ridge continued obliquely upwards from above the upper edge o f the petrous bone,
that the cerebellum has been situated wholly behind the cerebrum ; we learn also
from the same structure o f the enduring parts that these perishable masses were not
divided, as in the Manis, by a bony septum, but by a membraneous tentorium, as in
the G lossothere and Armadillos : in the Orycteropus, as has been before remarked,
there is a strong, sharp, bony ridge extending into each side o f the tentorium.
The vertical diameter o f the cerebellum and medulla oblongata equals that o f
the cerebrum, and is two inches three lines : the transverse diameter o f the cerebellum
was about three inches nine line s; its antero-posterior ex tent about one inch
and a half. The sculpturing o f the internal surface o f the cranial cavity bespeaks
the high vascularity o f the soft parts which it contained, and there are evident
indications that the upper and lateral surfaces o f the brain had been disposed in a
few simple parallel longitudinal convolutions. The two anterior condyloid fora-
mina(?n) have the same relative position as the sing le corresponding foramen in
the Glossothere, Orycterope, and Armadillos, and the inner surface o f the skull
slopes outwards from these foramina to the inner margin o f the occipital condyle.
O f the bones o f the face there remain only portions o f the malar, lachrymal,
palatine, and maxillaries. The chie f peculiarities o f the malar bone have been
already noticed ; the breadth o f the base o f the descending masseteric processes is
two inches two lin e s; its termination is broken off: the length o f the ascending
post-orbital process o f the malar cannot be determined from the same cause, but
it is fortunate that sufficient o f this part o f the cranium should have been
preserved to give this evidence o f the affinities o f the Scelidothere to the
Megathere. The malar bone is continued anteriorly, in a regular curve forwards
and upwards, to the lachrymal bone, and completes, with it, the anterior boundary
o f the orbit : the size o f the orbit is relatively smaller than in the Orycterope, and
still le ss than in the Ant-eaters : here, however, we have merely an exemplification
o f the general law which regulates the relative size o f the eye to the body in the
mammalia. Th e malar bone does not extend so far forwards in front o f the orbit
as in either the Orycterope or Armadillo ; in the inclination, however, with which
the sides o f the face converge forwards from the orbits, the Scelidothere holds an
intermediate place between the Armadillos and Orycterope.
The lachrymal bone does not extend so far upon the face in the Scelidothere
as in the Orycterope; in which respect the Scelidothere resembles more the Megathere.
The foramen for the ex it o f the infra-orbital nerve lias the same situation near
the orbit as in the Megathere ; its absolute distance from the anterior border o f the
orbit is only h a lf that in the Orycterope. Th e foramen is single in the Scelidothere,
as in the Orycterope ; in the Megathere there are two or three antorbital foramina.
The vertical diameter o f this foramen is eight lines, the transverse diameter four
line s. So much o f the outer surface o f the superior maxillary bones as has been preserved,
is smooth and vertical. Each superior maxillary bone contains the sockets
o f five teeth, occupying an antero-posterior ex tent o f three inches seven lines, (PI.
X X I I and X X I I I . fig. 3). T h e posterior alveolus is situated ju st behind the transverse
line, extending across the anterior boundary o f the orbits ; the remaining
sockets o f the molar series extend forwards three inches in front o f the orbits. In
the Megatherium, the roots o f the five superior molars are all situated behind the
anterior boundary o f the o rb it: in the Orycteropus, on the contrary, the grinders
are all placed iu advance o f the orbit; so that the Scelidothere resembles that spe cie s
more than the Megathere in the relative location o f the teeth. The palatal interspac
e between the roots o f the last molar tooth o f each series is eleven lin e s; the
palate gradually though slightly widens, as it advances forwards: the posterior
margin o f the palate is terminated by an acute-angled notch. In the breadth
o f the bony palate the Scelidothere is intermediate betw’een the Megathere and
Orycterope.
The anterior o f the upper molars is represented at fig. 3, 4, and 5, PI. X X L , and
at I, fig. 3, PI. X X I I I .; it corresponds closely in form and size with the opposite
molar below ; the base of the triangle given by its transverse section is turned
inwards and obliquely forwards.
The second molar o f the upper jaw, also presents in transverse section a
triangular form, with the angles rounded o f f ; but the inner side o f the tooth is
traversed by a longitudinal groove. The largest diameter o f the transverse
section, which is placed obliquely as regards the ax is o f the skull, measures ten
lines and a h a lf ; the opposite diameter o f the tooth is six lines.
The third and fourth molars present the same form and size, and relative
position as the second.
The fifth molar is the smallest o f the series ; its transverse section gives au
inequilateral triangle, with the corners rounded off; the broadest side is turned
outwards, and is sligh tly concave ; the antero-posterior diameter o f this tooth
is seven lin e s ; the transverse four lines. The length o f the teeth in the upper
jaw is about two inches and a half.
It is almost superfluous to observe that the teeth o f the Scelidothere, as
iu other B ru ta , are without fangs, and have their inserted base excavated b}-
large conical cavities, for the lodgment o f a persistent pulp. The tooth is composed
o f a small central body o f coarse ivory or ‘ dentine,' traversed by medullary
canals, which at the periphery o f the coarse dentine anastomose by loops,
from the convexity o f whicli the calcigerous tubes are given off which form
the fine dentine: the layer o f this substance, whicli immediately surrounds the
coarse dentine, is about one line and a h a lf in thickness, and the whole is
invested with a very thin coating o f cement. The teeth o f tJie Scelidothere thus
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