TEETH
911
both jaws ; the second premolar displaces
the first normally developed deciduous molar;
the third upper premolar displaces and suc¬
ceeds the deciduous sectorial, which has a
sharper and more compressed blade, and a
relatively smaller internal tubercle, than the
permanent sectorial. This tooth displaces
the last deciduous molar, which is a tubercular
tooth, resembling in form the first of the two
upper permanent tuberculars ; these coming
into place without pushing out any prede¬
cessors, enter into the category of true molar
teeth. In the lower jaw the third premolar
displaces the deciduous sectorial, which has
three trenchant lobes and a relatively smaller
posterior talon than the permanent sectorial.
The fourth premolar displaces the third
or tubercular milk-molar. The permanent
sectorial and tubercular molars displace
no predecessors, and are therefore m. 1 and
m. 2.
The first premolar, p. 1, is not developed
at any period in the Mangues (Crossarchus),
the Suricates (Ryzœna), or the Mangusta
•paludinosa ; these Viverrines, therefore, retain
throughout life more of the immature cha¬
racters of the family, and in the same degree
approach in the numerical characters of their
dentition to the more typical Carnivora.
The alternate interlocking of the crowns of
the teeth of the upper and lower jaws, which is
their general relative position in the Carnivora,
is well marked in regard to the premolars
of the Viverridce (fig. 580, IV.) : as the lower
canine is in front of the upper, so the first
lower premolar rises into the space between
the upper canine and first upper premolar ;
the fourth lower premolar in like manner fills
the space between the third upper premolar
(p. 3) and the sectorial tooth (p. 4), playing
upon the anterior lobe of the blade of that
tooth which indicates by its position, as by
its mode of succession, that it is the fourth
premolar of the upper jaw. The first true
molar below, modified as usual in the Car¬
nivora to form the lower sectorial, sends the
three tubercles of its anterior part to fill the
space between the sectorial (p. 4) and the
first true molar (m. 1) above. In the Mu-
sangs the lower sectorial is in more direct
opposition to its true homotype, the first
tubercular molar in the upper jaw ; and these
Indian Viverridce (Paradoxuri) are the least
carnivorous of their family, their chief food
consisting of the fruit of palm -trees, whence
they have been called “ Palm-cats.”
Hyæna.— The dentition of this genus pre¬
sents a nearer approach to the strictly car¬
nivorous type by the reduction of the tuber¬
cular molars to a single minute tooth on each
side of the upper jaw, the inferior molars
being all conical or sectorial teeth : the molar
teeth in both jaws are larger and stronger,
and the canines smaller in proportion than in
the Feline species, from the formula of which
the dentition of the hyæna differs numerically
only in the retention of an additional pre¬
molar tooth, p. 1 above and p. 2 below,
on each side of both jaws. The dental
3_3
formula of the genus Hyæna is: — in. ——-,
1—1 4—4 1—1 3—3
c‘ JUT5 Pm' 3H3’ m‘ 1ZI7: =: 34. The
crojvns of the incisors form almost a straight
tranverse line in both jaws, the exterior
ones, above, being much larger than the
four middle ones, and extending their long
and thick inserted base further back : the
crown of the upper and outer incisor (i. 3.)
is strong, conical, recurved, like that of a
small canine, with an anterior and posterior
edge, and a slight ridge along the inner side
of the base. The four intermediate small
incisors have their crown divided by a trans¬
verse cleft into a strong anterior, conical lobe,
and a posterior ridge, which is notched ver¬
tically; giving the crown the figure of a
trefoil. The lower incisors gradually increase
in size from the first to the third ; this and
the second have the crown indented ex¬
ternally ; but they have not the posterior
notched ridge like the small upper incisors ;
the apex of their conical crown fits into the
interspace of the three lobes of the incisor
above. The canines have a smooth convex
exterior surface, divided by an anterior and
posterior edge from a less convex inner side :
this surface is almost flat and of less relative
extent in the inferior canines. The first
premolar above (p. 1) is very small, with a
low, thick, conical crown : the second presents
a sudden increase of size, and an addition of
a posterior and internal basal ridge to the
strong cone. The third premolar exhibits
the same form on a still larger scale, and is
remarkable for its great strength. The pos¬
terior part of the cone of each of these
premolars is traversed by a longitudinal ridge.
The fourth premolar is the carnassial tooth,
and has its long blade divided by two notches
into three lobes, the first a small thick cone,
the second a long and compressed cone, the
third a horizontal sinuous trenchant plate : a
strong triedral tubercle is developed from the
inner side of the base of the anterior part of
the crown. The single true molar of the
upper jaw (m. l) is a tubercular tooth of
small size : transversely oblong in the Hyæna
vulgaris and H.fusca; smaller and sub-cir¬
cular in the Hyæna crocuta ; still smaller and
implanted by a single fang in the Hyæna
spelæa : in all the existing species of Hyæna it
has two fangs. The first premolar of the lower
jaw (p. 2) fits into the interspace between the
first and second premolars above, and answers,
therefore, to the second lower premolar in
the Viverridæ : it is accordingly much larger
than the first (p. 1) above ; it has a ridge in
the fore-part of its cone, and a broad basal
talon behind. The second (p. 3) is the
largest of the lower premolars, has an anterior
and a posterior basal ridge, with a vertical
ridge ascending upon the fore as well as the
back part of the strong rounded cone : the
third premolar (p. 4.) is proportionably less
in the Hyæna crocuta than in the H. vulgaris:
its posterior ridge is developed into a sma-i
cone; the last tooth (m. 1) is the sectorial,
