313 



With these general remarks, we will pass now to a more special exam- 

 ination of geographical variation in size in several of the more common 

 species of the North American Fera\ based on the abundant material 

 m the National Museum. 



CANIS LUPUS. 



The common Gray Wolf of the northern hemisphere presents a range 

 of individual variation in color exceeded by but few known species of 

 Mammals ; gray, white, and black individuals, with various intermediate 

 stages of coloration, occurring with greater or less frequency wherever 

 the species abounds, several of these varieties sometimes occurring in 

 the same litter. Black and white wolves seem to occur more frequently 

 at some localities than others, but gray is generally nearly everywhere 

 the prevailing color. Cream-colored and rufous varieties are also said 

 to have a wide prevalence over some parts of the great plains of the 

 interior. To what extent these variations in color are to be considered 

 as geographic is not yet well established.* With such an evident tend- 

 ency to variability, it is not surprising that geographical variation in 

 size is displayed in this species to a marked degree. The variation in 

 this respect constitutes a pretty uniform decrease in size southward, as 

 shown (see the subjoined table) by the size of the skull, only fully 

 adult skulls being here taken. The largest are from Fort Simpson and 

 other localities in or near the Mackenzie River district, six of which, 

 out of a series of nine specimens, exceed 10.25 inches in length (one 

 reaching 11.50 !), and the other three average above 9.50, the whole aver- 

 aging 10.38. The next in size are from the region about Puget Sound, 

 a series of three (the only ones in the collection), averaging nearly 

 10.50. Of sixteen specimens from Forts Benton, Union, and Kandall, 

 on the Upper Missouri, the average is 9.45, the extremes being 10.50 

 and 8.50. Nine specimens frofti Forts Kearney and Harker (chiefly 

 from Fort Kearney, and all pretty old) average a little larger than the 

 Upper Missouri specimens, the extremes being 10.15 and 9.35. A single 

 specimen from the mountains of New Mexico reaches 10.00, while the 

 three most southern (from the Eio Grande and Sonora, Mexico) average 

 only 8.37, being the smallest of the whole series, and averaging 2.00 

 shorter than the series of nine from the Mackenzie Eiver region. This 

 difference is fully 25 per cent, of the average size of a series of upward 

 of eighty specimens ; while the difference between the smallest (from 

 Saltillo, Mexico) and the largest (fropi Fort Simpson) is 3.75, or nearly 

 40 per cent, of the average size of the whole series ! 



* See furtlier on color variatiou iu this species, Bull. Mus. Coinp. ZooL,'Vol. i. pp. 

 154-158. 



