FIELD BOOK OF MAMMALS 



are gentle and easily cared for. They are cleanly in habits 

 and, as far as I am aware, are not carriers of disease. While 

 most active after sundown, they are not infrequently seen dur- 

 ing the daytime and are curious enough to come out and 

 investigate any unusual disturbance. Wood Rats are active 

 throughout the year and do not hibernate. 



In the northern part of their range, Wood Rats raise but 

 one brood of young a year, but in the regions of mild winters 

 several litters a year is more the rule. These litters contain 

 from three to six individuals. 



The pelage of the Wood Rat is quite soft, but it is of no 

 commercial value as fur; at least no market for it has yet been 

 established. The flesh of these Rats is white and palatable, 

 being eaten by some of the western Indians, but because the 

 animal bears the name of Rat it is not apt to become a com- 

 mon article of diet with most people. 



Subfamily Microtinae. Voles and Lemmings 



Cricetine rodents with flat-crowned molars; molar pattern 

 prismatic, composed of angular figures; habit terrestrial, 

 fossorial, or semiaquatic. 



Genus Synaptomys^ 



Dentition: Incisors, J ; Canines, ^ ; Premolars, <] ; Molars, 3=16. 



Lemming Mouse. — Synaptomys cooperi 



and related forms 



Names.- — Lemming Mouse; Bog Mouse; Bog Lemming. 



General Description. — Externally very much like a small, 

 short-tailed Meadow Mouse, but differing in cranial and 

 dental characters. Form thickset; tail very short; pelage 

 coarse; incisors orange; upper incisors with longitudinal 

 groove ; rostrum very short ; molars rootless ; nail of first digit of 

 forefoot flat and strap-shaped; plantar tubercles six; dwelling 

 in bogs and swamps. Plate XXX. 



Color. — Sexes colored alike; seasonal variation not very 

 great. 



' For a full revision of this genus see A. B. Howell, North American 

 Fauna, No. 50. 1927. 



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