part!.] Lijdehker: Further Notices of Siwalik Mammalia. 45 
coner ”; if the description of that tooth be compared with that of the corre¬ 
sponding lower tooth noticed above, it will be seen that the two agree precisely, 
except that one is the reverse of the other, as is always the case in upper and 
lower molars. I have therefore no doubt but that these new jaws belong to M. 
pandionis, which was consequently a species proA-ided with a long spatulate 
mandible, and of which the male carried inferior tusks. 
The interest of this discovery of M. pandionis in the Siwaliks is very great; 
the other known teeth are said to have been obtained from the Deccan from 
deposits supposed by Falconer* to be of pliocene age ; wherever they came from, 
it is now probable that they belong to the same period as that in which lived the 
other animals of the Siwalik fauna. In cataloguing the fossil Frohosoidia in the 
Indian Museum, I have lately come across a last milk-molar of a trilophodont 
Mastodon from Perim Island which seems undoubtedly to belong to the same 
species. 
In treating of M. pandionis at page 124 of the first volume of the “ Paleon¬ 
tological Memoirs, ” Dr. Falconer remarks on the great similarity of the general 
plan of the teeth of M. pandionis and M. angustidens, the plan of the former 
being, however, rather the more complex of the two. It is interesting to observe 
how this .similarity of plan in the structure of the teeth extends into as much 
as we know of the osteology of the two animals; thus the newly discovered 
specimens reveal to us that both the species were furnished with a long spatulate 
symphysis to the mandible, tuskless in the female, but in the male provided with 
a pair of relatively large and slightly'’curved tusks. From this similarity in struc¬ 
ture we may, I think, infer that these two sjiecies of Mastodon were very closely 
related to one another, and that it is not impossible that at no relatively distant 
epoch they must have had a common parentage. One very important difference, 
however, exists in the structure of the teeth of the two species, which is that in 
ill. pandionis (though this is not mentioned in Falconer’s specimen) there is a 
large quantity of cement in the valleys, which is entirely wanting in the molars 
of M. angustidens. 
Mastodon peeimensis, Falc. & Cant. 
Two very interesting points in relation to the dentition of this species are 
shewn among Mr. Theobald’s last collection; one of them is, that this species, 
Uke M. latidens, was provided with an ultimate upper premolar, and the other 
that the species carried tusks in the mandible. The specimen proving the ex¬ 
istence of an upper premolar consists of a portion of the left maxilla con¬ 
taining two teeth ; the hinder of these teeth is 4^ inches in length, carries four 
transverse ridges, and small fore-and-aft talons; the anterior tooth has not yet 
come into wear, being only in germ, and having its masticating surface on a 
level with the base of the crown of the hinder tooth, w^hich proves it to be a 
premolar, which has only just displaced the milk-molar which it has succeeded. 
1 Pal. Mem., Tol. II, table, p. 14. 
