JUNE, 1896.] SYNOPSIS OF THE WEASELS OF NORTH AMERICA. 



23 



collected by E. AV. Nelson. Specimens from the northern Rocky 

 Mountain region (St. Mary Lake, Montana, and Salmon River and 

 1'ahsimeroi Mountains, Idaho) differ in color from the typical animal 

 from Arizona and Colorado, and agree with alleni from the Black Hills 

 in having the upper parts strongly suffused with golden brown, the 

 yellow of the under parts yellow rather than ochraceous, and the under 

 side of the tail strongly yellow on the basal half or two-thirds. The 

 skulls, however, lack the flattened audital bulla? of alleni. Specimens 

 from the Sierra Nevada in California are hardly distinguishable from 

 the Rocky Mountain animal. The only apparent external differences 

 are that the yellow of the under parts reaches up farther under the 

 chin, the white of the upper lip is less extensive, and the under side of 

 the tail is more suffused with yellowish. But none of these characters is 

 constant. In one specimen from Donner, Calif. (No. 2G50, female, Mer- 

 riam Coll.), even the white upper lip is as marked as in Rocky Mountain 

 specimens; it reaches all the 

 way round, fills the space under 

 the nasal pad to the nostrils, 

 and broadens strongly under 

 the eyes. In cranial charac- 

 ters also the differences are 

 slight and inconstant. The 

 postorbital processes are longer 

 and more slender, often becom- 

 ing peg-like in old males. The 

 audital bulhe average smaller 

 and more convex anteriorly, 

 and in the female are decidedly 



narrower and more Subcylin- FlGS - 13 and U P - arizonensis J ad. Boulder County, 



dric. But in an adult female 



from Fort Klamath, Oreg., the bulhe are nearly as broad as in Rocky 

 Mountain females. The three female skulls I have seen of the Sierra 

 form are decidedly smaller than females from the Rocky Mountains. 



The Sierra specimens show a strong tendency to grade into, or at 

 least toward xanthogenys. In nearly half the specimens examined white 

 hairs are present between the eyes, and in several they are sufficiently 

 numerous to form a conspicuous white spot, though the spot is not 

 large and rectangular as in true xanthogenys. The white cheek spots I 

 have not seen in Sierra specimens, but the brown spots behind the cor- 

 ners of the mouth are sometimes present (as in No. 30G55, male, from 

 Upper Cotton wood Meadows, near Mount Whitney, Calif.). 



A specimen from St. George, Utah, an old female, differs in some 

 respects from typical arizonensis. The skull is small and relatively 

 short, and the shortening is mainly in the palate and rostral part, which 

 measures 2 mm. less than the average of adult females of arizonensis of 



