MAMMALS. 



241 



At Saiut Micbaels, among the tbousauds of skins brought in each year, not over one Bhie Fox 

 was observed among every fifteen or twenty White Foxes, and the proportion was sometimes less. 

 I afterwards found this proportion to hold good for the skins seen among the Eskimo of the Bering 

 straits islands and the Alaskan and Siberian Arctic coast in the vicinity of the Straits. Further to 

 the north the Blue Fox becomes more and more scarce. The habits of the two forms are identical. 



From the foregoing it appears that at the southern extreme of their range in Alaska, on the 

 peninsula of Aliaska, perhaps, and certainly on the Aleutian and Fur Seal Islands, the Blue Fox 

 entirely replaces its white relative, and that as we pass farther north the number of blue individ- 

 uals decreases steadily, and the white form becomes more numerous proportionally, until near the 

 northern limit of the mainland the Blue Fox is almost entirely replaced by the white form. The color 

 of the White Fox for several months after it is born is very similar to that of the adult Blue Fox, 

 and the summer fur of the adult White Fox is very similar to the adult Blue Fox's normal pelage. 



Taking these various points into consideration it appears very probable that the White Fox 

 is a special variety of a species originally made up entirely of blue individuals. Peculiar climatic 

 surroundings (which still exist) have impressed the change upon by far the greater part of the 

 individuals now representing the species. This being the case we find upon the Aleutian and Fur 

 Seal Islands at present the most typical representatives of the species, since there only do we find 

 the blue form in its purity. 



VuLPES FULVUS PULTUS (Desmarcst). Eed Fox (Esk. Kdbvtuk). 



List of S2)eciine»s. 

 SKINS. 



