BRITISH AND EUROPEAN FOSSIL MASTODONS. 



discovery of the Mastodon Elephanto'ides of Clift, in which 

 Cuvier's characters of both genera are blended, and of 

 European and American forms with tusks in the lower jaw 

 (Mastodon longirostris and Mastodon Ohioticus), led to the 

 necessity of remodelling the technical diagnostic characters 

 of the genera. This was first attempted, so far as I am 

 aware, by Bronn of Heidelberg, in his ' Lethsea Geognostica,' 

 as far back as 1838. In his elaborate definition of the two 

 genera, he states (omitting other characters) that Mastodon is 

 characterized by lower incisors, and by molars which are 

 replaced from back to front, excepting, however, the most 

 anterior of these teeth, i.e. one or more milk molars ; while 

 in Elephant there are no inferior incisors, and all the molars 

 are replaced in a horizontal direction. 1 In his remarks upon 

 the species, he mentions that ' Tetracaxdodon (i.e. Mastodon 

 longirostris), according to Kanp, has premolars in the upper 

 jaw, which are very similar to the back molars of Hippopota- 

 mus and are very caducous,' 2 and in regard to inferior tusks, 

 that ' Mastodon giganteus, M. angustidens, and M. longirostris 

 do unquestionably possess such inferior tusks ; the other 

 species of Mastodon occur more rarely, and we can therefore 

 only by analogy infer their having possessed them also.' 3 

 The same characters, i.e. of premolars and inferior incisors, 

 were several years afterwards advanced by Prof. Owen (who 

 must obviously have overlooked the previous remarks of 

 Bronn) in his 'British Fossil Mammalia' 4 as being dis- 

 tinctive of Mastodon from Elephant in a well-marked and 

 unequivocal manner. But they are assuredly neither absolute 

 nor constant, whether regarded in a positive or negative view, 

 as generic distinctions. For on the one hand, premolars have 

 not yet been met with in M. (Trilophodon) Ohioticus, in place 

 in the jaws, although made a subject of special research by 

 Dr. Warren, 5 Dr. Jackson, and myself, upon a large quantity 

 of materials, up to a very late date ; nor have they been yet 

 met with in certain species of the Tetralophodon group ; 

 while, so far from being restricted to species of Mastodon, 

 they have been detected by us in a typical fossil Elephant 

 from India, E. (Loxodon) planifrons, both in the upper and 

 lower jaws, in as great a number as in any known Mastodon. 6 

 And as regards inferior tusks, although these have been ob- 

 served in three species of the Trilophodon group, and in two 

 of Tetralophodon, there are other species in which, among 

 abundant materials, they have not been noticed up to the 



1 Bronn, 'Lethsea Geognostica,' Band 4 ' Brit. Foss. Mam.,' p. 274. 



ii. pp. 1233 and 1239 (1st ed.). 5 Warren, On Mastodon giganteus, 



2 Id. loc. cit. p. 1218. p. 80. 



3 Id. loc. cit. p. 1233. 6 See vol. i. p. 433.— [Ed.] 



