ELEPHANT AND MASTODON. 31 



instead of being invariably wanting in the Elephants, are deve- 

 loped in greater number in one typical fossil species, than they are 

 known to be in any ascertained species of Mastodon ; while, on 

 the other hand, they do not appear to be constant in every species 

 of the latter group ; and, although the inferior tusks have been 

 observed in three species of Mastodon, there are other forms in 

 which they have not yet been detected, even in specimens of the 

 young animal. 



With respect to the European species, Professor Owen con- 

 siders, like M. de Blainville, that M. angustidens and M. longi- 

 rostris belong to a single form ; and he refers the whole of the 

 elephantine remains which occur so plentifully in England, 

 whether in the fluvio-marine crag, or in the superficial drift and 

 gravel, also to a single species, E. primigenius. He describes 

 the dentition of the Indian species, discovered by Clift, under the 

 designation of Transitional Mastodons. 



We shall now proceed to the special consideration of the teeth, 

 as the organs which have the greatest share of influence in deter- 

 mining the modifications in the construction of the cranium, and in 

 the development of the general form, presented by the different 

 species in the Proboscidea. 



§ II. — On the Structure and Form of the Molar Teeth. 



Plates 1, 2, and 3 are intended to represent, by careful copies 

 of nature, the modifications in structure and form exhibited by 

 the molar teeth of the Proboscidea ; they show, in vertical sections, 

 a series of gradations, commencing with Dinotherium and Mas- 

 todon Ohioticus at one extremity, and running through the other 

 species to Elephas primigenius, in which the greatest deviation 

 from the ordinary form of a grinding tooth is met with. 



Each molar in the Proboscidea? as is the case with all other 

 animals, is developed within a closed membranous sac, called the 



1 The substance of the four following paragraphs is drawn from the admirable descrip- 

 tions given by Cuvier in the Ossemens Fossiles, torn. i. p. 32, and by Owen in his valu- 

 able systematic work on the teeth. Odontography, p. 649. 



