1857.] FALCONER MASTODON. 321 



formula which is identical or nearly so with that of Stegodon insignis ; 

 but the separation of the group is indicated by the great increase 

 of vertical height in the colliculi, and by the layers of enamel 

 assuming the character of plates, instead of the mastoid eminences 

 of Stegodon. E. (Lox.) meridionalis has a higher number of plates 

 in the " intermediate molars" than those two species, and con- 

 stitutes a frontier form, leading towards the next group, Euelephas. 

 But the ridge-formula in this form would appear to be hypisomerous, 

 and the aggregate characters indicate its position among the Loxodons. 

 The majority of the species in the group Euelephas are well marked 

 by the progressive increments and high numerical expression of the 

 crown-ridges of the intermediate molars, by the great vertical height 

 of the colliculi, and the attenuated plates of enamel. One species 

 among them, E. (Eueleph.) Hysudricus^ constitutes a frontier form 

 leading towards E. {Lox.) meridionalis. More ample details re- 

 specting the Elephants will be given in the Second Part of this 

 memoir, when treating of the European fossil species. 



To revert specially to the Mastodons, Trilophodon and Tetralo- 

 phodon (including under the latter the exceptional five-ridged Mas- 

 todon Sivalensis) y as regards the number of forms at present known, 

 are of nearly equal value, the former in our view comprising 7, and the 

 latter 6, well-marked species ; and they are each divisible into two 

 parallel subordinate groups, the exact appreciation of the characters 

 of which is of much service in the determination of the European 

 fossil species. In the one series, the ridges are broad, transverse, 

 more or less compressed into an edge, with the valleys open through- 

 out and uninterrupted by subordinate tubercles : these are well 

 represented in Trilophodon by M. (Triloph.) Ohioticus, and in 

 Tetralophodon by M. {Tetral.) latidens. In the other series, the 

 ridges are composed of blunt conical points, which are fewer in 

 number, more elevated, and flanked in front and behind by one or 

 more subordinate outlying tubercles, which disturb the transverse 

 direction of the ridges, and block up the valleys, interrupting their 

 continuity across. This series is represented in Trilophodon by the 

 Miocene European species M. (Triloph.) angustidens, and in Tetra- 

 lophodon by the Pliocene M. (Tetraloph.^ Arvernensis of the Crag 

 (See Plates XI. & XII.). The species with transverse, compressed 

 ridges, in both subgenera, may be compared with DinotheriuMy as 

 regards their molar crowns ; and the other series with Hippopo- 

 tamus. 



The European fossil species of Mastodon at present known are the 

 following*, — all of which are of Miocene age, with the exception 



* M. Aymard has added largely to the nomenclature of the Proboscidea by 

 creating a new genus, and new species for the remains found in the Velay and 

 Auvergne, viz. : Anancus macroplus, as a generic form distinct from Mastodon ; 

 and M. Vellavus and M. Vialettii, regarded by Pomel as synonyms of M. Borsoni; 

 also a fossil Elephant, E. giganteus, Aym. But the specific distinction of these 

 nominal species is exceedingly doubtful {vide Bulletin de la Societe Geologique ; 

 andCongres Scientifique de France, 1855, p. 276). The species referred to in a 

 preceding page as having been made out l)y M. Lartet has not yet been published. 



