The third and last family of the Pinnipedia, and thus of existing
Carnivora, is the _Otariidae_, which includes the eared seals, or
sea-lions and sea-bears. In all these animals, when on land, the
hind-feet are turned forwards under the body, and aid in supporting
and moving the trunk as in ordinary quadrupeds. There are small
external ears. Testes suspended in a distinct external scrotum. Skull
with post-orbital processes and alisphenoid canal. Soles of feet
naked. By many naturalists these seals are arranged in a number of
generic groups, but as the differences between them are not very
great, they may all be included in the typical genus _Otaria_. The
dental formula is i. 3/2, c. 1/1, p. 4/4, m. (1 or 2)/1; total 34 or
36. The first and second upper incisors are small, with the summits of
their crowns divided by deep transverse grooves into an anterior and a
posterior cusp of nearly equal height; the third large and
canine-like. Canines large, conical, pointed, recurved. Molars and
premolars usually 5/5, of which the second, third and fourth are
preceded by milk-teeth shed a few days after birth; sometimes (as in
fig. 7) a sixth upper molar (occasionally developed on one side and
not the other); all with similar characters, generally single-rooted;
crown moderate, compressed, pointed, with a single principal cusp, and
sometimes a cingulum, and more or less developed anterior and
posterior accessory cusps. Vertebrae: C. 7, D. 15, L. 5, S. 4, Ca.
9-10. Head rounded. Eyes large; ears small, narrow and pointed. Neck
long. Skin of the feet extended far beyond the nails and ends of the
digits, with a deeply-lobed margin. The nails small and often quite
rudimentary, especially those of the first and fifth toes of both
feet; the best-developed and most constant being the three middle
claws of the hind-foot, which are elongated, compressed and curved.
Sea-bears and sea-lions are widely distributed, especially in the
temperate regions of both hemispheres, though absent from the coasts
of the North Atlantic. They spend more of their time on shore, and
range inland to greater distances than the true seals, especially at
the breeding-time, though they are obliged to return to the water to
seek their food. They are gregarious and polygamous, and the males
usually much larger than the females. Some possess, in addition to the
stiff, close, hairy covering common to the group, a fine, dense,
woolly under-fur. The skins of these, when dressed and deprived of
the longer harsh outer hairs, constitute the "sealskin" of commerce.
The species include _O. stelleri_, the northern sea-lion, the largest
of the genus, from the North Pacific, about 10 ft. in length; _O.
jubata_, the southern sea-lion, from the Falkland Islands and
Patagonia; _O. californiana_, from California; _O. ursina_, the
sea-bear or fur-seal of the North Pacific, the skins of which are
imported in immense numbers from the Pribiloff Islands; _O.
antarctica_ or _pusilla_, from the Cape of Good Hope; and _O.
forsteri_, from Australia and various islands in the southern
hemisphere. (See SEAL-FISHERIES.)
Little is known as to the past history of the sea-lions and sea-bears,
but a skull has been obtained from the Miocene strata of Oregon, which
Mr F.W. True states to be considerably larger than any existing
sea-lion skull; its basal length when entire being probably about 20
in. The name _Pontoleon magnus_ has been proposed for this fossil
sea-lion, as the character of the skull and teeth do not agree
precisely with those of any living member of the group. If, however,
all the modern eared seals are included in the genus _Otaria_, there
is apparently no reason to exclude the fossil species.