1847.]| OWEN ON EXTINCT ANTHRACOTHERIOID QUADRUPEDS. 107 
site angles of those lobes, the Anthracotherium resembles, more than 
the Cheropotamus does, the homologous tooth of the Hyopotamus ; 
but the protuberance is relatively less, and the outer facets of the two 
outer lobes are, like those of the Cheropotamus, much more convex 
in Anthracotherium than in the Hyopotamus. Cuvier says, e. 9.; 
“La face externe de celles (‘ pointes’ ou lobes) qui regardent en de- 
hors est un peu plus bombée que la face interne de celles qui leur sont 
opposées ;” and he then adds, “‘ mais les faces par ou elles se regar- 
dent ont chacune une arréte saillante, irréguliére, quelquefois bifur- 
quée, qui les rendent anguleuses,’’—a differential character which 
strongly indicates the generic distinction of dnthracotherium from 
Hyopotamus. 
The two fossil upper grinders (last premolar and first true molar) 
of a small Pachyderm from the tertiary deposits on the banks of the 
Brahmputra river, Bengal, referred to the genus Anthracotherium by 
Mr. Pentland, under the name of Anthracotherium silistrense*, differ 
from those of the typical Anthracotherium of Cadibona in the outer 
facets of the two inner lobes being concave, whilst the opposite facets 
of the two outer lobes are convex ; and, as in Dichodon and Merycopo- 
tamus, there is no trace of a fifth lobe. In the convex protuberance 
at the outer side of the interspace between the two outer lobes, the 
Anthracotherium silistrense resembles the Hyopotamus ; but it differs 
therefrom both in the absence of the fifth lobe, and in the antero-pos- 
terior diameter of the tooth exceeding the transverse diameter. The 
antero-posteriorly extended crown of one of the premolars, which 
supports two transverse pairs of lobes and a fifth anterior lobe, still 
more decisively distinguishes the Indian fossil from the true dnthra- 
cotherium, and brings it nearer the allied genus Dichodon. The in- 
ferior molars figured by Mr. Pentland in the same plate (45. figs. 1 
& 13) also resemble those in the genus Dichodon, as well as the pre- 
sent genus Hyopotamus. 
The generic difference between Hyopotamus and Cheropotamus 
will be made manifest when we compare the dentition of their lower 
jaws. And this is the more important, because there is a bare possi- 
bility that the upper molars ascribed by Cuvier to the genus Chero- 
potamus, which he founded on dental characters of a lower jaw, may 
not have belonged to the same animal as that jaw; and M. de Blain- 
ville has in fact availed himself of the absence of absolute demon- 
stration to refuse assent to the conclusion which Cuvier, from the 
strongest evidence short of that which an entire skull of a Chero- 
potamus would have yielded, arrived at. 
In the height, the sharpness and the general form of its four prin- 
cipal lobes, the upper molars of the Merycopotamus, Falconer and: 
Cautley, described and figured in my ‘ Odontography+,’ more nearly 
resemble that of the Hyopotamus than do those of either Anthraco- 
therium or Cheropotamus ; but there is no fifth lobe (2) between the 
principal pair on the anterior side of the tooth{. The opposite 
* Geol. Trans. 2nd Series, t. ii. p. 392, pl. 45. figs. 2, 3, 4 & 5. 
T Pl. 140. fig. 8, and in Quart. Geol. Journ. vol. iv. pl. 4. fig. 7. 
} Its absence may be interpreted, homologically, either by supposing the 
