asel family, and feeds almost entirely upon
fish. Range: This and related varieties over Northern and Eastern North
America. From Group in American Museum of Natural History.]

In the United States the lowest or most primitive mammal is the Opossum.
The baby Opossums--from six to a dozen of them--are born when very small
and undeveloped and are immediately placed by the mother in an
external pouch, where they continue to grow until they are too large to
get into their mother's pocket; then they frequently ride upon their
mother's back, clinging to her fur with their finger-like toes and
wrapping their tails about their mother's tail. The Opossum is the only
animal in this country the young of which are carried around in the
mother's pocket, and the only one which has a prehensile tail; that is,
one used for coiling around and clinging to branches, and the like. Its
food is various, consisting of both animal and plant material--insects,
young birds, pawpaws, persimmons, etc. In the food devoured the Opossum
probably does more good than harm.

[Illustration: NEW YORK WEASEL IN WINTER

A blood-thirsty cousin of the Otter and the Mink. Range: This and
related species found all over United States and Canada. Group in
American Museum of Natural History.]

[Illustration: RACCOON AT ENTRANCE TO ITS DEN IN A HOLLOW TREE

A near relative of the bears. Note the black face-mark and the ringed
tail. Range: This or a related variety occurs in all parts of United
States. Photograph from American Museum of Natural History.]

In their food habits many mammals are decidedly injurious. Rats,
Weasels, Minks, and Foxes destroy poultry; Wolves and Pumas kill
domestic and game animals; Woodchucks or Groundhogs eat clover and
various garden plants; Moles damage the lawns; Rats, Mice, and Gophers
spoil and devour grain; Mice and Rabbits girdle fruit trees, thus
killing them.

On the other hand, many mammals furnish food; _e. g._, Rabbits, Elk, and
Deer. This was more important in pioneer times than at present. Many
furnish furs used as articles of clothing; _e. g._, Raccoon, Fox,
Muskrat, Mink, Otter, Marten, Mole, New York Weasel and other northern
weasels in their winter coats.

[Illustration: POLAR BEAR

An expert swimmer. Feeds upon seals, fish and other animal food. Range:
Arctic regions of the world. Habitat Group in American Museum of Natural
History.]

Many furs are usually sold under trade names that are entirely different