337—160 INDIAN TERTIARY AND POST-TERTIARY VERTEBRATA. 
regarded as that of a male, and the British Museum specimen as that of a female. 
This is confirmed by the larger size of the cheek-teeth in the former. 
Comparisons . — In the following table the dimensions of the four specimens 
described above (taken in the same 
order) are 
compared with those of the 
mandibles 
of M. meganthereon and M. neogceus : 
: — 
M. meganthereon. 
M. sivalensis. 
M. neogaeus. 
Interval between condyle and canine 
5-53 (?) 
7-0 
Length of diastema ..... 
1-43 
1-47 (?) 
2-68 
§5pace occupied by cheek-teeth . . 
1-9 
2-2 
2-2 
2-03 
2-43 
2-73 
Depth of jaw in front of pm. 3 
1-18 
1-35 
115 
„ „ „ atm. 1 
1-2 
M8 
1-35 
1-36 
1-41 
1-57 
Transverse diameter of condyle 
1-6 
Length of pm. 3 
0-39 
0-4 (?) 
0-32 
0-37 
0-44 
0-33 
,,,,,, 4 
0-85 
0-84 
0-8 
0-94 
113 
Width „ „ 
(-•41 
0-4 
0-53 
Length ,, m. 1 
0-71 
0 98 
1-02 
0-9 
1-02 
114 
These dimensions indicate that M. sivalensis was intermediate in size between 
the other two species. The carnassial of the smallest specimen is about equal in size 
to that of a small tiger ; but is rather larger in the other specimens, in which the 
jaw is shorter than in the tiger : the animal was, therefore, probably intermediate in 
size between the tiger and jaguar, and had relatively large cheek-teeth. 
Compared with the species in the list on pages 156-7, the present species in 
respect of mandibular characters is distinguished from M. cultridcns by its inferior 
size ; by the lesser development of the coronoid process and the descending symphysial 
expansion ; the smaller pm. 3 ; and the more oblique direction of the lobes of pnEY. 
As the mandibles of the species marked Nos. 2, 3, 4, and 5 are unknown, comparisons 
are impossible. M. meganthereon is distinguished by its smaller size ; by the larger 
development of the coronoid process ; and by the more backward extension of the 
descending mandibular expansion, the posterior border of which has not such a 
sudden separation from the inferior border of the horizontal ramus : pm. ’3 apparently 
agrees in relative size with the corresponding tooth of M. sivalensis 1 ; but the hind 
talon of pm. 4 is less complex than in the latter. M. necator is distinguished by the 
absence of pm. 3 ; but the form of the symphysial expansion, and of the other 
cheek-teeth appears to be very similar in the two. M. palmidens is broadly 
distinguished by its inferior size, and the complex talons of pm. 3. M. neogceus , 
besides its superior size, differs by the relatively smaller size of its descending 
symphysial expansion ; but agrees in the proportionate size and structure of the cheek- 
teeth ; pm. 3 being, however, frequently somewhat smaller. The Siwalik jaw agrees 
with both the S. American species in its small coronoid process. 
It appears, therefore, judging from the characters of the mandible, that M. 
sivalensis is distinct from such of the described forms with which it can be compared ; 
but comes nearest in some respects to M. meganthereon , and in others to M. necator 
and M. neogceus ; the characters allying it with the latter being, as will be shown 
below, of the most importance. 
l In M. meganthereon this tooth is inserted by two fangs ; in the Siwalik form it may have either one or two. 
