249- 68 
SIWALIK AND NARBADA PROBOSCIDIA. 
TetralopJiodons. — In a subsequent paper communicated (but not then published) 
to the Geological Society of London in June 1857/ Dr. Falconer^ says : “ In the 
preceding part, when discussing the conditions of the ' ridge-formula ’ in Trilophodon 
and Tetralopliodon, it was stated that while the penultimate milk-molar always 
presents one ridge less than the intermediate molars, the last true molar presents 
one ridge more. Conformably, the last true molar in M. sivalemis presents six 
ridges, besides the hind ‘ talon,’ thus maintaining throughout, so far as the denti- 
tion is known, the numerical characters to be inferred from the ridge-formula, as 
ascertained in Trilophodon and Tetralophodon. I consider it suflB.cient, on the 
present occasion, to caU attention to this as a point of some interest and importance 
in the systematic and palaeontological relations of the Proboscidian family, in 
reference to the indications they present of an order of successive serial develop- 
ment, without entering in detail upon the evidence in support of the view here 
taken. That the species is a distinct form is abundantly borne out by the marked 
characters of the skull, independently of the strong dental characters. The ridge- 
formula for the true molars in Mastodon sivalensis is inferred to be — 
5+5+6 
5+5+(6— 7) 
and when the dentition is fuUy made out, it is anticipated that the complete ridge- 
formula will be nearly thus — 
Milk-molars. 
True molars, 
5+5+6 
5+5+(6— 7).” 
2+4+5 
2+4+5 
It thus appears that in his last notice. Dr. Falconer considered M. sivalensis 
to have a complete pentalophodont ridge-formula. 
In Plates XXXII and XXXIII of the “ Fauna Antiqua Sivalensis” a figure of 
a fairly complete cranium of the species is given, while in Plates XXXIV to XXXIX 
of the same work a considerable series of the teeth are figm^ed. From these figures 
and from various notes by Dr. Falconer, we gather that the molars of this species 
are characterized by being narrow, and with complex crowns, on which the columns 
of the ridges are placed alternately so as to completely block the valleys. The 
columns are tall, and when worn present irregularly shaped discs of dentine, 
and there is no cement. The mandible is represented in fig. 1 of Plate XXXV 
of the “Fauna Antiqua Sivalensis” and is characterized by a very short spout- 
like symphysis. 
First loiver milk-molar. — I cannot find any specimen of the first upper milk- 
molar of M. sivalensis, and the first tooth we have, therefore, to consider, is the first 
lower milk-molar, a specimen of which is contained in each of two specimens of the 
* Pal. Mem., Vol. II, p, 1. 
* Ihid, p. 87. 
