264 PEOCEEDIlirGS OF THE GEOLOGICAl SOCIETY. 



prises three fossil species, of which one is Indian, E. (Lo:cod.) 

 planifrons, from the Sewalik Hills, and two European, namely, 

 E. (^Lowod.) priscus and E. (Loxod.) meridionalis. The essential 

 characters by which the molar teeth of the Loxodons differ from 

 those of the Stegodons is that the ridges or coUiculi, while 

 closely corresponding in regard of number, are considerably more 

 elevated and compressed. This is best seen when they are sawn up 

 longitudinally and vertically : the section in the Stegodons exhibits 

 a series of chevron-shaped ridges, of which the height does not 

 much exceed the base, with thick enamel, and assimilating closely 

 in form to the true Mastodons*; while in the Loxodons f it pre- 

 sents a succession of elongated wedge-shaped processes, with 

 thinner enamel, constituting an intermediate stage between the 

 former and the nearly parallel thin-plated ridges of the next group, 

 Euelephas. In the technical definition of the subgenera appended 

 to the preceding part, this distinction is attempted to be expressed 

 by the terms " coronis complicata" applied to the teeth of the 

 Stegodons, and " coronis lamellosa" to those of Loxodon and Euele- 

 phasX- It forms the basis of the arrangement of the species of the 

 Proboscidea, by De Blainville, into two groups, i. e. " Elephants 

 mastodontes " and " Elephants lamellidontes," the whole comprised 

 in a single genus, Eleplias. 



2. African Elephant. — De Blainville has attempted to describe 

 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.) Africamis. Of some of the " intermediate molars," he 

 was not in possession of perfect specimens ; in these cases, his 

 determination of the ridge-formula can only be regarded as approxi- 

 mative. Another point, which materially affects the numerical 

 estimate of the ridges assigned 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 

 m the different teeth : — 



Milk-molars. True molars. 



44-7 + 6 7+(9-10)-h 10 



4 + 7-^?. ?-t-(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 penul- 

 timate, which is very much smaller in size, and that the penulti- 

 mate upper true molar is described by De Blainville as possessing 

 the same number of ridges as the last. This occurs in no species of 



* ' Fauna Antiqua Sivaleusis,' Illustrations, pi. 2. figs. 6 a & 6 5. 



t Ibid. pi. 2. figs. 4 a & 4 5. 



X These terms are adopted fi'om the logical and accurate Illiger. The 

 expressions " Bildung" or " Entwickelung," " Pyramidal," " Pi-ismatisch," 

 applied by Von Meyer and Bronn to characterize the difference in structure 

 between the teeth of Mastodon and Elephant; appear to convey the same 

 meaning respectively as the " dens complicatus " and " dens lamellosus " of 

 nUger {vide lUiger's 'Prodrom.' p. 22, and Bronn's Lethsea Geognost. Band 

 ii. pp. 753 and 797). 



