58 Frerp Museum or Naturat History — Zodroey, Vor. XI. 
Family CASTORID&-. Beavers. 
Tail broad and flat (paddle shaped), hairless and covered with scales; 
hind feet broadly webbed; skull stout; incisors noticeably large and 
strong. The general character of the skull is sciurine, but postorbital 
processes are absent and the infraorbital foramen is nearly concealed 
by a large nearly vertical ridge of the maxilla; the auditory meatus is 
Skull of a Beaver. (About 34 nat. size.) 
long and tubular and extends upward above level of the zygoma; 
lower leg bones separate; five toes on both fore and hind feet; second 
toe of hind foot with double or divided claw. 
The family consists of but one genus, Castor, represented in North 
America by one species and five geographical races. They are large, 
aquatic Rodents, the largest living representatives of the order in North 
America, often weighing 40 or 50 pounds, and are much hunted and 
trapped for their skins, which are one of the best known commercial 
furs. The anal glands of the Beaver contain a strong scented, oily 
fluid known as ‘‘Castoreum,” which is much used by trappers as a bait 
to attract the animal. It is also used more or less in the manufacture 
of perfumes, and is claimed to possess medicinal properties. 
The only other living representative of this family is the European 
Beaver (C. fiber), which is very similar to our species; it differs in being 
somewhat smaller, the skull is comparatively lighter, and the nasal 
bones are longer. 
