MAMMALS OF MINNESOTA. 195 
The close relationship between this variety and H. rutilus 
was first shown by Coues in the Proceedings of the Academy of 
Natural Sciences of Philadelphia in1874. The differences con- 
sist in a somewhat greater size and a considerably greater 
development of the extremities in accordance with the general 
law that the extremities are shorter in northern individuals of 
a species extensively distributed than in southern examples of 
the same species. If the size be really less than in H. rutilus 
it forms an exception to the remainder of the law that the 
absolute size is usually greater. The colors are darker, 
especially the sides which are a grayish brown instead of hav- 
ing the milk tinge of H. rutilus. 
In general form there is nothing to distinguish this interest- 
ing animal from the common field mouse. It can be at once 
distinguished, however, by the color and the greater develop- 
ment of the ears. These organs appear quite prominently 
above the fur and are hirsute, while near the base of the anti- 
tragus is a tuft of stiff hairs longer than the ear itself. 
The middle of the back from the crown to the root of the tail 
is of a strong, rusty red color, given a grayish cast by numerous 
black hairs sprinkled through the pelage. On the sides the 
red is largely replaced by brown. so that the resulting color 
is much as in Arvicola riparius. The bases of the hairs every- 
_where are plumbeous. About the face the color becomes a 
grizzly gray, in old specimens at least. Below greenish white 
of various degrees of purity is the prevailing color, the fur 
being much lighter color than in A. riparius. The feet partake 
in the same coloration. The tail is distinctly bicolored, the upper 
surface being, as usual, darker than the prevailing color of the 
back. The vibrisse are rather longer than in A. riparius. Con- 
siderable variations in the coloration occur, the breadth of the 
red stripe especially being far from constant, either in width or 
intensity. 
The following measurements may be taken as a very fair 
showing of the size of adults, the first being taken in autumn, 
the second in spring, and in adjacent localities: 
= Total Head * N N F Hind 
NUMBER. ighpth Ga edie Tail. |to a Sere faut, foot. 
By ses (OH CTIA OPN 00 ove! s sc. v aclaras 5.70 4.0 | 1.70 | 0.50 | 0.95 | 0.31 Opt 
Zee B.C 1) nea ae 4.90 oo | Le20nl Ordon) Loo | 0-40 0.70 
ANETAGEOS (56.6 crete 5.13 Sabai eie sou O-44a0V85: (kOs37 | 0.72 
Coues’ averages, published in his monographs of North 
American Rodentia, are placed in the third line for conven- 
ience of comparison. 
