18 NORTH AMERICAN FAUNA. 



Tail quite sharply bicolored, dusky above and whitish beneath; ears 

 usually edged with ochraceous (whitish iu Inidsonius). Feet white. 

 Fall pelage: Dorsal area usually even less distinct than in summer, with 

 the general tinge of entire upper parts yellowish instead of ochraceous. 



Cranial characters. Skull longer than that of typical hwdsoniiis; 

 zygomata considerably longer; zygomatic breadth about the same ns 

 in largest skulls of hudsonius; interorbital constriction slightly wider; 

 brain case higher and averaging slightly longer; rostrum and nasals 

 longer; bullre considerably larger; molar series averaging slightly 

 longer. 



Measurements. Type No. 4169 9 ad., collection of E. A. and O. 

 Bangs: Total length, 238; tail vertebrae, 153; hind foot, 32. Average 

 of five adults from Black Bay, Labrador: Total length, 228; tail verte- 

 brae, 142; hind foot, 32. Skull: Average of four adults from Black 

 Bay, Labrador : Basilar length, 18.8; zygomatic breadth, 11.4; mastoid 

 breadth, 10.2; interorbital constriction, 4.5; incisor to postpalatal 

 notch, 8.9; foramen magnum to postpalatal notch, 8.5; fron to-palatal 

 depth at middle of molar series, 6.3. 



General remarks. Zapus h. ladas is a fairly well-marked subspecies 

 represented by 23 specimens in the collection of E, A. and O. Bangs, 

 and 5 in the Biological Survey collection. The best characters separat- 

 ing this form from typical hudsonius, as here restricted, are the longer 

 tail, larger hind foot, and longer skull, with larger audital bulhe. 

 This latter character is very evident, even iu young skulls. 



Specimens examined. Total number, 28, from the following localities : 



Labrador: Hamilton Inlet (type locality), 3; Black Bay, 20. 

 Quebec: Godbout, 5. 



ZAPUS HUDSONIUS ALASCENSIS Merriam. Alaska Jumping Mouse. 

 Zapus Inidsonins alascensis Merriam, Proc. Biol. Soc. Wash., XI, p. 223, 1897. 



Type locality. Yakutat, Alaska. 



Geographic distribution. Yakutat Bay, north to Yukon Eiver; limits 

 of range unknown. 



General characters. Similar to Zapus hudsonius, but slightly larger 

 and darker. 



Color. Sides dull, dark ochraceous, with many black-tipped hairs; 

 dorsal area quite distinct, but thickly necked with brownish; beneath 

 pure white; tail rather sharply bicolor. 



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

 slightly longer and narrower; zygomata less bowed outward and 

 slightly longer; brain case narrower; molar series longer; crown of 

 last lower molar longer. 



Measurements. Average of four specimens from type locality: Total 

 length, 218; tail vertebra?, 132; hind foot, 31.5. Sknll: Average of 

 two adults from type locality: Basilar length, 18.2; zygomatic breadth, 



