CHARACTERS OF LOXODONS. £9 



Stegodons, and ' coronis lamellosa ' to those of Loxodon and 

 Euelephas. 1 It forms the basis of the arrangement of the 

 species of the Proboscidea, by De Blainville, into two gronps, 

 i.e. ' Elephants mastodontes ' and ' Elephants lamellidontes,' 

 the whole comprised in a single genus, Elephas. 



2. African Elephant. — De Blainville has attempted to de- 

 scribe and figure in detail the dental succession, from the 

 first milk molar of the young calf to the last true molar of the 

 adult state, in E. (Loxod.) Africanus. Of some of the ' inter- 

 mediate molars,' he was not in possession of perfect specimens ; 

 in these cases, his determination of the ridge-formula can 

 only be regarded as approximative. Another point, which 

 materially affects the numerical estimate of the ridges as- 

 signed by him to the different teeth is, that in every case he 

 counts the accessory ridgelets, or 'talons,' as ridges. His 

 results may be expressed thus for the number of ridges in the 

 different teeth : — 



Milk molars. True molars. 



4 + 7 + 6 7 + (9-10)+ 10 



4 + 7+ ?. ? + (8-9) +(10-12). 



This determination is open to the objections that the third 

 milk molar has a smaller number of plates assigned to it than 

 the penultimate, which is very much smaller in size, and that 

 the penultimate upper true molar is described by De Blain- 

 ville as possessing the same number of ridges as the last. 

 This occurs in no species of Mastodon or Elephant. De 

 Blainville has figured an instructive specimen, which proves 

 that the theoretical first or pre-antepenultimate milk molar 

 is occasionally developed in the lower jaw of the African 

 Elephant. 



Professor Owen has briefly described the ridge-characters 

 of the teeth of this species in the ' Odontography,' and 

 assigns the following numbers to the ridges in the six suc- 

 cessive molars, -i.e. 4 + 7+7: 7+ (8—9) + (10— 12), the last of 

 the ciphers being attributed to the sixth (or last true) molar 

 of the lower jaw. In this estimate, the ' talon ' is apparently 

 reckoned in some of the cases as one of the principal ridges. 

 I have examined the specimens upon which De Blainville's 

 descriptions were founded, and various molars of all ages in 

 different collections contained in museums in this country or 



1 These terms are adopted from the 

 logical and accurate Illiger. The ex- 

 pressions 'Bildung'or ' Entwickelung,' 

 ' Pyramidal,' ' Prismatisch,' applied by 

 Von Meyer and Bronn to characterize 

 the difference in structure betweon the 



teeth of Mastodon and Elephant appear 

 to convey the same meaning respectively 

 as the 'dens complicatus' and 'dens 

 lamellosus' of Illiger (vide Illiger's 

 ' Prodrom.' p. 22, and Bronn's Lethsea 

 Goognost. Band ii. pp. 753 and 797). 



