545 
Kansas, Nebraska, South Dakota, and North Dakota; north to 
southern Manitoba.’’* 
The following table gives the measurements of specimens from 
various localities. , 
Average length 
me a eae AS a Ratio of 
Number of specimens | puetl 
measured and places of | Head and ; |  O© tal 
capture. fe betel body Tail to length 
| | of head 
cient pees ie and body 
THe, |(koab agai | grnaeee a \eankoelel) Sota  ||soabas's | 
(imromicGhampaion county.../ 5:28 | 134 | 3.27 |. 83 | 2.01 | 51 | .63 
30 from Illinois outside of | 
Chanipaisnicounitsyseae a4) O24) | ss) | ede LOT Sil 20S soe 64 
47 (Coues’) chiefly from | | | 
Waiseonsim and Illinois.....| 4.96 |} 126 | 2.95 | 75 | 2.01 | 51 | .68 
It should be noticed that the specimens of Coues were appar- 
ently measured as alcoholics. If that be the case, the fact will ex- 
plain the shorter body and the consequent greater ratio of tail to 
body-length in his measurements. 
The maximum total length I have found, is 149 mm. The aver- 
age length of the hind foot for specimens in the county is 17.6, and 
the outside height of the ear averages 13.6 mm. The ratio of the 
length of the tail to the length of the body, which gives one of the 
most constant distinctions between this species and P. leucopus, gen- 
erally lies between .58 and .65. In a few cases it lies below these 
limits, but in only five instances in one hundred and fifteen speci- 
mens did it rise to .70: 
In all immature and many mature specimens the general color 
over the upper parts is dark gray with a shade of umber, giving 
a tint much resembling wood-brown of Ridgway’s nomenclature. 
This is darker towards the back, becoming nearly black along the 
middle line from the nape to the rump. The cheeks and back of the 
ears are smoky gray, as is also the upper surface of the tail and the 
* Osgood, W.H.,in ‘‘Revision of the Mice of the American Genus Peromyscus.”’ 
_ N. Am. Fauna, No. 28, p. 79. 
