MASTODON ARVERNENSIS. 



39 



osteological characters, 1 which leave little room for doubt 

 that they were both Proboscidean genera, Dinotherium having 

 close affinities to the Tapirs, as Cuvier sagaciously inferred 

 in his earliest memoir on ' Les Tapirs Gigantesques.' 2 



Of the antepenultimate and penultimate milk molars no 

 specimens from the Crag have been as yet figured or described ; 

 but the characters presented by these teeth in M. (Tetraloph.) 

 Arvemensis are well known, both in the upper and lower jaws, 

 through the specimens discovered by Croizet and Jobert, 

 Bravard, and others in Auvergne or the Velay. _ The ante- 

 penultimate presents two ridges, and the penultimate three 

 ridges, with the usual talon complications. They are readily 

 distinguishable — the upper from the lower — when met with 

 detached, from the circumstance that the milk molars of the 

 lower jaw are narrower and more compressed, the antepenul- 

 timate being reduced to a single cusp. Figures of these teeth 

 are given by Croizet and Jobert in the work already referred 

 to. 3 



The ridge-formula in the molar teeth of" the Crag Mastodon, 

 including milk and true molars, but exclusive of premolars, 

 as inferred from the various data detailed in the previous 

 pages, is — 



Milk molars. 



2 + 3 + 4 

 2 + 3 + 4 



True molars. 



4 + 4 + 5 



4 + 4 + 5 



The assigned numbers have not been verified in every instance 

 upon Crag remains ; but they are all founded on an examina- 

 tion of specimens, of which some were of foreign origin, when 



materials were not available from the Crag. 4 



1 In M. Ziegler-Ernst's Winter-thru- 

 specimen of the young lower jaw above 

 referred to, five molar teeth are present, 

 viz. the penultimate and last premolars 

 — the former extruded, the latter em- 

 bedded; the last milk molar far advanced 

 in wear, and immediately over the last 

 premolar; and the antepenultimate and 

 penultimate true molars both in germ, 

 but the former partially emerged and 

 in incipient use. 



2 Annalesdu Museum, torn, iii.p. 132. 



3 Oss. Foss. du Puy-de-D6me, PI. i. 

 figs. 1-3 and PL ii. fig. 7. 



4 In the description of the various 

 teeth throughout this memoir, the terms 

 antepenultimate, penultimate, and last 

 have been used, instead of the numeral 

 expressions of first, second, and third, 

 when designating the, position either of 

 the milk or of the permanent molars. 

 This would seem indispensable when 



symbols are not employed, to avoid con- 

 fusion in the designation of the milk 

 molars, since the typical first or the most 

 anterior of the milk molar series, which 

 is present in many other pachydermatous 

 genera, is constantly suppressed in the 

 Mastodons, and generally also in the 

 Elephants. When, therefore, the terms 

 first, second, and third milk molars are 

 applied to Mastodon, they are not the 

 equivalents of the same numerals applied 

 to Bhinoceros or Hippopotamus, in which 

 all the four milk molars are developed ; 

 whereas the terms antepenultimate, pe- 

 nultimate, and last in every case repre- 

 sent homologous teeth in the milk molars 

 of all the ungulate genera. This is the 

 more necessary, as the theoretical first 

 or pre-antcpenultimate milk molar is 

 occasionally met with in the African 

 Elephant. DeBlainville (Osteographie : 

 Des Elephants, tab. ix. p. 81) has given 



