304 VERTEBRATE ANIMALS OE THE UNITED STATES 



numbers all the other mammals in a region. They frequently enter 

 and live in dwellings, and may be distinguished from the house-mouse 

 by their snow-white feet and under parts. 



Key to the United States Species of Peromyscus 



ai Length over 120 mm. 

 bi Mammae 6. 



Ci Plantar tubercles 6 (Fig. 163). 



di Ears dusky or dusky edged with white. 

 ei Hind foot less than 25 mm. long, 

 fi Tail shorter than head and trunk, 

 gi Size very small; length 120-130 

 mm. 



hi In Florida and Georgia P. polionotus. 



h.2 In Texas P. nianiculatus pallescens. 



g2 Length over 130 mm. 



hi Tail very sharply bicolor. . . .P. maniciilatus. 

 h2 Tail not sharply bicolor. 



ii In the southern States P. gossypinus. 



\2 In the central and eastern 



States P. leucopus. 



fa Tail equal to or longer than head and 

 trunk, 

 gi Ears large, being 18-25 mm. from 



notch P. truei. 



g2 Ears 18 or less from notch. 



hi Hind foot 23 mm. or more long, 

 ii Tail usually less than 90 

 mm. long, 

 ji In the southern States. P. gossypinus. 

 J2 Eastern and central 



States P. leucopus. 



ii TaU more than 90 mm. long.P. hoylei. 

 hi Hind foot under 23 mm. long, 

 ii Tail about the length of 

 head and trunk. 



ji Tail sharply bicolor P, maniculatus 



J2 TaU not sharply bicolor. 

 ki In the southern 



States P. gossypinus. 



k2 Eastern and central 



States P. leucopus. 



\i Tail longer than head and 

 trunk, 

 ji Tarsal joints white. . . .P. pectoralis. 

 J2 Tarsal joints dusky, 

 ki Proximal half of 



foot hairy P. maniculatus. 



