26 NORTH AMERICAN FAUNA. 



shorter and less spreading 5 brain case flatter; rostrum shorter. Com- 

 pared with the skull of the specimen from Mountain City, Nev., doubt- 

 fully referred to Z. oregonus, the type differs as follows : Slightly smaller 

 and younger; zygomata shorter and zygomatic breadth slightly less; 

 shape of brain case not strikingly different; molar series decidedly 

 longer; incisive foramina very much smaller and narrower posteriorly; 

 postpalatal notch indenting palate farther, nearly to middle of posterior 

 molars; bulhe slightly smaller. Mandible slighter, but lower molar 

 series longer. 



Measurements. Type: Total length, 242; tail vertebra, 150; hind 

 foot, 33. Skull (type): Basilar length, 19.4; zygoraatic breadth, 12; 

 mastoid breadth, 11; iuterorbital constriction, 4.6; incisor to postpalatal 

 notch, 9.5; foramen inagnum to postpalatal notch, 8; fron to-palatal 

 depth at middle of molar series, G. 



General remarks. The present form is based on a single adult speci 

 men collected in the liuby Mountains in east-central Nevada. It does 

 not seem to be closely related to any of the forms whose ranges partially 

 surround its habitat. While it is probably most nearly related to Z. 

 princeps, it seems to differ enough to warrant specific separation. 



Specimens examined. The type. 



ZAPUS TRINOTATUS Rhoads. Northwest Jumping Mouse. 

 (Pl.I,flgs.5,5a.) 



Zapua Irinotatus Rhoads, Proc. Acad. Nat. Sci. Phila., 1894, p. 421, Jan. 15, 1895. 



Zapua imperator Elliot, Field Columbian Mus., Pub. 30, Zool. Ser., I, No. 11, p. 228, 



Feb. 1, 1899; ibid, No. 13, pp. 260-261, 1 fig. in text, March, 1899. (Type from 



Sieg's ranch, Elwah Kiver, Clallam County, Wash.) 



Type locality. Lulu Island, mouth of Fraser River, British Columbia. 



Geographic distribution. Coast region of southern British Columbia, 

 Washington (including Cascades), Oregon (west of western base of 

 Cascades), and northern California, south to Huinboldt Bay. 



General characters. Size large; color bright; skull large and broad. 



Color. Summer pelage: Sides dark ochraceous-buff', rather heavily 

 lined with black-tipped hairs; dorsal area very distinct, moderately 

 flecked with color of sides; beneath white, frequently suffused or 

 blotched with fulvous, especially in young; outer surface of forearm 

 and legs dusky; tail quite strongly bicolored, in dried skins dusky 

 brown above and yellowish-white below. In early fall pelage the sides 

 are dull yellowish instead of ochraceous; dorsal area duller than in 

 summer, much more thickly flecked with yellowish hairs. In immature 

 individuals the dorsal area is especially indistinct. 



Cranial characters. Skull large and rather heavily built, about the 

 size of that of Z. princeps. Brain case broader and more globular; 

 zygomatic breadth greater; palate shorter; molars more lightly built 

 than in that species. 



