183 
PANTODONTA. 
imcertain. The palate is rather narrow, and of moderate length; it is 
notched posteriorly by the posterior nares only a little anterior to the line 
of the posterior borders of the molar teeth. The palatine bone has a small 
an tero-posterior extent. Its processus py ramidalis, with the pterygoid processes 
of the sphenoid, forms an elongate undivided lamina lateralis of the posterior 
nares, which presents an angle downward, from which the posterior border 
rises to the axis of the skull near the transverse line of the glenoid cavities. 
The foramen ovale perforates the base of a short descending process. The 
foramen lacerum is not large, and a small truncate styloid process is con¬ 
cealed on the side of the small petrous bone. The basioccipital is nearly flat 
on the median line below. The postglenoid processes are well developed. 
The paramastoid and mastoid processes are fused into a single descending 
mass of moderate length. The meatus auditorius externus is not inclosed 
below. 
The form of the mandible is peculiar. The angle is not inflected, and 
is elevated above the usual position in consequence of an upward curvature 
of the inferior border of the ramus, commencing below the last molar tooth. 
The cond 3 de is large, and has considerable transverse extent, and its articu¬ 
lar surface is presented as much upward as backward. The coronoid pro¬ 
cess is elevated and stout; the rami are slender for the general robustness 
of the skeleton, and the symphj^sis is rather long and co-ossified. The form 
of tlie ramus is not a little like that of many Insectivora. 
The brain-cavity is remarkable for its very small size as compared 
with that of the skull. In the antero-posterior direction, the cerebral 
hemispheres did not extend anterior to the glenoid surfaces, while in the 
American Tapir they reach as far as the posterior border of the last superior 
molar tooth. The olfactory cavities are much longer in the Coryphodon, 
but do not extend to the line of the last superior molar tooth. In vertical 
diameter, the brain-cavity is less than half that of the portion of the skull 
in which it is situated, a large space above it being occupied by pneumatic 
chambers, which perhaps represent the diploe of thinner-walled skulls. 
The external walls of these spaces are only moderately thick. There are 
two principal lateral cavities, which are separated by a thin antero-posterior 
septum. They widen posteiiorl}', and each is divided by partial septa, 
