96—62 INDIAN TERTIARY AND POST-TERTIARY VERTEBRATA. 
might have been m. 1 of the same form. As these teeth do not appear to present 
any characters, except tliat of size, by which they can be distinguished from fig. 12, 
it is obvious that it is impossible to say whether fig. 1 1 be m. 2 of the smaller or m. 1 
of the larger form. The small teetli are almost indistinguishable from specimens in 
the Indian Museum from Grermany, which, on the authority of Klipstein, are 
referred to the ill-defined 77. medium. 
In figures 9 and 15 of the same plate there are represented two last upper 
premolars of a pig-like animal, belonging to opposite sides of the jaw, which may 
probably be referred to the present genus. The smaller specimen agrees in relative 
size with fig. 13, and the larger with fig. 6. The two teeth agree very closely in 
structure, although the smaller one has a more distinctly developed cingulum : they 
resemble to a great extent the corresponding tooth of II. soemmeringi ; but are 
distinguished by the two outer columns being less equal in size, as well as by the 
greater development of the transverse ridges connecting the inner columns with the 
two outer columns. In II. loaterhousi., H. tgjms, and most other species, these 
connecting ridges are scarcely developed at all. 
Loiver molars. — In figures 7, 8, of plate XII. there are represented two right 
lower true molars in a well-worn condition, which agree with those of the present 
genus. The one represented in fig. 8 may from its size be regarded as m. 1, and 
agrees in relative size with the small upper teeth represented in figs. 13, 14. The 
second specimen may be regarded either as m. 2 of the same form, or as m. i of the 
larger form represented in figs. 6 and 12. Both these teeth agree in general 
proportions, and, as far as can be seen, in structure, with the lower molars of II. 
soemmeringi : the smaller specimen agreeing with m. 1 • of a small individual of that 
species figured by Peters'; and the larger with m. 2 of the same specimen, and also 
with hTT of a larger individual figured by the same writer.- In figure 16 of the 
same plate there is represented a fragment of the right ramus of a mandible 
containing mm. 4 and m. 1 ; both in an unworn condition. The true molar is of the 
same size as the specimen rei^resented in fig. 8 : it is of smaller size, and the columns 
are of a more simple structure than in the corresponding tooth of Bus hysudricus 
(pi. VIIL, fig. 8). 
Distinctness and affinities. — With the materials at present available it is impossible 
to say whether the larger and smaller teeth noticed above belong to one or two 
species. Their similarity in structure, coupled with the variation in the size of the 
teeth referred to 77. soemmeringi (assuming all of them to be rightly associated), seems, 
however, to be in favour of the former alternative. It is also impossible to say 
whether such species belonged to Dyotherium or to one of the allied American 
genera ; but in the absence of any evidence to the contrary it may, from the 
resemblance of the teeth to those of 77. soemmeringi be, at least provisionally, referred 
to that genus. The larger specimens indicate a species of the size of the larger 
1 Op. cit., pi. II., fig. 6. 
2 Ibid, fig. 7. 
