330 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [April 8, 



Mastodon so far as the alternate disposition of the crown-mammillse 

 is concerned, but differing in the ridge-formula. Figs. 8 and 9 re- 

 present two specimens of the same tooth of M. {Tetralo^^hodon) Ar- 

 vernensis, the one being Mr. Vv^illiam Smith's Whitlingham fossil, 

 and the other, fig. 9, Captain Alexander's specimen, dredged np be- 

 tween Southwold and Easton, of which there is a cast in the Geolo- 

 gical Society's Museum. Figs. 12 and 13 represent two specimens, 

 of different races or sexes, of the same tooth of M. {Tetralophodon) 

 longirostris, from Eppelsheim. The Sewalik molar, fig. 6, exhibits 

 six ridges and a hind "talon"; the Crag and Eppelsheim molars 

 show only five ridges and the "talon." In the Eppelsheim teeth, 

 figs. 12 and 13, the crown is broad, the mammillae are thicker in 

 proportion to their height, the ridges are less elevated, and consist of 

 a greater number of coronal points (there being often as many as 

 six or seven to each ridge), the outer and inner lines of points con- 

 verge less towards the apex of the crown as they rise upwards, and 

 the valleys are either entirely open and transverse, or interrupted 

 only by an insignificant amount of warty tubercles. In the Crag 

 fossils, figs. 8 and 9, the crown is narrower in proportion, the raam- 

 millse form more attenuated cones, and are more elevated ; the 

 ridges consist of fewer coronal points, which, instead of running 

 across in a wide crest, appear, so to speak, as if they had been 

 squeezed together, and their transversality disturbed ; the outer and 

 inner lines of points, especially the latter, converge rapidly as they 

 ascend, rendering the apex of the crown much narrower than the 

 base ; the outer and inner divisions of the crown are more or less 

 alternate, and the vallicular niammillse that flank and alternate 

 with them are large conical points, which yield discs of wear 

 approaching in size to those of the princi})al points ; the valleys 

 are completely obstructed by these mammillse, and reduced to a 

 gorge on either side of them. Y^^hen the teeth are viewed in pro- 

 file, such as fig. 8, on the above-mentioned plate, compared with 

 fig. 13, the difference is very marked, the latter yielding a series 

 of salient and re-entering angles, corresponding with the prominent 

 points and valleys, which the former does not, the re-entering angles 

 being intercepted by a dark shade, which represents the accessory 

 mammiilse. If the eye is next directed to figs. G and 6«, the differ-' 

 ences are still more marked, M. {Tetralojyhodon) Sivalensis exhibit- 

 ing a greater amount of alternation of the crown-mammillae, and 

 more complexity of pattern, than is even seen in the English Crag 

 Mastodon. To summarize the distinctive characters of the two 

 European species, it may be stated, that M. (Tetr.) Arvernensis 

 (PL XII.), with M. (Tetr.) Sivalensis, resemble the Hippopotamoid 

 type, and M. {Tetr.) longirostris (PI. XL fig. 1), with the Indian 

 species M. (Tetr.) latidens, the Dinotherian type, in so far as the 

 form of the crowns of the molar teeth is concerned. 



Of the last true molar of the lower jaw no good entire specimen, 

 so far as I am aware, has yet been published as having been yielded 

 by the English Crag. But in the Museum of the Geological Society 

 there is a cast of a very fine specimen of this tooth from the left 



