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The havoc they make is far greater than one would think possible from their 
small size. 
The Polecat slays Babbits and Hares in great number, and ever and anon 
depopulates the farmer's hen-roosts; but its life is not all one of unmixed 
evil, for it frequently confers a great benefit on the country population by 
devouring rats ; in fact ferrets are often specially trained to hunt those 
animals. 
The fur of the Polecat is of but little value, being chiefly used for making- 
paint brushes. 
Mustela erminea, var Americana. (The Stoat, or Ermine Weasel.) In 
speaking of this animal, the author remarked: — 
The distinctive feature of this variety of the common Stoat is the com- 
paratively great length of the tail, which is from one-third to one-half that 
of the body ; whereas in the African and European Stoat, the tail is only 
about a fifth or sixth of the whole length of the creature. 
This Stoat is considerably smaller than our British one, approaching more 
nearly in size to the Weasel ; but although so diminutive in comparison with 
ours, I find on inquiry that it is of the full average size of American Ermines. 
The colour of this animal varies, as of course you are aware, from a deep 
rich brown in summer to a pure creamy white in winter. This change is not 
caused by a dropping off or moulting of the summer coat, but is an actual 
change in the colour of each individual hair. 
The object of this extraordinary change is doubtless twofold, as a means 
of protection against its enemies, by assimilating it to the colour of the snow- 
covered ground, and as a means of protecting it from the intense cold. 
The author then exhibited four specimens of Seals, evidently belonging, 
he said, to three distinct species ; but as he had not had time accurately to 
determine their specific identity, he would reserve an account of them for 
a future occasion. 
Trichechus rosmarus. (The Walrus,) A single canine tooth of this 
animal was shown. Mr. Liepner said : — 
The dental formula of this animal is very peculiar. In the young we find 
three incisors in each inter-maxillary bone, and two on each side of the fore- 
part of the lower jaw. These, however, soon disappear, except the outer pair 
above, which remains close to the inter-maxillary suture, and on the inner 
side of the canines. In the adult, behind the permanent incisors, and much 
resembling them, are three simple molars, and there are four similar teeth on 
