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436 DENTAL ANATO^IY.

connection between the internal cu:^p and the postero-external tubercle,
which generally exists in the tritubercular tooth. The postero-internal
cusp, which lies inside and behind this ridge, is the last one which has
been added to complete the quadritubercular tooth in the upper jaw. In
the squirrel monkeys of this family the lower incisors have a tendency
to be proclivous, as in Hapale of the marmosets, thus retaining the
lemurine character of these parts. Xo fossil remains of this family are
known except from very late geological time, and these do not difller
materially from those now living.
The teeth of the Catarrhines {Semnopithecidce) show a reduction in
the number of premolars, whereby the tbrnnda I. C. \, Pm. |-, M.
f, f
= 32, the same as that of man, is reached. The incisors are of the
same shape as in man, the central pair being considerably larger than
the outer pair. The canines are always strong and powerful teeth, and
their apices are always elevated above the other teeth. They reach their
maximum of development in the baboons, more especially in the dog-
headed baboon, Ci/nocephalus, in which they are deeply grooved ante-
riorly. In this group the first premolar below is implanted by a double
fang, with its apex directed upward and backward. The anterior root
is naked for some distance, and presents in front a blunt edge Avliich
bites against the posterior edge of the powerful superior canine, giving
to this part of the jaw a peculiar and characteristic appearance. The
second lower premolar of Cynocephalus is quadritubercular, with all the
cusps well developed, but in the macaques the posterior tubercles are
not well defined. Both the ujiper and lower true molars increase in size
from the first to tlie last, the last lower one being distinctly five-lobed.
In the semnopithiques the incisors are more nearly equal in size ; the
canines are smaller and less deeply grooved than in the baboons ; the first
and second molars are subequal, while the last lower molar is propor-
tionally narrower, but still retains the fifth lobe. The typical cerco-
pithiques have the last lower molar quadritubercular and all the molars
subequal. Fossil remains of this family are known from the Miocene
and Pliocene deposits of Europe and Asia, but no characters of unusual
importance occur in their dentition.
The next family of this order includes the anthropoid or tailless apes,
which are also confined to the tropics of the Old World. They consti-
tute the family Simiidcp, and are distinguished from the preceding fam-
ily, CcrcopitheclcJcc, principally by the absence of the tail ; from the suc-
ceeding family, Homimdce, by the circumstance that the hallux is oppos-
able, whereas in the latter it is in a line with the other digits and is not
opposable. Other characters of considerable anatomical importance are
also found which distinguish them from man.
The teeth of this family are the same in number as those of man,
but considerable differences are found in the relative size of the canines
and the last molar when compared M'ith that which obtains in the
human subject. Although they are organized substantially upon the
same plan, the teeth are larger and stronger than in man. The orang
(Simla i^afjfnts) is j)robably the most human-like in its dentition, although
in other respects the gorilla and chimpanzee most resemble man. The
molar teeth in this animal are remarkable for the straight line in which