REVISION OF THE JUMPING MICE OF THE GENUS ZAPUS. 21 



does intergrade with true hudsonius in western Minnesota. The dif- 

 erence between summer and early fall pelage is very great, apparently 

 greater than in any other species. 



Specimens examined. Total number, 35, from the following localities: 



Manitoba : Carberry, 2 ; Portage la Prairie, 1 ; Red River settlement, 4 ; Sel- 

 kirk settlement, 1. 



North Dakota : Devils Lake, 1 ; Fort Sisseton, 1 ; Fort Wadswortb, 1 ; Pem- 

 bina, 2. 



Montana : Little Big Horn River, 1. 



South Dakota : Cnster, 4. 



Wyoming: Bear Lodge Mountains (type locality), 6; Cheyenne, 1; Devils 

 Tower, 1 ; Sherman, 1 ; Sundance, 1 



Nebraska : Columbus, 1. 



Colorado : Loveland, 5. 



Missouri : Jackson County, 1. 



ZAPUS TENELLUS Merriam. Kamloops Jumping Mouse. 

 Zapm lenellns Merriam, Proc. Biol. Soc. Wash., XI, p. 103, April 26, 1897. 



Type locality. Kamloops, British Columbia. 



Geographic distribution. Known only from vicinity of type locality. 



General characters. Size rather small; ears rather large; coloration 

 dark. 



Color. Early fall pelage : Somewhat similar to Zapus hudsonius in 

 corresponding pelage but much darker; sides olive yellowish, heavily 

 intermixed with black-tipped hairs; dorsal area somewhat as in hud- 

 sonius, but not well denned, contrasting less with sides; tail sharply 

 bicolor, darker above and at tip than in hudsonius; nose, ears, and 

 outer sides of thigh and forearm dusky, much darker than in hudsonius; 

 fore and hind feet soiled whitish. 



Cranial characters. Skull similar to that of Zapus hudsonius, but 

 less swollen in frontal region; border of ascending portion of jugal 

 straighter; cranium more arched. 



Measurements. Average of four specimens from type locality: Total 

 length, 208; tail vertelme, 128; hind foot, 30.5. Skull: Average of 3 

 skulls from type locality : Basilar length, 1G.5; zygomatic breadth, 10.6; 

 nmstoid breadth, 9.0; interorbital constriction, 4.2; incisor to post- 

 palatal notch, 7.0; foramen magnum to postpalatal notch, 0.9; frouto- 

 palatal depth at middle of molar series, 5.7. 



General remarks. Zapus tenellus is a well-marked form requiring 

 comparison only with Z. hudsonius and its subspecies alascensis. In 

 color it resembles alascensis, but in cranial characters it departs from 

 Jnidisonius in another direction. There is a possibility that it may be 

 found to intergrade with one of them to the northward, but until such 

 intergradation is proved, it seems best to allow it full specific rank. 



Specimens examined. Total number, 7, from the following localities: 

 British Columbia : Ducks, 2; Kamloops, 5. 



