202 BULLETIN NO. VII. 
Lemmings) tend to confuse the effect of climate, in which case 
we may understand why variety borealis may be occasionally 
found as far south as Moorhead, Minnesota (a fact not hitherto 
reported) and why, on the other hand almost typical riparius 
sometimes reaches Alaska. It is, at any rate, certain that this 
section (Myonomes) of Arvicola when it becomes acclimated 
takes on the characteristics of an arctic variety—this our ex- 
planation—with larger body and smaller extremities. This 
phase constitutes variety xanthognathus or the yellow cheeked 
variety of Alaska and the arctic regions. The relative size of 
true riparius and borealis will be found given under the osteology 
of thelatter. (Anatomical details of the present species below.) 
We have kept specimens of the meadow mouse in confine- 
ment and found it an engaging pet easily domesticated and 
accommodating itself to its new circumstances well. It is sur- 
prising how little the fore feet are used in its daily activities. 
Although perhaps less amusing than the white-footed mouse 
in confinement it is sprightly and active. The sight is rather 
. defective and the senses not acute. Its food consists largely 
of grasses and the stomach will usually be found full of green 
material although the grain is also highly relished. I have 
been able to detect no preference between the various cereals. 
Wheat is secured in the field by cutting the halm off repeatedly 
until the ear is brought within reach. The meadow mouse is 
not fossorial strictly, excavating at most but shallow runs 
below the surface. The teeth are used expertly in gnawing 
through boards if a light is seen through, but not so muchso 
apparently as in the case of our domestic mice. These wild 
mice are very fond of water, lapping it eagerly if for a few 
hours deprived of it. They are also very neat in their per- 
sonal habits. They fall an easy prey to birds of prey on 
account of their imperfect sight but would otherwise multiply 
very rapidly. They like well onsunny afternoons to play about, 
running through the galleries or roads they have made through 
the high grass. These paths lead from one covert to another 
and are not burrows but pass under roots or fallen logs or 
boards or brush piles and are beaten smooth by constant use. 
On such isolated places as bushy islands in the middle of some 
river they become numerous and venturesome. 
It has already been mentioned that the field mice are now 
found in greater numbers than elsewhere, upcn the low grass- 
covered islands in our rivers, where, during the summer, at 
least, they are to a certain extent, exempt from forays of 
