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 xantliognailms 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 the latter. (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 much so 

 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 on sunny 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, upon the low grass- 

 covered islands in our rivers, where, during the summer, at 

 least, they are to a certain extent, exempt from forays of 



