Page 113 - My FlipBook

OF THE GRINDERS. 97

it ig
The third Grinder is commonly called Dens Sapientice ;
a little shorter and smaller than the others, and inclined a little
more inwards and forwards. Its body is nearly of the same
cusps, and a broad posterior talon. The third molar is very small.
—
Professor Owen remarks "The succession of two tubercular teeth
behind the permanent sectorial tooth in the adult, or permanent
dentition of the lower jaw, carries the genus Cams farther from the type
of its order, and stamps it with its own proper omnivorous character,
and this contributes to adapt the Dog to a greater variety of climates
and food, and of other circumstances, all of which tend, in an important
degree, to fit that animal for the performance of its valuable services to
Man." In the Weasel tribe (Mustelldce) there are usually three pre-
molars in the upper jaw on each side ; the Otter, however, has four.
In the lower jaw on each side there are four or three premolars. The
true molars are usually $'. £: . In the Otter the sectorial and molar teeth
present increased grinding surfaces, in relation to the coarser nature of
their anim al diet, and the necessity of crushing the bones of fish
before they are swallowed. In the great Sea-Otter (Enhydra) the upper
sectorial (p. 4) is remarkably modified ; the two lobes of the blade are
hemispheric tubercles. The last tooth (m. 1) is larger than the sectorial,
and has a similar broad crushing form. The crown of the lower sectorial
(m. 1) presents many gradations in this genus from the cutting form
observed in the Weasel and Glutton, to the crushing type of the Eatel
and Sea-Otter. In a South American Skunk, the second upper premolar is
absent. , in the subfamily of Badgers
The molar series, p. £ \ f ; , m. | ] |;
(Melidce) contrasts in its tuberculate and omnivorous character with the
sectorial type found in the predaceous Weasel. The upper true molar
in the European Badger attains an enormous size as compared with that
of the same tooth in any of the preceding Carnivora ; it presents three
external tubercles, and an extensive horizontal surface traversed by a low
ridge, and bounded by an internal belt. The molar series in the Bears
(Ursidoe) is p. || £ ire. |; £.'
, ; but the number of premolars presents
some variation in different species. The true molars in both jaws present
a tuberculate grinding surface. The teeth which correspond with the
true molars in the Seals (Phocidce) are more numerous than in the
digitigrade family of Carnivores ; in the upper jaw, they occasionally
rise to the typical number of three on each side. The entire molar
series in the Seals is usually five or six teeth on either side of the upper
jaw, and five on each side of the lower. In some genera—as the Eared
Seals (Otarice), and Elephant Seals (Cystophora), they are each supported
by a single fang, in other genera by two fangs, which are usually connate
in the first or second teeth. The fangs of all the teeth in the Seals are
of remarkable thickness. The crowns of the molars are generally
compressed, conical, and pointed ' cingulum,' and
; they present the