320 PALAOTHERIUM. 
The last molar tooth has a more oblong crown than the 
preceding ones, the grinding surface of the tooth being 
more extended in the axis of the jaw; but the posterior 
margin of the tooth is narrower, and the crown approaches 
more to the triangular form. In the collection of S. P. 
Pratt Esq., F.G.S., there is a fine specimen of the germ 
or newly-formed crown of the last molar tooth, from the 
right side of the upper jaw, fig. 112. 
The two concave enamelled surfaces, d, d, separated 
by the three salient ridges, which form the outer wall 
of the crown, are strongly inclined inwards as they extend 
downwards; and each concave surface is produced into 
a point: the enamelled summits of which ‘are entire. 
Descending folds of the formative matrix of the tooth 
have left corresponding sinuous depressions on the surface 
of the crown: one of these (4) extends in a sigmoid form 
from the internal to near the middle of the external 
wall; a second, (#) which begins by a deep fossa at the pos- 
terior border of the tooth crosses the preceding, and extends 
to within a short distance of the anterior border: a ridge is 
continued from each external angle of the crown first down- 
wards, and then inwards to the opposite internal angle; at 
the posterior angle it is continued into a prominent conical 
lobe ; the ridge continued to the anterior angle surrounds 
the base of a larger and higher one, which Cuvier has 
termed the intermediate lobe. At the commencement of 
mastication, the dentine is first exposed upon the outer zig- 
zag ridge, and being bound by two parallel lines of ena- 
mel, a double crescent is produced, like that on the outer 
half of the tooth of a Ruminant quadruped ; but as masti- 
cation proceeds in the Paleothere, the second or internal 
crescent of enamel is soon obliterated. The field of den- 
tine is widened and bounded by the peripheral ridge of 
