part 2 .] LydekJcer : New or rare Mammals from the Siwaliks. 
81 
fied into more specialised groups, or died out, or reverted to the more generalised bunodont 
type. 
The resemblance in structure between Hippopotamus and Merycopotamus, whether 
the above explanation be fully accepted or not, clearly points to some closer connection 
between the Selenodonla and Bunodonta than appears from Kowalevsky’s table. In that table 
the term Bunodonta is used as equivalent to the Suina ; but it appears to me much more 
natural to use the latter term in its older and wider sense as comprehending the pigs, 
the hippopotamoids, the hyopotamoids, and the anoplotherioids, since all these animals 
are related in many essential parts of structure; the two former groups will belong to 
the smaller division of Suina Bunodonta, and the two latter to the second similar 
group of Suina Selenodonta ; from which latter the more specialised Selenodonla have been 
developed as a lateral off-shoot. 
lIirroroTAiioDON Sivalense, n. gen., nobis. 
The specimen for which I propose the above new generic name consists of a portion of 
a left maxilla of an animal allied to Hippopotamus, but which cannot be referred to that 
or any other known genus. The specimen has been for some time in the Indian Museum, 
and was collected by Mr. Theobald near the village of Asnot, in the Punjab, from upper 
Siwalik strata. The fragment shows the commencement of the zygomatic arch, and some 
portion of one-half of the palate; two nearly complete teeth, and a fragment of a third 
are preserved. The three teeth appear to be the three true molars; the, last of these, being 
the most complete, is here selected for description. 
This tooth has a nearly square crown, which is produced into four cones or columns, 
one placed at each angle; these columns are separated by a deep but narrow cruciform 
valley; between the four chief columns there is a small fifth column; while still smaller 
accessory columns occupy each of the four outer extremities of the cruciform valley; a 
crenulated cingulum occupies the fore and aft extremities of the crown. The main columns 
are semi-cylindrical in shape, and have infoldings of enamel from in front and behind, so 
that their worn dentine surfaces have somewhat of a trefoil shape, though this is not 
so marked as in Hippopotamus. The last tooth' is placed immediately below the anterior- 
root of the zygoma, as in the pig. The dimensions of the two last molars are as follows :— 
Length of last molar 
Breadth of ditto 
Height of crown of last molar 
Length of pen ultimate molar 
Breadth of ditto 
1-4 
1'29 
IX 
105 
The teeth are nearest to those of Hippopotamus, but are distinguished by the presence 
of the central fifth column, by the relative size of the other four accessory columns, by the 
crown being much lower, by the greater depth of the transverse valley, which extends to the 
base of the crown, by the form of the worn dentine surfaces, and of the cingulum, and 
lastly, by the position of the ultimate molar below the anterior zygomatic root. 
The teeth of this new genus have no close resemblance to the molars of Tetraeonodon ; 
those of the latter genus, among other distinctive points, have wide open valleys, cylindri- 
form columns, and no cingulum. 
