MAMMALS OF MINNESOTA. 109 



ation from the white of the lower parts is quite sharp. Only 

 the end of the tail is black. The white of the under parts 

 is suffused with a sulphury tint. The winter pelage is white, 

 unbroken except by the black tip of the tail and the yellow 

 suffusion. The change is a gradual one, and consists of a 

 gradual substitution of white for the darker color, usually by 

 gradual encroachment from below, leaving a constantly nar- 

 rower dorsal band. Sometimes, however, the substitution goes 

 on over the entire dorsal region simultaneously. Dr. Coues 

 considers that the change is effected in either of two ways: 

 Either the renewal of the pelage by the outgrowth of hairs of a 

 different color, or the change of the hairs after their formation, 

 cold being the conditioning circumstance in either case. We 

 may be permitted to doubt that the question is satisfactorily 

 settled. Two important purposes are subserved by the change, 

 the animal is screened from observation and thus protected 

 from its foes and rendered more successful in the chase, and 

 the white color makes the pelage a less perfect conductor of the 

 animal heat. 



The Latin name Puiorius, refers to the odor which is derived 

 .from the secretion of the anal glands, and is only less persist- 

 ent and offensive than in the skunk. 



The always pleasing pen of Mr. Wm. MacGillivray has fur- 

 nished us with the following general account of the habits of 

 the Stoat as observed in Great Britain: "It appears that in 

 England generally the Ermine is less common than the Wea- 

 sel; but in Scotland, even to the south of the Frith of Forth, it 

 is certainly of more frequent occurrence than that species; and 

 for one Weasel I have seen at least five or six Ermines. It 

 frequents stony places and thickets, among which it finds a 

 secure retreat, as its agility enables it to outstrip even a dog 

 in a short race, and the slimness of its body allows it to enter 

 a very small aperture. Patches of furze, in particular, afford 

 it perfect security, and it sometimes takes possession of a 

 rabbit's burrow. It preys on game and other birds, from the 

 grouse and ptarmigan downwards, sometimes attacks poultry 

 or sucks their eggs, and is a determined enemy to rats and 

 moles. Young rabbits and hares frequently become victims to 

 its rapacity, and even full grown individuals are sometimes 

 destroyed by it. Although in general it does not appear to 

 hunt by scent, yet it has been seen to trace its prey like a dog, 

 following its track with certainty. Its motions are elegant, 

 and its appearance extremely animated. It moves by leaping 



