20 
INDIAN TERTIARY AND POST-TERTIARY VERTEBRATA. 
The transverse ridges are divided by a fissure traversing the long axis of the crown 
into inner and outer columns, which have a tendency to an alternate arrangement. 
Each of the valleys dividing the ridges is blocked by adarge accessory column (a), 
placed on the posterior aspect of the transverse ridges, and extending across the 
median longitudinal fissure. When slightly more worn the dentine surface of each 
of these accessory columns would coalesce with that of the outer column immediately 
in front of it, and produce rudely trefoil-shaped dentine islets ; and it is evident 
that in a somewhat earlier stage of wear the antero-internal angle of each of the 
outer columns (b) would have formed a separate smaller anterior accessory column. 
At the outer extremity of each of the transverse valleys there is a low, blunt 
tubercle ; the separate tubercles being connected by a cingulum. The transverse 
valleys are comparatively wide at their extremities so that the ridges are not in 
contact. There is no trace of any cement. 
Compared with the corresponding tooth of the Siwalik M. pandionis,^ the present 
specimen will be found to differ very widely. In the first place, it is of considerably 
smaller size ; while the ridges are lower, and the hind talon is single in place of 
double : the anterior talon seems also to have been smaller. . The accessory columns 
of M. pandionis are much more numerous, being wedged in between the main 
columns of the ridges, and blocking the transverse valleys to a much greater extent 
than in the present specimen. The columns composing the transverse ridges in 
M. pandionis are moreover in close contact at their bases, so, that the valleys become 
extremely narrow. The blunt tubercles occurring at the outer extremities of the 
transverse valleys of the present specimen are not distinctly developed in M. 
pandionis ; and the worn dentine surfaces of, the latter have no tendency to assume a 
trefoil shape. Finally, cement is present in large quantities in the molar of 
M. pandionis. 
The corresponding molar of 3£. falconeri.^ the other Siwalik trilophodon, is 
unknown, but as it will be shown below that the other teeth of the Biigti mastodon 
are different, the present specimen cannot be referred to that species. 
Compared with the last lower molar of M. angustidens the present specimen 
agrees very closely. A tooth of that species figured by H. von Meyeff is of precisely 
the same size, and has the same general contour of the crown, with the exceiDtion 
that the borders of the crown are less curved : and in other European specimens''^ 
these borders are still less curved. The arrangement of the ridges, and the 
form of the transverse valleys is exactly the same in the two ; and there are the 
same blunt tubercles at the outer extremities of the transverse valleys. The hind 
talon of the European tooth is, however, more detached ; and consists of only one 
column. The most important difference between the two teeth consists in the 
1 Vol. I., pi. XXXIV., fig. 2 ; XXXV,. fig. 4 : the second of these specimens agrees exactly in its degxee of wear with 
the specimen under consideration, and from belonging to the same side, is very favourable for comparison. 
2 “ Palaontographica,” vol. XVII., pi. VII., figs. 3 and 4 . 
3 Vacek, ‘ Abhand. k. k. geol. Eeich.,’ vol. VII., pt. 4, pi. IV., fig. 2. 
