FALCONEE MASTODON AND ELEPHANT. 263 



outer division, and generally more or less effaced by the pressure of 

 the next posterior molar during its progress forwards. In a fine 

 specimen of a penultimate upper molar of Mastodon Sivcdensis, 

 which is now before me, the fifth ridge, although well developed 

 and attaining the height of the fourth, bears no trace of a "talon" 

 appended to it; while an antepenultimate lower, which I have also 

 before me, shows distinctly five ridges, the last differing in no 

 respect of complexity or development from the others, except in 

 being a little smaller, and it bears a distinct crenidated adpresscd 

 "talon" appendage, having the ajipearanee of a terminal " bour- 

 relet." 



In the preceding part, when discussing the conditions of the 

 " ridgc-formula " in TrilopJwdon and Tetrcdopliodon, it was stated 

 that while the penultimate milk-molar always presents one ridge 

 less than the " intermediate molars," the last true molar presents 

 one ridge more. Conformably, the last true molar in M. Sivcdensis 

 presents six ridges, besides the hind " talon," thus maintaining 

 throughout, so far as the dentition is known, the numerical cha- 

 racters to be inferred from the ridge-formula, as ascertained in 

 Trilophodon and Tetrcdophodon. I consider it sufficient, on the pre- 

 sent occasion, to call attention to this as a point of some interest and 

 importance in the systematic and palseontological relations of the Pro- 

 boscidean family, in reference to the indications they present of an 

 order of successive serial development, without entering in detail 

 upon the evidence in support of the view here taken. That the 

 species is a distinct form is abundantly borne out by the marked 

 characters of the skull*, independently of the strong dental dis- 

 tinctions. The ridge -formula for the true molars in Mastodon Siva- 



5-1-5-1- 6 



lensis, is inferred to be '- — -^ — - ; and when the dentition is 



+ 5-1-6-7 



fully made out, it is anticipated that the complete ridge-formula 

 will be nearly thus : — ■ 



Milk-molars. True molars, 



2 + 4-H5 5-|-5-f 6 



2 + 4 + 5 . 5 + 5 + 6-7. 



V. Chaeactees oe the Loxodons. 



1. General Bonarlcs. — The existing typn of tlis group is the Afri- 

 can Elephant, which Fred. Cuvier,in 1835, proposed to erect into a 

 distinct genus under the name of Loxodonta, having reference to 

 the rhomb-shaped disks of wear of the molar teeth. He held the 

 opinion that, in its general form, in the structure of its grinders, 

 in the form of the head, and in that of some of the external 

 parts of the organs of sense, the African differs as much from the 

 Indian Elephant as the Dog from the Hysena, the Paea from the 

 Agouti, the Lagomys from the Hare, and the Hog from the Plieo- 

 chceref. Besides the African Elephant, the group Loxodon com- 



* Vide 'Fauna Antiqua Sivalensis,' pi. 32. 



t F. Cuvier,'Histoire Naturelle des Mammif.' torn, iii., " Elephant d'Afrique." 



