22 POEBROTHERIUM. 
Its extremity is broken in the specimen. The symphysis also is broken away, but 
it appears to have commenced from behind about four lines in advance of the second 
premolar, and the anterior mental foramen is situated just above this portion of it. 
Dentition.—I think it probable that the permanent dentition of Poebrotherium 
was equal to the following formula :— 
a. Ua é. Lebeeue p.m. lee m. pag in 38. 
AR OO UR 4 4 3.3 
In the specimen, the symphysis with its teeth is broken away; and a portion 
only apparently of the upper canine alveolus remains. 
Superior Molars—The upper teeth, in the specimen, consist of the three per- 
manent true molars, fully protruded, and the three temporary molars, forming 
together a closed row, and separated from this by a hiatus with an acute concave 
margin about four lines long, is, what I suspect to be, the first permanent premolar, 
which had no predecessor. (Figs. 1, 3.) 
The permanent true molars resemble those of the Musks, but their constituent 
lobes possess much less prominent summits. ‘The inner lobes also are less angular, 
but more convex internally, and the outer lobes are much less prominent in the 
same direction. The outer lobes of each true molar, in the Musks, are separated 
by a narrow cleft, but in Poebrotherium they are separated only by a longitudinal 
ridge, which is the most prominent of those existing externally. The median 
ridge of each lobe externally is the most prominent and convex in the Musks, 
but is relatively narrow in Poebrotherium, and the intervening spaces are more flat 
in this genus. 
In the specimen under consideration, the last molar had been but a short time 
fully protruded, the enamel being worn only from the summit of its postero-internal 
lobe, and remaining nearly intact upon the postero-external. The summits of all 
the other lobes of the true molars present narrow tracts of exposed dentine sur- 
rounding the interlobular pits of enamel. 
The temporary molars, also, have a very great resemblance to those of the Musks. 
The last of the series is like the permanent true molars, and in the specimen the 
enamel has been worn from the masticating surface, except a small crescentic islet 
between the posterior pair of lobes. 
The second temporary premolar in the specimen has its enamelled triturating 
surface obliterated, and in its present condition is constituted by a wide posterior 
lobe, the result of the confluence of an original transverse pair, and a narrower 
anterior lobe with a pyramidal summit, which does not distinctly appear to be 
formed from the association of an antero-posterior pair, such as exists in the corres- 
ponding tooth of the Musks. Externally this tooth presents three convex promi- 
nences, separated by concave depressions. 
The first temporary premolar has a simple, broad, oblong, trenchant crown, which 
is most prominent at its anterior part. It is convex externally, and the enamel 
internally is worn off in a sloping manner. 
The first permanent premolar, which, as before observed, is removed from the 
others by a hiatus, has a simple oblong, trenchant crown like that last described, 
