588 Life-histories of Northern Animals 



resemble Zapus hudsonius in their peculiar style of coloura- 

 tion. Teeth: 



Inc. ; prem. ; mol. = 15 



i-i 0-0 3-3 



The species insignis has no premolars, therefore but 16 

 teeth in all; it is type of the sub-genus Napceozapus. 



SIZE The Hudsonian Jumping-mouse is further distinguished 



by: Total length, about 8^ inches, rarely over 8| (210 mm., 

 rarely over 215 mm.); hind-foot, I5 inches (28 mm.); tail, 

 about 5 inches (127 mm.) — of course this is its most variable 

 proportion, ranging from 4 to 5I inches (102 to 140 mm.). 



The females are smaller; I have found them but 7I inches 

 (184 mm.) in total length. 

 COLOUR The under-fur of all the upper parts is lead colour, over- 



laid on the cheeks and sides with a strong ochre yellow, and 

 on the crown and back with blackish and ochre mixed; all 

 below is pure white. The effect is of a yellow Mouse, with a 

 sharply marked brown band down its back, and a white breast. 



In autumn the back band is less marked and the yellow 

 brighter. 



When seen alive it is easily identified by its yellow colour 

 and extraordinarily long tail, and, if in motion, by its flying leaps. 



The following races are recognized: 



hudsonius Zimm., the typical form. 

 campestris Preble, large and bright-coloured. 

 ladas Bangs, larger and darker, with larger hind-foot. 

 alascensis Merriam, larger and darker, with longer skull. 

 americanus Barton, very small. 



Life-history. 



RANGE The true Zapus hudsonius of Zimmerman, described in 



1780 from a Hudson Bay specimen, is a species widespread in 



