28 NORTH AMERICAN FAUNA. 



General characters. Similar to Z. trinotatus; differing slightly in 

 external anil cranial characters. 



Color. Early summer pelage: Sides rather pale ochraceous-buff, 

 only moderately lined with black-tipped hairs ; dark dorsal area well 

 defined, rather lighter than in Z. trinotatus; under parts pure white; 

 never marked with fulvous, except that rarely young specimens are 

 slightly suffused with this color beneath; tail in dried skins rather 

 light grayish-brown above and yellowish- white below; tail lighter 

 toward tip, the pencil often white. Compared with Z. trinotatus, adults 

 of this species have dorsal area less necked with color of sides and fewer 

 black-tipped hairs on sides. Upper surface of tail, ears, head, and 

 outer surface of thighs lighter than in Z. trinotatus. Immature indi- 

 viduals in late summer pelage have dorsal area very indistinct and 

 much mixed with ochraceous. Fall pelage: An adult taken at Cassel, 

 Calif., August 29 (very fat and doubtless about to hibernate), is in a 

 pelage quite similar to that worn in early summer, but the sides are 

 lighter ochraceous, especially anteriorly, and the dorsal area is more 

 thickly necked with color of sides. Z. alleni apparently does not assume 

 the dull yellowish fall pelage of Z. trinotatus. 



Cranial characters. Skulls similar to those of Z. trinotatus, but 

 smaller, with much smaller bulhe. From that of Z. montanus of the 

 Cascade Range the skull of the present species differs so much as not to 

 require comparison. 



Measurements. Eight adults from Emerald Bay, Lake Tahoe, aver- 

 age: Total length, 234.6; tail vertebrae, 143.6; hind foot, 32.5. Two 

 adults from Mount Shasta, Calif., a-verage: Total length, 249.5; tail 

 vertebrae, 152.5; hind foot, 32.5. Skull: Eight skulls from Emerald 

 Bay, Lake Tahoe, average: Basilar length, 39.7; zygomatic breadth, 

 12.6; mastoid breadth, 10.5; interorbital constriction, 4.5; incisor to 

 postpalatal notch, 9.3; foramen magnum to postpalatal notch, 8.2; 

 fronto- palatal depth at middle of molar series, 6.5. 



General remarks. Zapus t. alleni is a fairly well-marked subspecies 

 occupying the Sierra Nevada of California, from Mount Shasta south 

 to the region about the head of the North Fork of Kern Eiver. It is 

 a very beautiful species and differs from all others of this subgenus in 

 often having the pencil, and occasionally more of the tail, white. 



Specimens examined. Total number, 61, from the following localities: 



California: Big Trees, 1; Cassel, 1; East Fork Kaweah River, 2; Emerald 

 Bay, Lake Tahoe, 19; Kern River (North Fork 'Kern Lakes'), 1; Lasseii 

 Peak, 14; Mammoth, 1 ; Monnt Shasta, 20; Summit, 1 ; Upper Bear Creek. 1. 



ZAPUS MONTANUS (Merriam). Mountain Jumping Mouse. 

 Zapus Irlnotatus montanus Merriam, Proc. Bio]. Soc. Wash., XI, p. 104, April 26, 1897. 



Type locality. Crater Lake, Mount Mazama, Oregon. 

 Geographic distribution. Cascade Kange in Oregon. 

 General characters. Smaller and duller in color than Z. trinotatus; 

 also differing in cranial characters. 



