MUSEUM OF COMPARATIVE ZOOLOGY. 159 



The varieties called " Silver Fox," " Black Fox," and " Cross Fox," 

 are taken at long intervals. 



These so-called varieties, to which have been given such distinctive 

 names as Canis deewsatus, C. argentatus, C. /ulcus var. decussatus, etc., 

 etc., and which some authors have regarded as species and the majority 

 as permanent " varieties," are but different degrees of melanism of 

 the common red fox, as they sometimes all occur in the same litter of 

 young.* They appear exactly parallel to the dusky and black varieties 

 of marmots, which are usually considered as only variations of this char- 

 acter. The dusky of the preceding species (C. lupus Linn.) and the 

 black form of several species of Sciurus are probably but the result of the 

 same tendency more highly developed. Foxes in other countries, and 

 particularly the European, are well known to present corresponding dusky 

 and black variations, which have likewise been described as permanent 

 varieties, and even as species. 



Respecting the identity of the red fox of Xorth America with that of 

 Europe there is a diversity of opinion. Most of the old authors consid- 

 ered them specifically the same, while later they were almost as generally 

 regarded as distinct. Recently their identity has been maintained by 

 several high authorities in Europe, among whom are Giebel, Wagner, 

 and Maximilian, and not without a fair show of reason. Professor 

 Baird observes, that careful comparisons of the two show " appre- 

 ciable differences, although the resemblance is very close in external ap- 

 pearances, and scarcely to be expressed except comparatively."! The 



* Audubon and Bachman, in their account of the Cross Fox (" Vulpes f ulcus Desm., 

 var. decussatus Pennant"), in Quadrupeds of North America (Vol. I, pp. 52,53), inci- 

 dentally relate the following: " In the spring we induced one of our servants to dig for 

 the young foxes that had been seen at the burrow which was known to be frequented by 

 the Cross Fox. With an immense deal of labor and fatigue the young were dug out 

 from the side of a hill; there were seven. Unfortunately, we were obliged to leave 

 home, and did not return until after they had been given away and were distributed about 

 the neighborhood. Three were said to have been black, the rest were red. The blackest of 

 the young whelps was retained for us, and we frequently saw, at the house of a neighbor, 

 another of the litter that was red, and differed in no respect from the common Red Fox. 

 The older our little pet became the less it grew like the Black, and more like the Cross 

 Fox. It was, very much to our regret, killed by a dog when about six months old, and, 

 as far as we can now recollect, was nearly of the same color as the specimen figured in 

 our work." 



In the following autumn the female was killed: "It was nearly jet black, with the tip of 

 the tail white. This was the female that produced the young we have just spoken of; 

 and as some of them, as we have already said, were Cross Foxes and others Red Foxes, 

 this has settled the question in our minds that both the Cross Fox and Black Fox are 

 mere varieties of the Red." 



t Mamm. of N.Am., p. 126. 



