ALOPEX 319 



above rostrum as in Cants ; teeth moderately heavy and large, 

 the length of carnassial and upper molars together contained 

 about 2^ times in palatal length ; canines and incisors inter- 

 mediate between those of Ganis and Vulpes (see fig. 65) ; external 

 form fox-like, but ear short and rounded, not conspicuously 

 overtopping the surrounding fur. 



Remarks. — Although in most respects intermediate between 

 Cams and Vulpes the Arctic foxes form such a natural and 

 circumscribed group that it seems desirable to set them apart as 

 a distinct genus.* Half a dozen species have been described, two 

 of which come within the scope of the present work. 



KEY TO THE EUROPEAN SPECIES OF ALOPEX. 



Condylobasal length of skull about 130 in males, 



121 in females (Scandinavia and Finland)... A. Icujopus, p. 319. 

 Condylobasal length of skull about 120 in males, 



114 in females (Spitzbergeu) A. spitzbcrgcncnsis, p. 324. 



ALOPEX LAGOPUS Linna3US. 



1758. [Canis] lagopus Linnaeus, Syst. Nat., i, 10th cd., p. 40 (Lapland). 

 1816. V[ul2}es] arctica Oken, Lehrb. d. Naturgesch., iii, pt. 2, p. 1033 



(Renaming of Canis lagopus). 

 1820. C[_anis] vulpes cxrulca Nilsson, Skand. Fauna, i, p. 88 (Lajjland). 

 1827. [Canis lagopus] & argentcus Billberg, Synopsis Faunaj Scaudinavise, 



p. 14 (Lapland). 

 1910. Vulpes lagopiis Trouessart, Fauue IMamm. d'Europe, p. 96. 



Type locality. — Lapland. 



Geographical distribution. — Arctic portions of the mainland 

 of Europe and Asia ; in Europe south along the mountains of 

 Scandinavia to south-western Norway, and as an occasional 

 visitant as far as southern Sweden. 



Diagnosis. — General characters as in the genus ; condylobasal 

 length of skull about 130 mm. in males, about 124 mm. in 

 females. 



External cliaracters. — In general external characters Alopex 

 lagopus resembles Vulpes vulpes, though the muzzle is less 

 elongated, and the low, rounded ears (not extending to eye when 

 laid forward) impart a somewhat un-fox-like appearance to the 

 head. Fur very dense, the uuderfur in summer about 12 mm. 

 deep on back, nearly twice as deep and somewhat looser in 

 texture on sides (in winter longer throughout) ; longer hairs 

 rather sparse, not concealing underfur. Tail bushy, with 

 abundant underfur. Feet as in Canis, but claws longer and 

 more slender, and entire palm and sole covered with a dense 

 woolly growth of hair, 15-17 mm. deep in winter, shorter in 



* See Collett, Norges Pattedyr, p. 275, 1911, for account of apparently 

 complete sterility of Arctic fox male with Red fox female, a fact which 

 indicates a fundamental physiological difference between the two animals. 



