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408 DENTAL ANAT031Y.

The third division, inferior maxinary, passes out of the skull through
the foramen ovale, just outside of which it is joined by tlie motor root.
It then divides into two branches, a small anterior one distributed to
the muscles of mastication, and a large posterior branch, which supplies
the ear, side of the head, lower lips, gums, teeth, salivary glands, and
inside of the mouth. The posterior branch divides into the auricido-tem-
jjoral, which passes backward to the temporal region ; the inferior dental,
which supplies the teeth of the lower jaw ; and the c/nstatory, or the nerve
of taste, which goes to the mucous membrane of the tongue.
The lips, tongue, and salivary glands should also be mentioned in
connection with the accessory organs, since they serve an important
purpose in preventing small particles of the food from escaping during
mastication, as well as supply the requisite moistening fluid Avherebv
comminution is more readily accomplished and the food rendered more
digestible.

Teeth of the Edentata, or Bruta.

Although this group is by no means the most primitive of the INIam-
nialia, as will be seen by reference to the table of classification, yet the cha-
racters which we have assigned to the ideal primitive mammalian dentition
are most nearly approached in certain members of this order. Whether
the comparatively simj)le form and absence of enamel in the adult tooth,
which is characteristic of all the animals of this order, pertain to a prim-
itive state, or whether this condition has been reached by a process of
retrogression or degradation, as many believe, we are not at present pre-
pared to say, in the absence of any knowledge of their paleeontological
history beyond the latest Tertiary epoch. There is one character, how-
ever, in which one at least is more decidedly primitive than any other
known Eutherian mammal, and that is the succession of all the teeth bid
one (the last) by a second set. I refer to the nine-banded armadillo
(Tcdusia peba). It is not certainly known whether this condition exists
in any other of the edentates or not, with the exception of the sloths,
which are truly monophyodont.
The term Edentata is inappropriate, inasmuch as one would be led to
suppose from the name that they have no teeth. The original term,
Bruta, Avas applied to this order by IJnnpeus, which he defined by the
absence of incisor teeth. It was afterward changed to Edenteda by
Cuvier—a name which has been extensively adopted by subsequent
authors. It was formerly supposed that no incisor teeth are ever pres-
ent in this group, but the discovery of new forms proved this to be
erroneous. The median incisors, however, are wantine; in all cases so
far known. The definition of the order now most commonly given
is " absence of enamel on the teeth." This peculiarity appears at first
sight striking and quite sufficient to separate them froni all other mono-
delphous mammals, but C. 8. Tomes has shown ^ that the tooth-germs
of the nine-banded armadillo have distinct enamel organs, which are
subsequently aborted as the tooth comes to maturitv. This discovery is
important, since it indicates pretty clearly that the loss of enamel is a
^ Philos. Trans., 1876.