288 On Two Subspecies of the Arctic Fox. 



appai'ent identity of the Spitzbergen foxes with those of 

 Iceland, Novaya Zenilya, and Greenland, since the measure- 

 ments of skulls in the museums of Dundee and Cambridge, 

 for the use of which we are indebted to the kindness of 

 Professor D'Arcy W. Thompson, C.B., and of Mr. S. F. 

 Harmer, show that the Iceland and some of the Greenland 

 foxes belong also to a small race, which we are unable to 

 distinguish from that which inhabits Spitzbergen. In 

 Greenland it is interesting to note that both forms occur; and 

 although the localities which accompany some of the skulls 

 from that country are not as exact as we could wish, there is 

 evidence to show that the ranges of the smaller and larger 

 races meet somewhere in the neighbourhood of Davis Straits, 

 and hence it seems possible that the foxes of the American 

 mainland belong to a large race like that of the mainland 

 of the Old World. This supposition is partly borne out 

 by the presence in the British Museum collection of a large 

 female skull from the Aleutian Islands (no. 91. 12. 18. 3). 

 As, however, it is well known that Arctic foxes have been 

 frequently turned down on the islands of the Aleutian chain, 

 we do not think it advisable to give too much importance to 

 this specimen. 



At all events we have no specimens from the American 

 mainland with which to con)pare our Old- World series, and 

 hence it is only possible, in the present state of our knowledge, 

 to distinguish two races, one ot which — the larger — is found 

 all round the Arctic portions of the Eurcxsian continent and 

 on the Commander Islands, and probably also on the corre- 

 sponding portions of North America, while the smaller race 

 is confined to Spitzbergen, Iceland, and Greenland, meeting 

 the larger race at Davis Straits. 



We are not in a position to give any external differences 

 whereby the two races may be distinguished, as the British 

 Museum does not possess a scries of skins of the Arctic Fox. 

 It is probable, however, that such external differences exist. 



The average total length of the series of skulls of the larger 

 form which we have been able to examine is 134 millim., and 

 of the smaller form only 126 millim., for males, the corre- 

 sponding measurements of the skulls of female animals being 

 124 and 118 millim. respectively; so that the dimensions 

 of males from Spitzbergen overlap those of females of the 

 larger race. 



The largest male skull of C. lagopus typicus{e. coll.G. E. II. 

 B.-H. no. 17) reaches a length of 140 millim., and the 

 smallest (e coll. G. E. H. B.-Il. no. 20) 130-5 millim. ; both 

 are fiom Kamtchatka. The largest Spitzbergen male which 



