132 DISTINCTION INTO SPECIES. 



Mastodon so that one, or it may be two, of tlie anterior ridges are effaced. The other 



Sivalensis. 



two present largely worn, and rather irregular terminations. Those of the 

 corresponding tooth on the opposite side have a trifoliated shape. The 

 enamel which surrounds the worn surfaces is a little irregular. 



On the whole, these teeth present the characters of the narrow rather 

 than the broad-toothed group, and are such as to entitle them fully to the 

 distinction of a separate species. Dr. Falconer, however, places the Siva- 

 lensis in a section with the Mastodon Latidens and Mastodon Arvernensis, 

 on the ground that they possess "the same numerical division of the crown- 

 ridges in the last deciduous molar, and in the first and second true molars 

 in both jaws." 



MASTODON LATIDENS. 



Mastodon This name has been assigned by Mr. Clift to a species whose remains 



Latidens. 



are found on the banks of the Iriwaddy. The teeth, for the most part 

 impregnated with the carbonate of iron, are broader than those of other 

 species. The last molar sometimes has as many as ten ridges and a talon : 

 a cast of one of these teeth in my possession, from a Paris specimen, has 

 six ridges of a serrated rather than tuberculated form, and a posterior 

 talon. This tooth, and that called Mastodon Elephantoides, form, as was 

 first noticed by Mr. Clift, two links connecting the Mastodon with the 

 Elephant. 



MASTODON TETRACAULODON. 



Mastodon The existence of a tusk in the lower jaw has given origin to the 



Tetracau- , , 



lodon. distinction into another species ; a distinction first proposed by Dr. God- 

 man, an excellent naturalist and anatomist, whose early loss the science of 



