185/.] FALCONER — MASTODON. 317 



Inferior incisors have been discovered in M. (Triloph.) angustidens , 

 M. {Triloph.) Ohioticus^ and M. (Triloph.) tapiroides; and also 

 in M. (Tetraloph.) Andium and M. (Tetraloph.) longirostris, in 

 the first of which they occasionally attain a very large size. They 

 do not appear to occur ever in M. (Tetraloph.) Sivalensis, nor in 

 M. (Tetraloph.) Arvernensis. Their presence or absence in the 

 tvro other species of Tetralophodon has not yet been satisfactorily 

 determined. The ridge-formula, as being respectively ternary in 

 Trilophodon and quaternary in Tetralophodon^ is very constant, the 

 only doubtful case being presented by the form or forms named 

 Mastodon Andium by the French palaeontologists. Cement, al- 

 though quantitatively inconspicuous in most of the species of both 

 subgenera, is present in considerable abundance in the valleys of the 

 crowns of M. (Tetralophodon) Perimensis and in M. {Triloph.) 

 Humboldtii. In the former it fills up the bottom of the interstices 

 between the mammillae. The transverse or alternate direction of the 

 mammillae of the ridges, and the open or interrupted nature of the 

 valleys connected therewith, are not equally defined in all the species, 

 intermediate stages being met with. But the ridges are invariably 

 transverse and the valleys open in M. {Triloph.) Borsoni, Ohioticus^ 

 and tapiroidesy and in ilj. (Tetraloph.) latidens; while the mammillae 

 are constantly more or less alternate, and the valleys interrupted 

 among the Trilophodons in M. (Triloph.) angustidens, Hiunholdtiiy 

 and Pandionis ; and among the Tetralophodons in M. (Tetraloph.) 

 Sivalensis and Arvernensis. The most complex crowns are pre- 

 sented in the Trilophodons by M. (Triloph.) Pandionis (an Indian 

 fossil species recently discovered and as yet undescribed), and M. 

 (Triloph.) Humboldtii ; and among the Tetralophodons by M. (Te- 

 traloph.) Sivalensis and Arvernensis. The upper adult molars in 

 several of the species (e. g. M. (Triloph.) angustidens and M. {Te- 

 traloph.) Andium) were invested with a longitudinal belt of enamel, 

 disposed more or less spirally, and reaching the apex. The lower 

 incisors, according to Lartet, are constantly devoid of any such belt. 

 In M. (Ti'iloph.) angustidens inferior incisors would appear to have 

 been common to males and females, and not to have been a mark 

 merely of sexual difference. Mastodon Sivalensis, although with 

 five-ridged "intermediate molars," is provisionally included under 

 Tetralophodon. 



Genus Elephas (Linn.). 



Form. Dent, decid. — Primor. ^ ; Lan. ^ ; Mol. -|= 7. 

 Form. Dent, persist. — Primer.— ; Lan.—; Pramol. - vel ^; 

 Mol. 1= 11-7. 



Primores eburnei plerumque exserti, sursum et antrorsum adscen- 

 dentes. Molar es aut complicati aut lamellosi, tritores ; coro- 

 nidis longitudinaliter integrse collicuU convex! e tuberculis mam- 

 millaribus, aut laminis cuneiformibus vel compressis digitatis 

 transversis, constantes : adamant e illis crasso, his attenuato, 

 ccemento in valliculis copioso. Prcemolares rarissime utrinque 

 2 (saepius nulli), caeteris forma simpliciores, minores. Molares 



