of one side of the lower jaw of the Mastodon
giganteus, J nat. size; I & 2 are
the true deciduous molars; 3 is their
vertical successor or the premolar, (the
original was from the upper jaw). 4, 5,
d 3, the last of the true deciduous series,
which has no vertical successor. Figs. 6
& 7 first true molar (fifth tooth developed
in succession). Figs. 8 & 9. Second
true molar. Figs. 10 & 11. Third
or last true molar. The originals of
these figures are in the British Museum,
and were obtained by Mr. Koch from
newer tertiary deposits in Missouri, North
America. Fig. 12, (marked 11 in the
plate), a fragment of the upper jaw of
the Mastodon angustidens, showing the
deciduous molars, and the premolar, J nat.
size. Fig. 13. Fore part of lower jaw
of a young Mastodon giganteus, showing
d, i, the deciduous incisive tusks ; i 1,
2 & 3, the three deciduous molars, and
p 1, outline of their vertical successor
hypothetically added. Fig. 14. Fractured
fore-part of the lower jaw of adult male
Mastodon giganteus, ^ nat. size, showing
i the permanent lower tusk on the right
side. From the specimen in the British
Museum. Original.
PLATE 145.
Fig. 1. Grinding surface of last lower
molar, in situ, of the Mastodon latidens.
Fig. 2. The same of Mastodon Elephan-
toides : both -j nat size. Clift.* Fig. 3.
Grinding surface of a lower molar of the
Toxodon platensis, nat. size, showing the
partial disposition of the enamel e e ; d, is
the dentine ; c the cement. Original.
PLATE 146.
Fig. 1. Vertical section of the skull of the
Indian Elephant with the molars and in-
* Geological Transactions, Vol. n, 1829.
cisive tusk of one side, the latter, i, showing
its alveolus and pulp-cavity exposed
by a longitudinal section. The dotted
line through the fore-part of the pulp-
cavity shows where a ball might pene-
trate that cavity and lodge at the opposite
side, be there surrounded by osteo-den-
tine, then encased in ivory; and by
progressive growth of the tusk, be afterwards
carried in the direction of the
arrow, into the middle of the solid ex-
serted part of the tusk. The continuation
of the dotted line shows how the
ball, if it had penetrated the base of
the tusk of a young Elephant, might
ultimately be discharged. The semicircular
line described round the central
dot in the nasal cavity, gives
the curve along which the molars advance
in their revolving course from behind
forwards. Part from Cuvier, part
Original. Fig. 2. The penultimate molar
and germ of the last molar exposed
in the lower jaw of the Asiatic Elephant:
a, the bony capsule or alveolus, which
moves forwards with the tooth. Fig. 3.
Right upper jaw of a very young Elephant,
jth n a t. size. Fig. 4. A detached
summit or digital process of a constituent
plate of the molar of an Asiatic Elephant,
nat. size; p, the open pulp-cavity at its
base. Fig. 5. A detached plate of the
same grinder, with a longitudinal section
removed from one half, showing d, the
dentine, e, the enamel, and c, the cement
; nat. size. Fig. 6. Part of the
longitudinal section of an Indian Elephant’s
grinder, showing the interdigita-
tion of the constituent tissues; d, dentine;
e, enamel; c, cement; p, is the common
pulp-cavity; r, the beginning of a root.
Fig. 7. Part of the longitudinal section
of an African Elephant’s grinder. Fig. 8.
Part of a transverse section of the tusk
of an Indian Elephant, showing the de-
(cussating curved lines of the modified
dentine or ‘ivory’; c, the external cement.
Original.
PLATE 147.
Afisection of part of the upper jaw, and
the last molar tooth of a fossil Elephant
(E/ep/tas planifrons. Falconer) from the
'iSIimalayan tertiary deposits ; a a, the
common body of dentine; b, the enamel
covering the coronal lamelliform processes
of dentine; c, the thick mass of cement
filling the intervals of those enamelled
Hprocesses, and accumulated upon them
in the hinder unworn part of the molar:
d d, the roots of the molar. By some
unusual accident to the lower opposing
tooth of the molar of the opposite side,
r, it has not suffered abrasion, but has
] preserved the mammillated summits of all
its plate entire and projecting beyond the
'lifevel of the grinding surface of the molar
in use. Fig. 2. Shows the difference in
the surfaces of the right unworn grinder
r r, and of the worn left grinder 11; a,
dentine; b, enamel; c, cement; L nat.
size. From the specimen presented by
Captain Cautley to the British Museum.
Original.
PLATE 148.
Fig. 1. Side view of first upper molar of
'■Indian Elephant. Fig. 2. Grinding surface
of same; both nat. size. Fig. 3.
Grinding surface of penultimate lower
molar of Indian Elephant. Fig. 4. The
same of an African Elephant. Fig. 5.
Unusually large last lower molar of the
mammoth, (Elephas primigenius). Fig.
6. Penultimate lower molar, of the more
normal form and structure of a mammoth.
Fig. 7. Part of an upper molar of a
mammoth, shewing the transverse ridges
on the margins of the coronal plates. Fig.
8. Much worn molar of a mammoth. Figs.
3 to 8 are ^ nat. size, and in each; d, is
dentine; dt, the same worn down to common
base; e, enamel; c, cement; f , digital
summits of coronal plates; r, root.
Original.
PLATE 149.
A section of the tusk of an Indian Elephant,
magnified 250 linear diameters, showing
the microscopic structure of ivory.
Original.
PLATE 150.
Fig, 1. A section of a part of the exterior
of the root of a molar of the Indian Elephant,
magnified 600 linear diameters;
d, dentine ; d), dilated terminations of the
undulated tubes; cl radiated cell of cement
; e11, cemental tubes. Fig. 2. Longitudinal
section of the end of a root of
the molar of an Indian Elephant, magnified
230 linear diameters ; d, dentine;
c c, cement. Original.
6U1U6 aaoiij isuuiucio 1 y
m 122, are repeated twice, and Numbers 62, 63, 64 and 65, thrice, making a tota
number of 168 plates.
d