is figure,
which is from a plate published by Professor Selenka.

It must be noted that the number of tubercles on the true molars may
be in exceptional cases one more or one less than that given in this
drawing which gives the most usual number. The word "molar" is often
used to include the five cheek-teeth on each side of each jaw, but
more strictly the anterior bicuspid teeth are called "pre-molars," and
the three larger teeth behind them, which have no predecessors or
representatives in the first or milk dentition, are called true molars
or simply "molars"--a rule we have followed here.

In both upper and lower jaw we see the four incisors in the middle
(Inc. 1, Inc. 2); on each side of them is the conical crown of a
canine--a tooth which is greatly enlarged in the ape (see Pl. VII),
but is no larger proportionately than it is here even in the most
ancient known human jaw, that from the Pleistocene of Heidelberg (see
"Science from an Easy Chair," Methuen, 1910, p. 405). The two small
bicuspid "pre-molars" and the three large molars follow these on each
side in each jaw. The crown of the most anterior (or "first") molar of
the upper jaw has four cusps, tubercles, or cones on it. It is
"quadri-tuberculate." The second and third molars of the upper jaw
have three such prominent tubercles (excluding a row of small
tubercles on the hinder margin of the second); they are, in fact,
tri-tuberculate; whilst the two hindermost molars of the lower jaw
have four tubercles and are called quadri-tuberculate. The first molar
(M1) of the lower jaw has in this specimen five tubercles. In 60 per
cent. of European lower jaws this is the case. But in 40 per cent.
this tooth is quadri-tuberculate. In Polynesians, Chinese, Melanesians
and negroes five tubercles are found on this tooth in 90 per cent. of
the jaws examined. The apes are characterised by five tubercles on
this tooth, and they are found also on the first lower molars of
prehistoric men. Four tubercles only on this tooth is a departure from
the ape's condition and is found more frequently in Europeans.

It is obvious that these big molar teeth, as well as the two smaller
ones in front of them on each side of each jaw, are adapted for
breaking up rather soft, pulpy food, and not for cutting lumps of bone
or raw flesh, as are the molars of the clouded tiger (identical with
those of all species of the genus _Felis_), shown in Figs. 21 and 22,
pp. 103, 104, nor for rubbing gra