ELEPHAS PRIMIGENIUS, PAPAL 
those teeth, in the important question of the species or 
varieties of Mammoth that formerly inhabited England. 
The crown of the molar of the Mammoth, like that of the 
existing species of Elephant, consists of, or is divided into, 
a number of transverse perpendicular plates, composed of 
two distinct substances, and cemented together by a third 
substance. The body of each plate consists of the basal 
constituent of a tooth called “dentine,” of which ivory 
is a modification; it is marked d, in the figures of the 
teeth in this section. The dentine is coated by a layer 
of harder substance called ‘“‘enamel” (¢), and the inter- 
spaces of the plates so formed are filled by a less dense 
substance called ‘‘ cement” (¢), because it fastens together 
the several divisions of the crown, and more strikingly 
fulfils the office of cement when those divisions are incom- 
pletely formed and not united by mutual confluence. 
As the growth of each plate begins at the summit, they 
remaim detached and like so many separate teeth or denti- 
cules, until their base is completed, when it becomes ex- 
panded and blended with the bases of contiguous plates to 
form the common dentinal body of the crown of the com- 
plex tooth, from which the roots are next developed. 
But the composition and growth of the plates are analogous 
to, and almost as complex as, that of the entire tooth ; each 
plate consists at first of a series of separate slender 
conical columns or digital processes, arranged transversely 
across the tooth. The formation of these columns begins 
at their summit, and descends, their bases gradually ex- 
panding until they are blended together to form a continu- 
ous transverse plate; just as the plates are subsequently 
blended together to form the continuous longitudinal crown 
of the whole grinder, The digital processes and the 
digitated plates of an incompletely developed tooth are held 
Qua 
