SIWALIK AND NARBADA PROBOSCIDIA. 
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normal tetralophodont law, and their ridge-formula may accordingly l)e expressed 
as follows ; — 
Milk-molars 
Falconer’s conjectural ridge-formula of the milk-molars of the species noticed above 
is consequently incorrect. With the evidence of the specimens figured in the “ Fauna 
Antiqua Sivalensis,” and described in the “ Catalogue of the Fossil Vertehrata in 
the Museum of the Asiatic Society of Bengal” before him, it appears, to say the 
least, very curious that Falconer should have put forw^ard the pentalophodont 
formula for the milk-molars of M. sivalensis. The only possible exception to this 
rule would be the case of a lower jaw in the Museum of the College of Surgeons 
referred to by Falconer in a note to the description of Plate XXXVII of the 
“ Fauna Antiqua Sivalensis.” It is, however, probable that the tooth there considered 
as the last milk-molar is really the first true molar, as we shall see below. 
First upper true molar. — At page 47 of the “ Catalogue of the Fossil Vertehrata 
in the Asiatic Society of Bengal,” Dr. Falconer shortly notices a palate of M. siva- 
lensis containing the last milk-molar and the first true molar (No. 13). Tlie position 
of these teeth is determined from their identity with the two corresponding teeth 
in the jaw which contains the third upper milk-molar figured in Plate XLI, fig. 
2, of this memoir. In the latter jaw, as already said, the first true molar is imperfect, 
hut in the former it is complete, and is shown to have four ridges and a hind- 
talon. It has a length of 4’ 2 inches and a width of 2*4 inches. I have not figured 
this tooth, because it is a good deal damaged and chipped. I cannot find any 
specimen of a five-ridged tooth w''hich I can certainly refer to the first true molar. 
The characters of the first upper true molar are so exactly similar to those of the 
milk-molars that I have not thought it necessary to give any description of that 
tooth. 
First lower true mslar . — -To the description of Plate XXXVII of the “ Fauna 
Antiqua Sivalensis” Dr. Falconer adds a note (1) in which he describes a lower jaw' 
of Mastodon sivalensis in the College of Surgeons which contains a complete six ridg- 
ed tooth followed by a larger incomplete tooth. The former has a length of 4’ 2 inches 
and a width of 2'4 inches. The width of this tooth is considerably greater than that 
of the third lower milk-molar figured here, from which fact, coupled with its high 
ridge-formula, I think that this tooth is probably the first true molar and not the 
last milk-molar, as it is considered by Falconer. 
I cannot fin d any other complete tooth which I can certainly class as the first 
lower true molar of this species, though I tlunk it probable that specimens wfill 
eventually he found with either four or five ridges. 
Second upper true molar. — In fig. 4 of Plate XXXVI of the “ Fauna An- 
tiqua Sivalensis ” there is figured a tooth which seems evidently to be the second 
upper true molar of M. sivalensis, and w^hich seems to have four ridges and a 
large hind-talon. Its length is 5*6 inches, and its width 2*9 inches. In fig. 5 
