So that, for the skull, no
less than for the skeleton in general, the proposition holds good, that
the differences between Man and the Gorilla are of smaller value than
those between the Gorilla and some other Apes.
In connection with the skull, I may speak of the teeth--organs which
have a peculiar classificatory value, and whose resemblances and
differences of number, form, and succession, taken as a whole, are
usually regarded as more trustworthy indicators of affinity than any
others.
FIG. 17.--Lateral views, of the same length, of the upper jaws of
various Primates. 'i', incisors; 'c', canines' 'pm', premolars; 'm',
molars. A line is drawn through the first molar of Man, 'Gorilla',
'Cynocephalus', and 'Cebus', and the grinding surface of the second
molar is shown in each, its anterior and internal angle being just
above the 'm' of 'm2'.
Man is provided with two sets of teeth--milk teeth and permanent teeth.
The former consist of four incisors, or cutting teeth; two canines, or
eyeteeth; and four molars, or grinders, in each jaw--making twenty in
all. The latter (Fig. 17) comprise four incisors, two canines, four
small grinders, called premolars or false molars, and six large
grinders, or true molars, in each jaw--making thirty-two in all.
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