66 MOSTLY MAMMALS 
the ermine (or stoat) are white at all seasons, but this does 
not seem to be authenticated. 
Observations are wanting as to whether the changes of 
coat and colour in the mountain hare bear any relation 
to the appearance and disappearance of snow, or whether 
they occur regularly at the same season of the year. In 
the case of the ermine in the Adirondack region of New 
York, Dr. C. H. Merriam tells us that in this animal the 
white livery is assumed only after the first fall of snow, 
while the resumption of the brown coat does not take 
place till the snow begins to melt. Unfortunately, he 
says nothing in regard to change of coat. The late 
Dr. Coues stated, however, that in the case of the ermine 
the bi-annual change of coat takes place at the same 
season, but that it depends upon the condition of the 
temperature at the time whether the new coat differs in 
colour from its predecessor. In other words, the change 
from brown to white might be due either to shedding the 
coat or to bleaching of the hair subsequent to such 
shedding. The case of the mountain hare is, however, 
strongly suggestive that the colour-change is in all instances 
coincident with the shedding of the coat. 
It is, of course, quite evident that the assumption of a 
white winter livery by mountain hares and ermines living 
in regions where the snow lies on the ground for a con- 
siderable portion of the year is for the purpose of rendering 
such animals as inconspicuous as possible when in their 
native haunts. And, so far as we know, such a change 
is universal among the species named when dwelling in 
high northern latitudes. 
There is, however, another animal inhabiting the North 
Polar regions of both hemispheres in which the change 
to a pure white winter dress is limited to certain indi- 
