88—54 INDIAN TERTIARY AND POST-TERTIARY VERTEBRATA. 
collected by Mr. Theobald in the Punjab. In this specimen the teeth are still more 
worn ; m. 2 being reduced to a plain surface of dentine, and m. 3 about half worn. 
There is another very similar specimen in the Indian Museum (No. B. G7), from the 
same locality. The following table gives the 
taken in the same order : — 
dimensions of these three specimens. 
Length of m. 2 
0-9 
0-88 
0-77 
Width ,,,,,, 
0-89 
0-86 
0-74 
Length „ „ 3 
1-48 
1-43 
1-22 
Width ,,,,,, 
0-99 
0-93 
0-79 
,, ,, intermolar space at m. 2 
1-36 
1-34 
These dimensions are so near to one another that all the specimens may be 
provisionally classed together, although it is not impossible that they may belong to 
more than one species. It will be seen from the figures that the talon of m. 3 is 
relatively short, and corresponds with that of the homologous tooth of S. titan 
(pi. VII., fig. 6) ; consisting in an early stage of wear (pi. XII., fig. 17) of a hinder 
portion (^), and a median column (a). The same figure shows the correspondence 
between the other portions of the tooth and the molar of S. titan. Thus there are 
in each tooth four main columns with three accessory columns (a, y, h) in the median 
line ; at a later stage of wear (pi. XII., fig. 21) the accessory median columns unite 
with the inner main columns (as is the case in Sus), and produce the complicated 
pattern characteristic of the genus. The difference between the molars of Hippohyus 
and Sus titan consists in the columns of the former being taller, more elongated 
antero-posteriorly, with their outer walls more flattened, and the foldings of the 
enamel much deeper ; by which means the valleys are made very deep, narrow, and 
sinuous. The molars of S. falconeri (pi. VII., fig. 5)' are in some respects intermediate 
between the two, and easily show the manner in which the transition has taken 
place. The third molar of the last-named species is widely distinguished by its very 
comjDlex talon ; and the columns of all the molar teeth have been more squeezed 
together, so that the valleys are to a great extent obliterated. 
3Iandible and lower dentition. — In plate LXXI., figs. 2, 3, 4, of the ‘‘F.A.S.h 
there are represented three fragments of the mandible and lower dentition of a pig- 
like animal, which from the structure of the teeth undoubtedly belongs to the 
present form. The first specimen shows mTd and a part of m. 2 ; the second m. 1 and 
nhV, the former much worn ; and the third the same teeth in a less worn condition : 
all three S 23 ecimens came from the Siwalik Hills, and are now in the British Museum. 
The following table shows the dimensions of their teeth, viz.-. — 
Length of m. 1 ....... 0'5 0'55 
Width ,,,,,, 0'45 
Length ,, ,, 2 I'O 0-85 
Width „ „ 0-63 
Length ,, ,, 3 1’45 
Width „ „ „ 0-73 
In plate XII., fig. 3, of the present volume there are represented the hinder cheek- 
teeth of the right ramus of a mandible collected by Mr. Theobald in the Siwaliks of 
1 In the upper molars of S. falconeri the letters /, g correspond to g, h in those of the present species. 
