REVISION OF THE JUMPING MICE OF THE GENUS ZAPUS. 25 



Color. Type in summer pelage: Sides ochraceous-buff, moderately 

 lined with black-tipped hairs; back slightly darker, thickly flecked 

 with black; tail not sharply bicolored; beneath, dull white; feet soiled 

 white. 



Cranial characters. Skull massive; brain case high and broad; 

 zygomata rather short; palate broad and long; interpterygoid fossa 

 broad and shallow, with bordering edge of palate much excavated. 

 Maxillary portion of zygomata heavy and nearly perpendicular to main 

 axis of skull; incisive foramina large and elliptical. The skull of Z. 

 major differs from those of Z. trinotatns taken near type locality and from 

 northern Washington, as follows: Rostrum larger and nasals broader; 

 brain case higher; ascending portion of jugal steeper. 



Measurements. Type: Total length, 255; tail vertebra?, 155; hind 

 foot, 35. Skull (type): Basilar length, 20.4; zygomatic breadth, 13; 

 mastoid breadth, 11.2; iuterorbital constriction, 4.7; incisor to post- 

 palatal notch, 10; foramen magnum to postpalatal notch, 8.6; fronto- 

 palatal depth at middle of molar series, G.5. 



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

 men from the Warner Mountains, in southern Oregon. The skull bears 

 some resemblance, especially in the form of the brain case, to those ot 

 Z. trinotatus and its subspecies alien! . It is apparently shut off by 

 natural barriers from all of the forms surrounding it, with the possible 

 exception of Z. montanus, and has no close affinities with them. From 

 Z. montanus it differs to such an extent that intergradation is out of the 

 question. 



Specimens examined. The type. 



ZAPUS NEVADENSIS sp. nov. Nevada Jumping Mouse. 



Type from Ruby Mountains, Nevada, No. 94185, 9 ad., U. S. Nat. Museum, Biological 

 Survey Coll. Collected June 21, 1808, !>y Vernou Bailey. Original No. 6581. 



Geographic distribution. Known only from type locality. 



General characters. Size rather large; color light; molar series long 

 and rather narrow. 



Color. Dorsal area about as in Z. princeps, pale yellowish-brown, 

 profusely mixed with .black-tipped hairs; sides light ochraceous-buff, 

 becoming almost white on cheeks, moderately lined with black-tipped 

 hairs, the basal portion of fur cinereous, noticeably lighter in color than 

 in Z. princeps, with a few white hairs intermixed; beneath, pure white. 



Cranial characters. The skull of the type and only known specimen 

 is large, but rather lightly bnilt. Compared with skulls of Z. pri turps 

 from Colorado it is smaller and natter; brain case shorter and more 

 rounded; incisive foramina smalt and elliptical; bullre smaller; molars 

 rather narrow, but molar series long; zygomata short and not broadly 

 spreading. Compared with skulls of Z. trinotatus alleni from the Sierra 

 Nevada, Calif., it differs as follows: Smaller, but with molar series 

 longer; incisive foramina smaller and narrower posteriorly; zygomata 



