e penial bone is cylindrical. As distinctive
characteristics of the _Ursidae_, may be mentioned the presence of an
alisphenoid canal on the base of the skull; the general absence of a
perforation on the inner side of the lower end of the humerus; the
presence of two pairs of upper and three of lower molars, which are
mostly elongated and low-cusped; and the non-cutting character and
fore-and-aft shortening of the upper sectorial, which has no inner
root and one inner cusp (fig. I, III.). Anal glands are apparently
wanting. The short tail, bulky build, completely plantigrade feet and
clumsy gait are features eminently characteristic of the bears.

The great majority of existing bears may be included in the typical
genus _Ursus_, of which, in this wide sense, the leading
characteristics will be as follows. The dentition is i. 3/3, c. 1/1,
p. 4/4, m. 2/3 = 42; but the three anterior premolars, above and
below, are one-rooted, rudimentary and frequently wanting. Usually the
first (placed close to the canine) is present, and after a
considerable interval the third, which is situated close to the other
teeth of the cheek-series. The fourth (upper sectorial) differs
essentially from the corresponding tooth of other Carnivora in that
the inner lobe is not supported by a distinct root; its sectorial
characters being very slightly marked. The crowns of both true molars
are longer than broad, with flattened, tuberculated, grinding
surfaces; the second having a large backward prolongation or heel. The
lower sectorial has a small and indistinct blade and greatly developed
tubercular heel; the second molar is of about the same length, but
with a broader and more flattened tubercular crown; while the third is
smaller. The milk-teeth are comparatively small, and shed at an early
age. The skull is more or less elongated, with the orbits small and
incomplete behind, and the palate prolonged considerably behind the
last molar. Vertebrae: C. 7, D. 14, L. 6, S. 5, Ca. 8-10. Body heavy.
Feet broad, completely plantigrade; the five toes on each well
developed, and armed with long compressed and moderately curved,
non-retractile claws, the soles being generally naked. Tail very
short. Ears moderate, erect, rounded, hairy. Fur generally long, soft
and shaggy.

Bears are animals of considerable bulk, and include among them the
largest members of the order. Though the specie