upper jaw, j nat. size, of a Colt of two
years. Fig. 6. The dentition of a Colt of
three years, from the inner side of the
upper jaw, j nat. size. Rousseau. Fig.
7. The incisors and canine of the left side
of the lower jaw of a Colt of four years,
nat. size. The third permanent incisor,
i 3, has not yet displaced its deciduous
predecessor, d, i 3. Rousseau. Fig.
8. The incisors of the right side of the
upper jaw of a Horse of five years, shewing
the mark a, long and deep in all, and
irregular on the inside in the outer incisor,
i 3. Fig. 9. The upper incisors and canine
of the right side of a Horse of six
years, shewing the mark faint in the first
and second incisors; hut the inflected
margins and point of the canines, c, are
still sharp. Fig. 10. The upper incisors
and canine of the right side of an aged
Horse, about sixteen years. The cavity
of the mark is obliterated; the dark coloured
osteo-dentine, and some remains
of cement in the outer incisor, indicate
their place; the margins and point of the
canine are rounded off. Fig. 11. Longitudinal
section of an incisor showing the
depth of the vertical fold of enamel a, and
the cement at its bottom a '; e, is the outer
enamel and c, the outer cement. Rousseau.
PLATE 137.
A section of part of the crown of a molar of
a Horse, showing a dentine; b, enamel;
c, cement, in which are many vascular
canals, v v. Magnified 150 linear diameters.
Original.
PLATE 138.
Fig. 1. Reduced view of the skull of the
extinct hornless Rhinoceros, (Acerothe-
rium incisivum), Kaup, Fig. 2. Reduced
view of the skull of the two horned Rhinoceros
(Rhinoceros bicomis). Cuvier.
Fig. 3. Grinding surface of molar series,
right side upper jaw, ^ nat. size, of the one-
homed Rhinoceros (Rh. indicus), Cuvier.
Fig. 4. Grinding surface of first true molar
of the Java Rhinoceros (Rh. sondaicus).
Fig. 5. Ditto of the Rhinoceros bicomis.
Fig. 6. Ditto of the Rhinoceros tichorhinus.
Fig. 7. Ditto of the Rh. leptorhinus. Fig.
8. Germ of a molar of Rh. tichorhinus.
All the above figures of upper molars are
reduced § in size : o, outer side; o1 longitudinal
ridge; i i, inner lobes; b, valley
dividing the inner lobes ; e, its termination
which becomes wholly, or partially,
or not at all insulated, according to the
species; c , valley entering from outer
side (it is marked e, in fig. 4). f . Pro-
montary projecting into or crossing valley
b. Fig. 9. Grinding surface of two molars
of the lower jaw, ^ nat. size, of Rhin.
indicus. Fig. 10. Four premolars, leftside
lower jaw, with symphysis in outline, of
the Rhin. tichorhinus, ^ nat. size. Fig.
11. Four premolars left side, lower jaw,
and symphysis of the Rhin. leptorhinus;
£ nat. size. Fig. 12 (printed 1). Outline
of the right intermaxillary hone of
the two-horned Rhinoceros of Sumatra.
(Rh. Sumatranus), J nat. size; i 1, first
incisor; i 2, second incisor. Fig. 13.
Portion of left superior maxillary bone of
a young Rhinoceros Indicus showing c rudiment
of a canine, and p 1 the hidden
crown, exposed from without, of the first
premolar. Fig. 14. Symphysis and part
of lower jaw of a very young Rhinoceros
bicomis, j nat. size, showing the germs
of four incisors (i 1 and i\2 on each side);
d 1, first deciduous molar; d 2, second
deciduous molar. Fig. 15. Symphysis
of lower jaw of a half-grown Rhinoceros
Wm, sumatranus; i 1, small mid-incisor; i 2,
I f end of the germ of the large second or
outer incisor; d 2, its deciduous prede-
:|I cessor about to fall; it has been shed on
if the opposite side; d 1, two small orifices
i : above the mid-incisors, qu. remains of
);| sockets of deciduous teeth ? Original.
PLATE 139.
A section of the crown of the molar of a
(M Rhinoceros, magnified 230 linear diameter:
i| t, obliquely divided ends of the dentinal
f!> tubes ; d', peripheral contour of dentinal
B cells ; d", terminal and intertubular cellules
; l, contour lines; e, enamel. Ori-
ginal.
PLATE 140.
Fig. 1. Right upper and lower jaws
» with the teeth and their nerves exposed
» f rom the inside, § nat. size, Hog, (Sus
H scro/o). Fig. 2. Deciduous and perma-
Ijl'nent teeth of right ramus lower jaw of a
young Hog, J nat. size, exposed from
i ||th e inner side. Rousseau. Fig. 3. Skull
S an d teeth of the Barbiroussa, nat. size.
7 v Original. Fig. 4. Molar series, right
■ sid e , upper jaw, nat. size, of an aged
Wart-hog (Phacocharus Pallasii) : the
first true molar has been worn out and
Wshed, and the last premolar, p 4, brought
into close contiguity with the second true
jfmolar, m 2. Original. Fig. 5. Upper
molar of the Charopotamus Cuvieri, nat.
isize. Fig. 6. Upper molar of the Hyra-
cotherium leporimm, nat. size. Fig. 7.
"Upper molar of the Hippohyus sivalensis,
nat. size. Fig. 8. Upper molar of the
Merycopotamus, nat. size. Original.
PLATE 141.
U r Deciduous and permanent teeth of
the right side, lower jaw, of a young
Phacocharus JEliani. Original. Fig. 2.
The permanent molar series of the adult,
showing the worn-out state of the first
true molar, m 1, nat. size. Original.
Fig. 3. The permanent molar series of
an Indian Wild Boar, showing the worn
state of the first true molar, m 1, and a
supernumerary first premolar, nat. size.
Fig. 4. Skull and teeth of a Hippopotamus,
f nat- size. Original.
PLATE 142.
Fig. 1. Cut surface; fig. 2, outer surface
of a longitudinal section of the
lower canine tusk of a Hippopotamus,
which has been fractured and reunited at
* *. Original. Fig. 3. A fossil premolar,
nat. size, of a Hippopotamus;
one of the three in the portion of jaw in
the Woodwardian Museum, which is the
original of the figure in ‘ Scilla, de Cor-
poribus Marinis, tab. x ii., fig. 1, 1747.
Original.
PLATE 143.
Fig. 1. Fossil lower jaw and teeth, ;J nat.
size, of a not quite full-grown Hippopo-
tamus (Hexaprotodon) from the Sewalik
tertiary formations, showing the three
incisors on each side of the symphysis,
i i, which form its sub-generic character.
Fig. 2. Lower jaw and deciduous teeth,
a nat. size, of a very young Hippopotamus
amphibius : i, incisors; c, canine;
d 1, 2, 3, and 4, deciduous molars; m 1,
first true molar. Fig. 3. Unworn crown
of a true molar of the Hippopotamus amphibius,
) nat. size. Fig. 4. The same
ground down. Original.
PLATE 144.
Figs. 1 to 11 show the entire molar series
c 2