46^ Geological Society .•— ■ " 



GEOLOGICAL SOCIETY. 



[Continued from p. 388.] 



■ April 8, 1857.— Colonel Portlock, R.E., President, in the Chair. 



The following communication was read : — 



" On the Species of Mastodon and Elephant occurring fossil in 

 Great Britain.— Part I. Mastodon." By H. Falconer. M.D., F.R.S., 

 F.G.S. 



The object of this communication is to ascertain what are the species 

 of the Proboscidea found fossil in Britain ; what the specific names 

 which ought to be applied to them ; and what the principal forma- 

 tions and localities where they are elsewhere met with in Europe, 

 The Mastodon of the Crag forms the subject of this first part of the 

 memoir : the second part will treat of the Elephant-remains found 

 in Britain. The author commenced by insisting on tlie importance 

 to geologjf that every mammal found in the fossil state should be 

 defined as regards, first, its specific distinctness ; and, secondly, 

 its range of existence geographically and in time, with as much 

 severe exactitude as the available materials and the state of our 

 knowledge will admit. He observed that with regard to the remains 

 of the proboscidean genera, Dinotherium, Mastodon, and Elephant, 

 some of which abound in the miocene and pliocene deposits of 

 Europe, Asia, and America, the opinions respecting the species and 

 their nomenclature, in all the standard palseontological works on 

 the subject, are extremely unsettled and often contradictory. 



Dr. Falconer then proceeded to explain his views of the natural 

 classification of the proboscidean Pachydermata, recent and fossil, 

 according to dental characters. In the Dinothere, with its tapiroid 

 molars, the last milk-molar and the antepenultimate (or first) true 

 molar are invariably characterized by a " ternary-ridged-crown- 

 formula," or in other words, their crowns are divided into three trans- 

 verse ridges. In the Mastodon not only the last milk-molar and 

 the first true molar, but also the second or penultimate true molar 

 (being three teeth in immediate contiguity), are invariably charac- 

 terized in both jaws by an isomerous division of the crown into either 

 three or four ridges ; or, in other words, are severally characterized 

 by either a " ternary-" or " quaternary-ridge- formula." These 

 three isomerous-ridged teeth are referred to as " the intermediate 

 molars." To the ternary-ridged species the author assigns the sub- 

 generic name of Trilophodon ; and Tetralophodon, to the quaternary- 

 ridged species. The molar in front, and that one behind these in- 

 termediate molars are also characteristically modified in these two 

 subgenera. In Trilophodon the penultimate or second milk-molar 

 is two-ridged, and the last true molar is four-ridged: in Tetralophodon, 

 the former is three-ridged, and the latter five-ridged. The author 

 considers it highly probable that a subgeneric group characterized 

 by a quinary-ridge-formula (Pentelophodon) has existed in nature, 

 but of which no remains have yet been discovered. 



The Elephants are distinguished from the Mastodons by the absence 

 of an isomerous-ridge-formula, as regards the three intermediate 



