13—154 
SlWALIK SELENODONT SUINA, ETC. 
referred to Hyopotamus, that it was at first considered doubtful whether the two could 
be even specifically separated. 
Mandible. — The assignation of their respective lower jaws to allied forms when 
there are two or more species of nearly the same size is always a matter of extreme 
difficulty and uncertainty, and in the present instance the reference must be 
considered purely provisional, or, indeed, merely as a guess. In plate XXY. there 
are represented three fragments of mandibles of large selenodont Suina, obtained 
from the Bhugdx hills in company with the foregoing specimen, which must evidently 
belong either to the present species or to Hyopotamus giganteus, described in the 
sequel. These three fragments, although agreeing in the size and structure of their 
teeth, show such differences in their shape that it is probable that they belong to at 
least two distinct species, one of which was furnished with a more slender mandible 
than the other. As it appears that the mandible of Anthracotherium is generally of a 
stouter type than that of Hyopotamus (compare plate XXI Y., figures la and 4), the 
stouter jaw is provisionally assigned to the present species. Of the two specimens 
showing the last true molar, the specimen represented in figure 1 has the greatest 
depth of j aw. It shows the hinder part of the last true molar, and a fragment of the 
horizontal ramus, with the commencement of the surface for the attachment of the 
masseter muscle. Its dimensions are as follows : — 
In. 
Depth at second column of molar . . . . . . I . . 3.22 
Greatest thickness . . . 1 - .5 
Width xif' last molar 1-2 
The inferior border exhibits the notch characteristic of Anthracotherium and its allies. 
In figure 3 of the same plate there is represented a fragment of a right ramus 
of the mandible showing the second true molar, in an intermediate stage of wear, 
and a portion of the much-worn first true molar. The dimensions of this specimen 
are as follows 3 ,^ 
In. 
Depth at hinder border of 2nd molar . 3-42 
Length of second molar ' 1-4 
Width of „ „ ... I , . . . . . . . , . 1-16 
It will be seen that this specimen is still deeper than the last, but it is possible 
that the two may have belonged to the two sexes of the same species. No further 
comparisons can be made with the materials available. The points distinguishing 
the specimen represented in figure 1 from that in figure 2 will be discussed with 
the description of the latter, under the head of Hyopotamus giganteus. 
Genus II. HYOPOTAMUS. 1 Owen. (1847). 
Ancodus. Pomel(1847). 
Botliriodon. Ayrnard (1848). 
Cyclogn a th us . -¥j Croiz. 
Tapinodon, Meyer., 
History aycd Characters . — This genus was established in 1847, by Professor Owen, 2 
on the evidence of certain molar teeth and jaws obtained by the late Marchioness of 
l From Inis, kws , a pig, and petamos, a river. 2 « Q,uar. Jour. Geol. Soc.,’ Vol. iv., p. 143, et scq. 
