ELEPHANT AND MASTODON. 55 



to its length, and measuring one inch five lines, by one inch four 

 lines. 



Professor Owen also gives a figure of the hypothetical position 

 of the same tooth in the lower jaw, 1 the presence of which he 

 admits has not yet been established in the species. The accurate 

 determination of this point is of considerable systematic impor- 

 tance, as the occurrence of this premolar constitutes one of the two 

 characters upon which (failing those advanced by Cuvier) Pro- 

 fessor Owen founds his generic distinction between Mastodon and 

 Elephas. Had the tooth been observed in situ in the jaw as in 

 the Dax Specimen of M. a?igustidens t figured by Cuvier 

 and in the specimen of M. longirostris, figured by Kaup, its occa- 

 sional presence in the upper jaw of M. Ohioticus would have 

 been placed beyond doubt ; but the tooth described by Professor 

 Owen appears to have been a detached specimen, and no charac- 

 ters are attributed to it inconsistent with its being the first milk 

 molar of the upper jaw. In order to arrive at a certain deter- 

 mination of the point, we have been permitted to make a section 

 of a specimen consisting of the entire palate, of a young Mastodon 

 Ohioticus in the British Museum, containing the second and third 

 milk molars, with the first true molar protruded, and the second 

 true molar in germ. A section was made both along the palate, 

 and along the outside of the jaw ; but not a trace of a premolar 

 was visible, although the cranium was exactly of the age when a 

 premolar, if developed, ought to have been shown. A similar 

 negative result attended a corresponding section of a specimen 

 of the same age of the lower jaw. The only other evidence 

 which could establish the case would be the finding of an unworn 

 tooth in front of the third milk molar. But, so far as we are aware, 

 no instance of this sort has been recorded, notwithstanding the 

 great number of young specimens which have been described by 

 different observers ; and the result of the whole evidence at present 

 is, that, ordinarily, the premolars are entirely suppressed in M. 

 Ohioticus, in both jaws. 



There is nothing, therefore, in the mode of succession of the 

 1 Ibid. PI. 144, fig. 7, jo. l. 



