REVISION OF THE JUMPING MICE OF THE GENUS ZAPUS. 31 



Color. " Dorsal area not sharply defined, but so strongly suffused with 

 yellowish that the yellow predominates over the black; sides butty- 

 yellow, moderately lined with black hairs; inner side of legs only 

 slightly darkened; tail sharply bicolor; grayish above, white beneath; 

 lore and hind feet soiled white." ! A topotype, younger than the type 

 from which the above description was taken, "has the dorsal area even 

 less distinct, the entire upper parts being ochraceous yellow." 



Cranial characters. Compared with that of Z. montanus (its nearest 

 relative geographically) the skull of Z. pacificus is smaller; the rostrum 

 and nasals shorter; audital bulhe smaller; basi-occipital broader between 

 bulht; interpterygoid fossa shorter; upper molar series more divaricat- 

 ing posteriorly. 



Measurements. The type measures: Total length, 225; tail vertebrte, 

 141; hind foot, 31. Skull: Basilar length, 17.5; zygoinatic breadth, 

 12; mastoid breadth, 10; interorbital constriction, 4.5; incisor to post- 

 palatal notch, 8.4; foramen magnum to postpalatal notch, 7.2; fronto- 

 palatal depth at middle of molar series, 6. 



General remarks. Owing to the small number of specimens available 

 from the immediate region, it is impossible to discuss satisfactorily the 

 true relationship of Zapus pacificus to the surrounding species. The type 

 and a topotype taken at the same time are in a peculiar washed-out, 

 almost albinistic, pelage, and may possibly be abnormal, especially as 

 the locality is well within the humid, heavily forested area, where most 

 of the animals are darker in color than their congeners to the eastward. 

 The species, however, has fairly well marked skull characters and is 

 undoubtedly a good form. An immature specimen from Siskiyou, Oreg., 

 taken September 28, doubtless referable to this form, has dorsal area 

 more distinct; sides brighter ochraceous and with more black hairs; 

 upper surface of tail darker and fur of upper parts darker at base than 

 specimens from the type locality. Another, from Little Shasta, Calif., 

 taken September 20, also provisionally referred to this form, resembles 

 the Siskiyou specimen, but has dorsal area finely flecked with yellowish 

 instead of ochraceous. 



Specimens examined. Total number, 4, from the following localities: 

 Oregon: Prospect, Rogne River Valley (type locality), 2; Siskiyou, 1 (not 



typical). 

 California: Little Shasta, 1 (not typical). 



ZAPUS SALTATOR Allen. Stickeeu Jumping Mouse. 

 Zapits sallator Allen, Bull. Am. Mus. Nat. Hist., N. Y., XII, p. 3, Mar. 4, 1899. 



Type locality. Telegraph Creek, Northwest Territory, Canada. 



Geographic distribution. Telegraph Creek south to mouth of Skeeua 

 Kiver and Tschimshian Peninsula; limits of range unknown. 



General characters. Similar in early fall pelage to Z. trinotuttui, but 

 smaller and differing in cranial characters. 



1 From origiual description. 



