SIWALIK AND NAEBADA PEOBOSCIDIA. 
63—244 
lower ridges than the corresponding tooth of M. perimensis. A comparison of the 
two figures will, however, show that in general characters the two teeth are exceed- 
ingly alike. The European tooth is distinguished, in addition to the difference in 
relative size, by diminishing less rapidly in width posteriorly, and by the consequent 
greater size of the fifth ridge and hind-talon : the columns of the ridges are also 
somewhat less distinctly separate than in M. perimensis. 
Second lower true molar. — Of the lower dentition of Mastodon perimensis the 
first tooth with which I am acquainted is the second true molar, of which a speci- 
men is represented in fig. 1 of Plate XLI, collected by Mr. Theobald in the Pun- 
jab. The tooth has a concave profile, showing that it must belong to the lower 
jaw ; the ridges present a concave surface to the broken end, showing that this must 
be the posterior extremity, and that the tooth must consequently belong to the left 
side of the jaw, since the median cleft is nearest the upper border of the figure. 
Prom its size the tooth is inferred to be the second of the true molar series. The 
crown is slightly narrower in front than behind and carries four transverse ridges, 
(of which the last is broken), and a large posterior talon (also broken) ; a ledge on 
the first ridge represents an anterior talon. The ridges are high, and are divided by 
a median cleft, which, however, is not so distinct as in the upper molars. The sum- 
mit of each of the four ridges (all of which are quite unworn in the specimen) ter- 
minates in about six blunt cusps ; the portion of each ridge placed externally to the 
median cleft (lower half of figure) would wear into trefoils, owing to the presence of 
accessory tubercles in the valleys, along the median line of the tooth, which block the 
vaUeys. Cement is present in the valleys. The length of this tooth is 5'1 inches, and 
its width 2-8 inches. The size of this tooth agrees, therefore, with that of the 
second upper true molar from the Punjab, wliich has been described above ; from 
this, and from the presence of a large hind- talon in both, the lower molar has been 
considered as the second of that series. The somewhat greater simplicity in struc- 
ture of this lower molar, as compared with the corresponding upper tooth, is similar 
to that which occurs in M. longirostris. A well-worn specimen of the second left 
lower true molar of M. perimensis from Perim Island is represented in fig. 10 of 
Plate XXXI of the “ Pauna Antiqua Sivalensis.” That tooth has a length of 4’ 8 
inches, and a width of 2 ’6 inches. Allowing for the one tooth being a germ, and the 
other much worn, the two teeth in question seem to have the same form : in 
Palconer’s specimen the hind- talon is seen to consist of two large cones, only one of 
which remains in Mr. Theobald’s specimen. 
Last lower true molar. — A specimen of the last lower true molar of the present 
species from Perim Island is represented in fig. 11 of the last quoted plate of the 
“Pauna Antiqua Sivalensis.” The tooth carries five ridges and a large hind-talon, 
and agrees in all essential characters with the last upper molar figured in the plates 
accompanying this memoir. The length of the lower molar is 8’4 inches, and its 
greatest width 3'5 inches. A very similar tooth, collected by Mr. Theobald, is in 
the collection of the Indian Museum, but I have not thought it necessary to give a 
