SIWALIK AND NAEBADA PEOBOSCIDIA. 93—274 
the parieto-frontal region in much the same manner as in the living elephants, and 
by the consequently great width of the temporal fossse. 
Less typical skulls of S. insignis, as the specimen represented in fig. 1 of 
Plate XVII of the “Pauna Antiqua Sivalensis,” and another in the Indian 
Museum, have a somewhat greater vertical development of the parieto-frontals. 
The temporal fossa in these skulls is, however, still very narrow. Young skulls of 
the species, however, have the fronto-parietal region well developed, as in S. ganesa 
(P. A. S., Plate XVIII, figs. 1, 2, 3), and it appears, therefore, that the aborted 
frontal region of N. insignis is only a characteristic of the adult. 
That the one large cranium ascribed to Stegodon ganesa is not a single abnor- 
mality is proved by the existence of another very similar cranium, with the tusks 
broken off, obtained by Mr. Theobald in the Punjab, and now in the Indian Museum. 
This cranium was described by myself in the “ Eecords,”^ under the name of 
ganesa. The resemblance of this cranium to that named S. ganesa in the ‘‘ Pauna 
Antiqua Sivalensis” is so close that I have thought it unnecessary to give a figure 
of it, almost the only difference between the two being that the former has the 
frontal region somewhat hollowed mesially in place of being quite flat as in the 
latter. 
It thus appears that there are two very distinct forms of adult crania of 8te- 
godons, which have the same dentition, and which in the young state also appear to 
be indistinguishable. On the whole, I now think it very probable that S. ganesa 
may be merely a very well marked race of 8. insignis,, or, in other words, may be 
a species in process of evolution. The adult race is, however, so well marked 
and so distinct that I prefer to continue to apply to it a separate specific name, with 
the above proviso. 
On page 31 of the tenth volume of the “ Eecords,” I have noticed a speci- 
men of a huge tusk of an elephant from the Narbada valley, which from its size 
and form seems to belong to 8, ganesa. Prom the same deposits teeth which agree 
with those of 8. insignis have been obtained, but no specimen of the cranium, and 
it is therefore not certain whether they might not also belong to 8. ganesa. The 
discovery of the cranium of either of the 8tegodons in the Narbada valley will be a 
matter of great interest, as we shall then see whether they had undergone any 
further differentiation in the period immediately succeeding that of the Siwaliks. I 
have already commented upon the similarity of certain of the molars of some of 
the Indian Mastodons as bearing upon the case of 8. insignis and 8. ganesa^ in 
which no distinction can be found in the molars.^ 
1 Eec. Geol. Surv. of India, Vol. IX, p. 42. 
2 It may be mentioned that the molars of two well defined species of Himalayan marmots {Arctomys caudatus 
and A. himalayanus) are absolutely indistinguishable, and if found in the fossil state would be referred to one species. 
