I 74 Bulletin American Museum of Natural History. [Vol. XIX, 



31. Putorius (Arctogale) ermineus (Linn.) 

 ERMINE. 



Represented by 20 adult males and i adult female (skins 

 and skulls) collected by Mr. Buxton in the vicinity of Gichiga, 

 all in the white winter pelage except one. One was taken in 

 January, 6 in April, 2 in October, 5 in November, 6 in De- 

 cember, and i (in summer dress) in August. Besides these 

 there are 10 skins with skulls, brought by Mr. Bogoras from 

 the mouth of the Anadyr River, and 9 specimens in alcohol 

 collected by Mr. Jochelson near Verkhene Kolimsk, on the 

 Kolyma River. 



The length of the black tip to the tail is variable, ranging 

 from 65 mm. to 95, and averaging about 75, or from consider- 

 ably less than half to considerably more than half of the 

 whole length of the tail. The same range of variation is 

 shown by a large series of P. richardsonii from Repulse Bay, 

 Arctic America. These two large series show that the relative 

 length of the black tip to the whole length of the tail is too 

 variable a feature to have much importance in the considera- 

 tion of single specimens from different localities. There is 

 also a wide range of variation in the amount and depth of the 

 yellow suffusing the pelage of the ventral surface, the limbs, 

 and the basal portion of the tail. Some specimens show none, 

 and others merely the slightest tinge, restricted to the limbs and 

 edges of the ventral surface, while in still others the tone 

 of yellow approaches deep chrome and covers the whole ven- 

 tral surface, from the posterior border of the pectoral region 

 to the black portion of the tail, including both fore and hind 

 limbs, the rump, and the basal half of the tail. Several of 

 Mr. Buxton's specimens show no tinge of yellow; nearly all 

 of Mr. Bogoras 's are either wholly without yellow or show 

 only the slightest trace, while some of Mr. Jochelson's are 

 without and some have a very deep shade of yellow. The 

 single specimen in summer pelage has the whole ventral sur- 

 face strongly yellow, including the breast and throat. A 

 series of 14 specimens of P. richardsonii in winter pelage show 

 little or no yellow, while 22 in summer pelage all show more 



