1857.] FALCONER MASTODON. 337 



rinferieure comme cela a lieu dans le Dinotherium ; la premiere n'est 

 jamais remplacee." In a beautiful specimen of the lower jaw of a 

 young il/. {Trilophodoii) angustidens, belonging to M. Ziegler-Ernst 

 of Winterthur, I found both the penultimate and last premolars 

 present, the former protruded, the latter in germ. When a single 

 premolar is developed, it is the successor to the last milk-molar, and 

 not to the penultimate, as stated by Prof. Owen in the passages above 

 referred to *. I have seen detached specimens of this last premolar, 

 both of the upper and lower jaws of il/. (Tetralophodon) longirostris 

 of Eppelsheim, in the Museum at Darmstadt. The order of succes- 

 sion here indicated is alone consistent with what occurs in other 

 Pachyderms, where, when suppression in either of the milk- or pre- 

 molar series takes place, it is constantly the anterior or feebly deve- 

 loped and rudimentary teeth that are suppressed. In them we never 

 find the last premolar suppressed while the penultimate is developed, 

 but the reverse. The penultimate premolar replaces only the cor- 

 responding milk-molar : the ante-penultimate milk-tooth is never 

 replaced in Mastodon or Elephas, so far as observation has yet shown. 

 The molar dentition of the permanent or second set (i. e. the pre- 

 molars and true molars) in M. {Triloph?) angustidens and Dino- 

 therium is numerically identical, consisting of two premolars and 

 three true molars ; each of these having also two well-developed man- 

 dibular tusks : and the close affinity thus indicated by the number of 

 teeth is further borne out by the correspondence of a ternary-ridged 

 formula in two of their "intermediate molars," and by other osteo- 

 logical characters f , 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 %• 



Of the ante-penultimate and penultimate milk-molars no speci- 



* In his subsequent memoir on the molar teeth of Phacochoerus, &c. (Phil. 

 Trans. 1850, p. 496), Professor Owen takes a different view of the premolar teeth 

 in Mastodon from that set forth in the ' British Fossil jNlammaha ' and the ' Odon- 

 tography.' It is expressed thus : — " The existing species of the gigantic Probos- 

 cidian family, viz. the Asiatic and African Elephants, are totally devoid of incisors 

 on the lower jaw, and all their grinding teeth succeed each other horizontally ; so 

 that it is only by a more than proportional increase of size that the ante-penulti- 

 mate grinder is recognizable as the first of the true molar series, and the ante- 

 cedent smaller grinders, as the homologues of the milk-molars of other Diphyo- 

 donts, which milk-molars have no successors in the Elephants. In certain Mas- 

 todons, however, which are the earliest known forms of the Proboscidian family, 

 the last milk-molar was displaced by a vertical successor or premolar." The 

 tooth, which, in his earliest descriptions, was considered as the successor of the 

 ante-penultimate and penultimate (first and second) milk-molars, is here regarded 

 as the successor of the last milk-molar. But the presence of both the penulti- 

 mate and last premolars in Mastodon angustidens is not recognized. 



t In M. Ziegler-Ernst's Winterthur 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 imbedded ; the last milk-molar far advanced in 

 wear, and immediately over the last premolar ; and the ante-penultimate and pen- 

 ultimate true molars both in germ, but the former partially emerged and in in- 

 cipient use. 



X Annales du Museum, torn. iii. p. 132. 



