241—60 
SIWALIK AND NilRBADA PROBOSCIDIA. 
of the larger tooth. The relatively large size of the premolar shows that that tooth 
must be the last of the premolar series, and consequently that the larger tooth must 
he the first true molar. 
The premolar has two ridges, which are considerably higher than those of the 
corresponding tooth of Mastodon latidens described above (Plate XXXVII, fig. 6) ; 
the ridges are crowned by distinct cusps. There are weU developed fore-and-aft 
talons. The dimensions of the two teeth are as follows : — 
Length of premolar . . . . ... . • . . 2-15 
Width of ditto .......... 1’8 
Height of first ridge of ditto ......... 1'3 
Length of true molar ......... 4*2 
Width of ditto .......... 2'4 
Height of second ridge of ditto ........ 1‘7 
Comparisons. — The first true molar in the specimen described above • differs 
entirely from the molars of Mastodon latidens, which is the only Indian TetralopJio- 
don which we have yet described, and it will also he shown to differ from the molars of 
M. sivalensis which are described below. There, therefore, only remains M.perimen- 
sis to which the specimen can belong, and we find that the characters of the tooth 
agree precisely with those of the molars of that species noticed above, and I have 
consequently referred the specimen to that species. In figs. 3 and 4 of Plate IX 
of the first volume of the “ Palaeontological Memoirs,” a specimen of the same tooth 
of M. perimensis from Perim Island is figured on a small scale, in profile and plan. 
That tooth was named by Dr. Palconer, and is now in the collection of the Indian 
Museum. It is rather less worn than the specimen figured here, but agrees exactly, 
in all its characters, with the exception of being somewhat larger. The length 
of the Perim Island specimen is 4‘5 inches, and its width 2-7. It is probable that 
the latter belonged to a male, while tte Punjab specimen belonged to a female 
individual. 
Comparison with M. longirostris. — The molars of M. perimensis present, at first 
sight, a very striking resemblance to the molars of the European M. longirostris,^ 
though a closer examination shows certain differences between the two. Wq have 
already seen that in the upper molars of M. perimensis, only the inner columns of 
the ridges carry accessory tubercles next the longitudinal cleft, and that conse- 
quently these columns alone present during detrition a trefoil-shaped surface of 
dentine, while the outer columns present an oblong surface. In the molars of Masto- 
don longirostris, on the other hand, both the inner and outer columns of the ridges de- 
velope accessory tubercles next the cleft, and both in consequence wear into trefoils, as 
is shown in Kaup’s figures. The trefoil of the outer column, however, does not appear 
till the inner is partly disappearing, owing to the lesser height of the accessory tuber- 
cles of the former. In consequence of this a molar of M. longirostris, when slightly 
worn, carries a trefoil dentine-surface on the inner ridge, and an oblong one on the 
* See Kaup : “ Ossements Fossiles du Museum de Darmstadt,” PI. XVI. 
