108 



FAUNA ANTIQUA SIVALENSIS. 



cast of the Darmstadt specimen, also figured bj^Kaup (PI. XVI. 

 fig. 1), but first described by Von Meyer, under the name of 

 M. Arvernensis. These specimens — the foi-mer belonging to 

 the right and the latter to the left side of the jaw — are very 

 nearly of the same age. ^ 



* * * * * -jf * 



We now get out of the true Mastodons, and the numerical 

 definition of the crown ridges of the intermediate molars 

 becomes gradually more and more irregular. Instead of 

 characterizing groups of species, as has been shown to hold 

 good with respect to the ternary and quaternary divisions, 

 the next ascertained numerical increments become distinctive 

 marks of individual species only ; and as the cypher in- 

 creases everything like correspondence between consecutive 

 teeth ceases, the number of ridges augmenting with the age 

 of the tooth, till at last they become indefinite. 



The next numerical formula after the ternary and quater- 

 nary might be expected to be quinary, in the ridges of the 

 last milk molar and the first and second true molars ; but the 

 number five is not met ivith in these teeth in any hioivn species. 

 There is an abrupt transition from four to six, which occurs 

 in Elephas Gliftii, the species which, in our view, constitutes 

 the first of the elephants, as distingaiished from Mastodon, 

 and establishes the immediate passage between the two.^ 



The accessible materials for illustrating the dentition of 

 this species are limited, at present, to the last milk molar 

 and the three true molars of the upper jaw, and the last 

 molar of the lower. The si:)ecimens which fru-nish these are 

 all derived from the kingdom of Ava. The last milk molar 

 is shown in a palate specimen along with the anterior portion 

 of the first true molar, brought by Colonel Burney from the 

 banks of the Irrawaddi, and i^resented by him to the British 

 Museum.^ But the crown is worn down to the common base 

 of enamel, and the number of ridges does not admit of being 

 distinctly made out. The first true molar is beautifully 

 shown in fig. 6 of Plate XXXIX. of Mr. CHffc's memoir in the 

 ' Geological Transactions.' It is a very broad rectangular 

 tooth, having the crown divided into six ridges, with a small 

 heel ridge. The ridges are continuously transverse, as in 

 the plates of the true elephants, with no indication of the 

 longitudinal furrow which, in all the true Mastodons, divides 

 the crown along the axis into two halves.'' 



' There is a deficiency here in the Mastodon Sivalensis indicated a Penta- 



Maniiscript, but further remarks on lophodon type. See rol. ii. — [Ed.] 

 M. lougirostris and M. Arvernensis viiW ^ See Fauna Antiq. Sival. pi. xxx. figs, 



be found in vol. ii. — [Ed.] 1, 2, and 3 ; and also Appendix.— [Ed.] 



2 This was written in 1846. Dr. Fal- ■• The Manuscript ends here.— [Ed.] 

 coner subsequently determined that 



