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ers ofthe upper jaw, which have in general three roots, the pulp
is divided into as many processes, and the osseous bars shoot-
ing through them, from as many different points in the mar-
gin of the shell, and uniting in the middle, divide the cavity
into three openings, two of which are placed externally,
and one internally. Sometimes an osseous point is deposit-
ed in the centre of these processes, and fibres shooting across
from the margin of the shell join it, which answers the same
purpose.* From these openings, the processes of the pulp
commonly become more and more divergent and ossification
extending on them forms a conical or flatted tube on each,
as in teeth which have but single roots. Sometimes the
pulp is divided at the neck only into two processes ; ossifica-
tion goes on for some time as usual, but one tooth or both
of these become divided again, and so three or four roots
are formed. I have met a few of the permanent grinders,
in which the pulp did not divide into processes, so that only
one root was formed. The pulp continues to advance faster
than the ossification, until each process has acquired its
proper length and shape ; then the pulp except where the
vessels and nerves enter, becomes entirely surrounded with
bone.
Mr. Hunter mcntions,f " by the observations which I have
made in unravelling the texture of the teeth when softened
by an acid, and from observing the disposition of the red
parts in the tooth of growing animals, interruptedly fed with
madder, I find that the bony part of a tooth is formed of
lamellae, placed one within another. The outer lamella is
the first formed, and is the shortest : the more internal lam-
ellae lengthen gradually towards the fang, by which means in

* Albin. Acad. Annot. Lib
11. P. 17.
t Nat. Hist, page 92.