340 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [April 8, 



spire, so as to be presented on the upper surface near the tip. 

 M. Lartet has never observed any indication of a belt of enamel 

 on the lower incisors. In the superb complete skeleton which was 

 disinterred by Laurillard at Seissan, the extruded portion of these 

 lower incisors measures 20^ inches, that of the upper tusks being 

 41 inches. The characters above indicated are constant, where- 

 ever the lower jaw of this species has been discovered, whether 

 in the Faluns of the Orleannais and Touraine, in the Lacustrine 

 deposits of Gascony and Languedoc, or in the Miocene Molasse 

 of Switzerland, where I found them confirmed by the examination 

 of two very fine specimens, young and old, found in the neighbour- 

 hood of Winterthur. They are well shown by the representa- 

 tions given inDe'Blainville's ' Osteographie : des Elephants,' pi. 14. 

 The molar teeth in all these specimens have constantly presented 

 the normal marks of the Trilophodon-6iV\^\on, namely three ridges 

 to the last milk-molar, and to the ante-penultimate and penultimate 

 true molars. 



In M. (Tetralophodon) longirostris the ascending ramus is con- 

 siderably more elevated than in M. {Triloph.) angustidens, approach- 

 ing more the character which is seen in the Elephants proper ; the 

 horizontal ramus is less compressed and more circular in section ; 

 instead of presenting the greatest height in a line with the com- 

 mencement of the alveolar border, or mentary foramen, it is con- 

 tracted there, in consequence of the lower margin rising upwards to 

 slope oif into the base of the symphysial beak*. This beak is very 

 massive and comparatively short, not exceeding the length of the 

 horizontal ramus, from the mentary foramen to the anterior margin 

 of the ascending ramus. Instead of being, as it were, a deflected 

 continuation of the inferior border of the jaw, as is seen in M. {Tri- 

 lophodon) angustidens, the beak in the Eppelsheim species is thrown 

 off in a plane nearly parallel with the inferior border, but separated 

 from it and raised above it by a step. It is deflected slightly down- 

 wards ; but, instead of forming a long slender apophysis as in the other 

 species, it shows a thick mass traversed by a broad gutter. The 

 greater extent of the beak is made up of the alveoli of two mandibu- 

 lar incisors, as in M. (Trilophodon) angustidens. These teeth have 

 not yet been found in situ, Kaup has figured three specimens f 

 which he conjecturally considers to be lower incisors. The greatest 

 diameter of the largest he states to be 2*75 inches. The molars of 

 these Eppelsheim jaws have constantly exhibited the Tetralophodon^ 

 character of four ridges to the crowns of the intermediate teeth ; the 

 ridges being transverse, with the valleys nearly uninterrupted. 



In the Pliocene M. {Tetraloph.^ Arvernensis, the lower jaw differs 

 widely from that of the other two species. The ascending ramus is 

 well elevated above the grinding-plane of the teeth, as in M. {Tetra- 

 loph.) longirostris. The horizontal ramus is very massive, without 

 compression, and yields a section which is nearly circular, as in that 



* Kaup, Oss. Foss. de Darrast. tab. 19. fig. 1. 



t Ossemens Fossiles de Darmstadt, tab. 3. figs. 1, 2, 3. 



