DESCKIPTION OF PLATES. 423 



the height of which is many times greater than the width of their base. 

 The interspaces are deep and filled up with copious cement. The enamel 

 and common basal mass of ivory are much less than in either E. insignis 

 or E. planifrons, the latter being only sufficient to establish a common 

 connection between the bases of the segments, and a foundation for the 

 offset of the fangs, which are numerous. (Reproduced in PI. IV. fig. 3.) 



Length, 87 in. 



Fig. 4 h. — Elephas Africanus. Vertical section of penultimate molar 

 of lower jaw, belonging to Mr. C. Stokes. It is composed of nine 

 cuneiform plates. This tooth had been a long time in use, all the 

 plates, except the last being affected by wear. The anterior part of the 

 crown has been ground down to nearly one-third of its original height, 

 so that the enamel divisions between the two anterior ivory plates have 

 disappeared, and the latter are confluent into a common mass. The 

 section exhibits the same kind of Avedge- shaped ivory plates, a similar 

 amount of cement in the interspaces, and an analogous thickness of 

 enamel as in E. planifrons, fig. 5 b. 



Length, 7'2 in. 



Fig. 5 a, — Elephas planifrons, fi-om the Sewalik hills. Vertical section 

 of penultimate upper molar, with nine ridges, the three anterior of 

 which alone have been in use, the two first being worn down to a 

 single disc of ivory. The ridges are seen to be much more elongated 

 vertically than in E. insignis (fig. 6 a), but to be considerably less so 

 than in the African Elephant. From the latter it also differs in the 

 enormous quantity of cement, filling up the valleys and enveloping the 

 ridges, and in the much greater thickness of the folded plates of enamel. 

 The enamel is reflected over the ridges of ivory, and down into the 

 hollows zig-zag wise, exactly as in E. insignis. — B.M. (Eeproduced in 

 Plate IV. fig. 2.) 



Length, 8' 7 in. 



Fig. 5 h. — Elephas planifrons. Vertical section of portion of last 

 molar of lower jaw, with nine ridges, and presenting the same general 

 characters as fig. 5 a. The lower tooth, however, had been longer in use, 

 and all the ridges are more or less worn, except the two last. — B.M. 



Fig. 6 a. — Elephas insignis, from the Sewalik hills. Vertical section 

 of last upper molar. The four anterior ridges are affected by wear ; 

 the six posterior ridges are entire, the fangs are fully developed, and 

 their mode of implantation in the jaw is distinctly shown. The white 

 mass in the centre represents the body of ivory, which is projected 

 ' upwards in ten angular lobes, terminating in a sharp edge. The height 

 of these lobes does not much exceed the width of their base, and closely 

 applied over them is a thick layer of enamel reflected up and down in 

 a continuous zig-zag plate. The interspaces of the five posterior ridges 

 of enamel are completely filled up by a mass of cement much exceeding 

 the enamel in thickness {vide Plate VI. fig. 7). This is the best illustra- 

 tion of the intermediate type of a proboscidean molar tooth, from which 

 those of the other species diverge in opposite directions. It belongs to 

 the Mastodon Elephanto'ides of Clift. The dark granulated shade, 

 below the portion of the ivory nucleus sustaining the five posterior 

 ridges indicates the hollow of their common fang, which in the fossil is 

 occupied by a core of sandstone — B.M. (Reproduced in PI. IV. fig. 1.) 



Length of tooth, 10-3 in. 



