21—162 
SIWALIK SELENODONT SUINA, ETC. 
the tooth of A. hyopotamoides fleft side of figure ) the middle vertical ridge is very- 
large and wide, and is so largely developed that if a rod he laid on the external 
surface of this column, it will rest on this median ridge, as well as on the lateral 
borders of the surface. In the corresponding part of the tooth under consideration 
fright side of woodeutj , the median ridge is greatly depressed below the plane of the 
lateral borders of the external surface of the column : this depression is so extensive 
that a rod placed as before will be raised more than a third of an inch above the 
median ridge. The central part of the external surface of the first column is similarly 
depressed in this tooth, and elevated in the tooth of A. hyopotamoides , but the damaged 
condition of this part in all the three specimens forbids a closer comparison. The 
tooth figured in the woodcut agrees in all respects with the specimen represented in 
plate XXIV, figure 3, except that the £ cingulum ’ in the former is rather less fully 
developed than in the latter. 
The foregoing comparisons lead to the conclusion, improbable as it at first sight 
appears, that the two molars last described, although agreeing in size, are so different 
from the molar of Anthracotherium hyopotamoides that it seems difficult to refer them to 
the same species. A comparison of these two teeth with the tooth represented in 
plate XXIII, figure 4, will, moreover, lead to the conclusion that the three teeth 
belong to the same genus of animal, and as it was shown that the specimen above- 
mentioned could not be separated from the genus Eyopotamus, it will be necessary to 
refer, provisionally, the two larger teeth to the same genus. As no named species 
has teeth as large as these specimens, if the generic determination be correct, it is 
clear that these specimens must belong to a new species, for which the name of 
II. gig anteus is proposed. 
The close similarity existing between the upper molars of Eyopotamus gig anteus 
and those of Anthracotherium hyopotamoides , and the gradual transition in respect of 
the character of the teeth thus effected- between the two genera, seems to render it 
highly probable that there may be a similar transition in respect of the cranial 
characters, and that eventually the two genera will have to be fused together, though 
it has not been considered advisable to adopt this course on the evidence of the 
present inadequate materials. Should this course be eventually considered advisable 
the older name Anthracotherium must stand for the extended genus, and the family 
name Anthracotheridce entirely replace the name Eyopotamidce, the latter course having 
been adopted in the present memoir. The transition from the typical form of one 
genus to that of the other is exhibited in the following list, which, however, does 
include all the species. 
Anthracotherium magnum (type) 
. alsaticum. 
' — — silistrense.' 
— — cuvieri. 
hyopotamoides. 
