thicker and more obtuse as well as larger crowns than the first
and second milk-molars which they displace. The lower deciduous
sectorial is succeeded by the fourth premolar, which, as usual,
has a more simple crown than the deciduous tooth which it displaces.
The permanent sectorial has no direct deciduous predecessor
and therefore must he held to be a true molar tooth, according to
the character assigned to those teeth in this work. The absence
of a tuberculate molar in the lower jaw of the immature Dog
brings the character of the deciduous dentition of the genus
Cams much closer to that of the typical members of the Carnivorous
Order, and affords an interesting illustration of the law
that 1 unity of organisation is manifested directly as the proximity
of the animal to the commencement of its development.’(1) The
succession of two tubercular molar teeth behind the permanent
sectorial tooth in the adult or permanent dentition of the lower jaw
carries the genus Canis farther from the type of its Order, and
stamps it with its own proper omnivorous character: and this contributes
to adapt the Dog for a greater variety of climate, food,
and other circumstances, all tending in an important degree to fit
that animal for the performance of its valuable services to man.
In no other genus of Quadruped are the jaws so well or so
variously armed with dental organs: notwithstanding the extent
of the series, the vacancies are only sufficient to allow the interlocking
of the strong canines. These are efficient and formidable
weapons for seizing, slaying, and lacerating a living
prey: the incisors are well adapted by their shape and advanced
position for biting and gnawing : the premolars, and especially
the sectorials, are made for cutting and coarsely dividing the
fibres of animal tissues, and the tuberculate molars are as admirably
adapted for cracking, crushing, and completing the comminution
of the food, whether animal or vegetable.
Amongst the aberrant species of Canidce it is interesting to
find in the Proteles, which presents the most anomalously simple dentition
in the adult state, a much greater conformity with the common
(1) This Law is defined and exemplified in my * Lectures on the Invertebrate Animals,’ p. 368, 8vo. 1843.
type in the teeth of the immature period of existence. M. de
Blainville describes the deciduous dentition as including, besides
the usual number of incisors and canines, the same number and
kind of molars, as in the other Canidce I i. e. a premolar with two
fangs, a sectorial and a complex molar each with three fangs,(1) (in
the upper jaw?). These are succeeded, in both jaws by four small,
simple, widely separated molars (PI. 125. fig. 6): the first has a sub-compressed
conical crown supported by a single fang; the second has
a larger crown of similar shape supported by two fangs ; the third
molar has a shorter and broader crown supported by two fangs;
the fourth molar is the smallest, with a subtriquetral crown above,
and a simple compressed one below, where it is supported by a
single fang. In this instance of arrested development of the
molar series we may discern the retention of the more strictly
carnivorous (feline) type, though feebly manifested.
In the Megalotis or Long-eared Fox (Otocyon, Licht.) the deviation
from the typical dentition of the Canidce is effected by excess of development
; two additional true molars being present on each side of
the upper, and one on each side of the lower jaw, in the permanent
series of teeth; and an approach is made by the modified form of
the sectorial molar and of some of the other teeth to the dentition
of the genus Viverra.
The upper incisors are small, simple, the outer one separate
from the rest and pointed; the under incisors are sub-bilobed,
relatively smaller than in the Fox. The canines are shorter and
less compressed than in the Fox. The first three premolars (PI. 125,
fig. 5, p. 1, 2, 3) have shorter and more conical crowns, especially the
last; and the sectorial' tooth (p 4) is more advanced ; the trenchant
portion of the sectorial is shorter and the inner tubercle larger than
in the typical Canidce, in which it retains more of the form of its
deciduous predecessor. The first, second, and third true molars have
the internal basal ridge more developed than in the tuberculate
molars of the Fox: the last molar is disproportionately small, like
that of the under jaw in the typical Canidce. The lower premolars,
like the upper ones, are more conical and shorter in proportion to
(1) Osteographie de Canis, p. 56.
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