ustela_) the dentition is i. 3/3, c. 1/1, p. 4/3, m. 1/2; total 38;
the upper sectorial having its inner lobe close to the anterior edge
of the tooth; and the upper molar being nearly as large as the
sectorial. Lower sectorial with small inner tubercle. Vertebrae: C. 7,
D. 14, L. 6, S. 3, Ca. 18-23. Body long and slender. Limbs short,
partially digitigrade, with the feet rounded and the toes short, with
compressed, acute, semi-retractile claws. Tail moderate or long, more
or less bushy. One species, _M. martes_, the pine-marten, is British;
the remainder inhabit the northern regions of Europe, Asia and
America. Many of the species, as the sable (_M. zibellina_), yield fur
of great value (see MARTEN).

The dentition of _Putorius_ differs from that of _Mustela_ chiefly in
the absence of the anterior premolars of both jaws. The teeth are more
sharply cusped, and the lower sectorial wants the inner tubercle.
External characters generally similar to those of the martens, but the
body longer and more slender, and the limbs even shorter. All the
species are small animals, of active, bloodthirsty and courageous
disposition, living chiefly on birds and small mammals, and rather
terrestrial than arboreal, dwelling among rocks, stones and
out-buildings. Some of the species, as the stoat or ermine (_P.
ermineus_), inhabiting cold climates, undergo a seasonal change of
colour, being brown in summer and white in winter, though the change
does not affect the whole of the fur, the end of the tail remaining
black in all seasons. This is a large genus, having a very extensive
geographical range throughout the Old and New Worlds, and includes the
animals commonly known as weasels, polecats, ferrets and minks (q.v.).

In the glutton (_Gulo luscus_) the dentition is i. 3/3, c. 1/1, p.
4/4, m. 1/2; total 38; the crowns of the teeth being stout, and the
upper molar much smaller than the sectorial. Lower sectorial large,
with small heel and no inner tubercle. The dentition, though really
but a modification of that of the weasels, presents a general
resemblance to that of hyena. Vertebrae: C. 7, D. 15, L. 5, S. 3, Ca.
15. Body and limbs stoutly made; feet large and powerful,
subplantigrade, with large, compressed, much-curved and sharp-pointed
claws. Soles of the feet (except the pads of the toes) covered with
thick bristly hairs. Ears very small, nearly concealed by the fur.