Bauhaus-Universität Weimar

Titel:
The Cyclopaedia of Anatomy and Physiology, vol. 4: Pla [corr.: Ple] - Wri
Person:
Todd, Robert Bentley
PURL:
https://digitalesammlungen.uni-weimar.de/viewer/image/lit29465/920/
TEETH. 
910 
chairodus, fig. 580, VI.*), the series is still fur¬ 
ther reduced by the loss ofp. 2 in the upper jaw. 
That the student may test for himself the 
demonstration which the developmental cha¬ 
racters above defined, yield of the true nature 
and homologies of the feline dentition,— the 
most modified of all in the terrestrial Carnivora, 
he is recommended to compare with nature 
the following details of the appearance and 
formation of the teeth in the common cat. 
In this species the deciduous incisors d.i. begin 
to appear between two and three weeks old ; 
the canines d. c. next, and then the molars d. m. 
follow, the whole being in place before the 
sixth week. After the seventh month they 
begin to fall in the same order; but the lower 
sectorial molar m. 1, and its tubercular homo¬ 
type above (m. 1) appear before d. 2, d. 3, and d. 4 
fall. The longitudinal grooves are very faintly 
marked in the deciduous canines. The first 
deciduous molar (d. 2), in the upper jaw is 
a very small and simple one-fanged tooth ; it 
is succeeded by the corresponding tooth of the 
permanent series, which answers to the second 
premolar ( p. 2) of the hyaena and dog. The 
second deciduous molar (d. 3) is the sectorial 
tooth ; its blade is trilobate, but both the anterior 
and posterior smaller lobes are notched, and 
the internal tubercle, which is relatively larger 
than in the permanent sectorial, is continued 
from the base of the middle lobe, as in the 
deciduous sectorial of the dog and hyæna ; 
it thus typifies the form of the upper sectorial, 
which is retained in the permanent dentition 
of several Viverrine and Musteline species. 
The third or internal fang of the deciduous 
sectorial is continued from the inner tubercle, 
and is opposite the interspace of the two 
outer fangs. The Musteline type is further 
adhered to by the young Feline in the large 
proportional size of its deciduous tubercular 
tooth, d. 4. In the lower jaw, the first milk- 
molar (d. 3) is succeeded by a tooth (/>. 3) which 
answers to the third lower premolar in the 
dog and civet. The deciduous sectorial (d. 4), 
which is succeeded by the premolar (p. 4), an¬ 
swering to the fourth in the dog, has a smaller 
proportional anterior lobe, and a larger pos¬ 
terior talon, which is usually notched ; thereby 
approaching the form of the permanent lower 
sectorial tooth in the Mustelulce. 
In the article Carnivora (vol. i. p. 478.), 
the remarks on the teeth are limited chiefly to 
their physiological adaptations. A description 
of some of their more remarkable structures 
will here be given, according to the idea of the 
nature of the teeth above developed. The 
dental formula of the dog, jackal, wolf, and 
fox, is illustrated in fig. 580, III. Canis. 
* Machairodus, from a sabre ; and o&ol;, 
a tooth. This generic name was imposed by 
Dr. Kaup on the extinct animal which was armed 
with canine teeth, like that figured in fig. 580, YI. 
Such teeth, long, compressed, falciform, sharp- 
pointed, and with anterior and posterior finely- 
serrated edges, were first discovered in tertiary 
strata in Italy and Germany, and were referred by 
Cuvier to a species of bear, under the name of Ur sus 
cultridens. Fossil canines of this genus have been 
found in Kent’s Hole cave, Torquay. 
In the Megalotis, or Long-eared Fox (Oto- 
cyon, Licht.), the deviation from the typical 
dentition of the Canidœ 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 Viverridœ. This family of 
Carnivora, which comprehends the Civets, 
Genets, Ichneumons, Musangs, Sarikates, and 
Mangues, is characterised, with few exceptions, 
3_3 I_i 
by the following formula : — i. ^^ ; c. -,— ; 
4_4 g_2 
p. ^ y ; m. g_Q : = 40. It differs from that 
of the genus Canis by the absence of a tubercu¬ 
lar tooth (m. 3) on each side of the lower jaw ; 
but, in thus making a nearer step to the 
typical carnivorous dentition, the Viverridœ, 
on the other hand, recede from it by the less 
trenchant and more tubercular character of 
the sectorial teeth, as is shown in the figures 
of the teeth of the Viverra indica, in my “ Odon¬ 
tography,” pi. 126. figs. 1, 2, and 3. 
The canines are more feeble, and their 
crowns are almost smooth ; the premolars, 
however, assume a formidable size and shape 
in some aquatic species, as those of the sub¬ 
genus Cynogale, in which their crowns are 
large, compressed, triangular, sharp-pointed, 
with trenchant and serrated edges, like the 
teeth of certain sharks, (whence the name 
Squalodon, proposed for one of the species), 
and well adapted to the exigencies of quad¬ 
rupeds subsisting principally on fish : the op¬ 
posite or obtuse, thick form of the premolars 
is manifested by some of the Musangs, as 
Paradoxurus auratus. The upper sectorial 
tooth, p. 4, is characterised by having its inner 
tubercle larger, the middle conical division of 
the blade thicker, and the posterior one smaller 
than in the genus Canis. This tooth advances 
to beneath the ant-orbital foramen in the Mu¬ 
sangs (Paradoxurus) : it is situated farther 
back in the Civets and Genets, in which the 
blade of the sectorial is sharper. This shmvs 
that relative position to the zygomatic or molar 
process of the maxillary is not a good cha¬ 
racter. 
In the lower jaw the sectorial tooth (m. 1) 
manifests its true molar character by the pre¬ 
sence of an additional pointed lobe on the 
inner side of the two lobes forming the blade 
at the fore-part of the crown : the posterior, 
low, and large lobe of the tooth being also 
tri-tuberculate, as in the dog. The last 
molar (m. 2) has an oval crown with four small 
tubercles, resembling the penultimate lower 
molar in the dog, with which it corresponds. 
The deciduous dentition consists, in the 
3_3 
Viverrine family, of : incisors -—— ; canines 
O-ô 
]_j 3_3 
y—; molars y—y : = 28. If the first per¬ 
manent premolar has any predecessor, it 
must be rudimental and disappear early in
        

Nutzerhinweis

Sehr geehrte Benutzer,

aufgrund der aktuellen Entwicklungen in der Webtechnologie, die im Goobi viewer verwendet wird, unterstützt die Software den von Ihnen verwendeten Browser nicht mehr.

Bitte benutzen Sie einen der folgenden Browser, um diese Seite korrekt darstellen zu können.

Vielen Dank für Ihr Verständnis.