TEETH OF RHINOCEROS FROM ILFORD. 233
papers by himself and Mr. J. P. Johnson which have appeared
in the Essex Naturalist. It is a detached fourth premolar of
the left upper jaw. The transverse valley is completely isolated
through wear and into it, from the posterior barrel, is projected
a strongly developed bifid crochet. The outer wall gives off two
very small combing plates, one of which is parallel to and just
above the bifid crochet. The other is given off in a line with the
anterior external angle of the tooth, converging towards the first
and the crochet at a right angle. The posterior valley is not yet
isolated, and the cap of enamel which arises from its inner wall,
and which passes over the hind barrel and so into the inner wall
of the tooth is still in great measure intact (fig. 2). There is a
well marked basal bourrelet passing right round the anterior
barrel. This starts from near the grinding surface a little
inwards from the anterior angle; from this point it gradually
sinks until the inner extremity of the anterior barrel is reached,
from whence it rapidly rises up again ending off at the inner and
forward rim of the enamel cap before spoken of. The dimensions
of this tooth are :—
Antero-posterior length measured along outer surface at base .. 1.7 inches
,, ,, ,, inner ,, .. 1.25 ,,
Antero-transverse width at base .. .. .. 2.47 ,,
Postero- ,, ,, ,, .. .. .. 2.2 ,,
Height of crown at junction of anterior and posterior barrels .. 1.4 ,,
,, ,, anterior outer angle .. .. .. 1.88 ,,
I have referred this specimen to R. leptorhinus, Cuvier,
pro parte ( = R. megarhinus, De Christol). The point to which I
wish to direct special attention is the remarkable state of wear
and the figure will give a much better idea of the characters
described here than any mere verbal description. In all known
species of Rhinoceros, either fossil or recent, the small posterior
valley is the first to be isolated into a fossette by the detrition of
the tooth. This arises from the fact that while the entrance to
the posterior valley is comparatively shallow, not cutting deeply
into the body of the tooth, being from this cause soon obliterated,
the entrance to the transverse valley forms a much, deeper cleft
separating the barrels and consequently remaining for a propor-
tionally longer period intact. But in this specimen it is the
transverse valley which has been isolated first, the posterior
valley having its entrance still intact though cutting into the
tooth no deeper than usual. This malformation appears to me