by their crowns passing in front of the upper canines; but they
here present more of the laniariform shape and proportions and have,
therefore, been recognised as canines by those Comparative Anatomists,
M. F. Cuvier for instance, who have regarded the analogous
teeth as incisors in the Indris and the higher Lemuridce. The premolars
in the Tarsii are conical, and slightly increase in size as they
approach the true molars : these have the lobes of the crown, especially
the outer ones, produced into sharp points.
The Galagos (Otolicnus) resemble the Malmags in the insectivorous
character of the crowns of the true molar teeth, but have an
additional pair of incisors and smaller canines in the lower jaw. The
dental formula in these, as in the Slow Lemurs (Stenops) is [—
Incisors B ; canines S f ; premolars — ; molars — : I 36.
In the Stenops tardigradusy 1) the first upper incisor is larger than
the second, as in the genus Tarsius, _
The true Lemurs or Makis (Lemur, Geoff.) have the same
number and kind of teeth as the Slow Lemurs. The inferior
canines, PI. 114, (fig. 5, c1), first recognized as such by Geoffroy,
are compressed and procumbent like the incisors, but are a
little larger. In the upper jaw the two incisors are small and
vertical, with short, expanded crowns: the two on the right side
are separated by a wide space from the two on the left. The
canine (c) is long, curved, compressed, sharp-edged and pointed.
The three premolars have the outer part of the crown prolonged
into a compressed pointed lobe, whilst the inner part forms a
tubercle, which is largest in the second and third. In the true
molars the inner division of the crown is so increased as to give
it a quadrate form: the outer division being divided into two
pointed lobes. The first of the true molars is the largest in both
jaws.
The first premolar above is implanted by two connate fangs:
in the second and third they are distinct, and a third inner fang
is developed to support the inner lobe of the crown. Each upper
molar is supported by three short and thick fangs. In the lower
(1) lb. fig. 4.
jaw both premolars and molars are severally implanted by two
fangs; the canines and incisors, in both jaws have each a single
fang, according to the normal mode of implantation of these teeth,
which is henceforth not departed from in the Mammalian Class.
The deciduous series of teeth in the genus Lemur is :—
Incisors — ; canines gSR molars—:= 24.
170. Platyrhines.—All the Quadrumana of America are distinguished
from the Apes and Monkeys of the old world by certain well-
marked external characters : of these, the position of the nostrils at the
sides of the broad nose, whence their collective name, is the most conspicuous
; but they have a more important dental distinction in the
superior number of the premolars, which are §E§, instead of frf;
whereby the American Monkeys manifest their closer affinity to the
Lemurs, and their inferior position in the zoological scale.
The small and delicate platyrhine Monkeys commonly known
in this country by the name of ‘ Marmosets,’ and forming the
genera Hapale and Midas, have but two true molar teeth on each
side of both jaws, their dental formula (PI. 114, fig. 8.) being:—
Incisors o— o ; canines 1——1 ; premolars 3——3 ; molars 2——2 : = 32.
In the Jacchus Marmoset (Hapale Jacchus) the crowns of
the upper incisors are broad and trenchant, the first being the
largest; but the lower incisors continue, as in the Lemurs, to be
long and pointed like the canines, to which they are but little
inferior in size. The upper canines present a character which is
peculiar among Mammalia to the Quadrumana, viz : a longitudinal
groove along the fore-part of the crown. The shape of the crowns
of the premolars is shewn in fig. 8, p : they are each implanted by
a single fang. The first true molar above has three roots, that
below has two; the second molar has a single root in both the
upper and lower jaws. A vacant interspace separates the upper
canine from the incisors ; the teeth of the lower jaw form a continuous
series, as in Man.