour and whitish. Head elongated, pointed ; ears large, oval, hairy 
both within and without, and with a distitict, narrow grey margin. 1' eet 
covered with short, whitish brown hair. Tail moderate, above dark biowr, 
beneath paler. 
DIMENSIONS. 
Length, - 
“ of head, 
li ears, 
“ fore leg, 
“ hind “ 
“ tail, 
Inches. Lineb 
3 3 
1 2 
4 
1 
1 8 
1 9 
“ Resembles in some degree the H. Leucopus. Collected by the Bound- 
ary Commission, under Major Graham.” (Le Conte.) 
