80 FAUNA ANTIQUA SIVALENSIS. 



order of structural deyelopment iii the teeth, does not cori'e- 

 spond with the order of succession of the species in time. 

 The extmct mammoth exhibits the greatest anaount of com- 

 plexity, constituting the terminal link of the chain ; and next 

 follows the existing Indian elephant, interposed between two 

 fossil species. In like manner, the existing Aft-ican elephant 

 is placed between two extinct species, E. Hysudricus and 

 E. planifrons. The figured sections include only the prin- 

 cipal forms requisite to establish the passage. Another 

 extinct Indian species, E. Namadicus (to be described in the 

 sequel), which is closely alHed to the existing Indian form, 

 comes between it and E. Hysudricus, together with a European 

 fossil species, which we believe to be distinct from the mam- 

 moth ; and the gap between the existing African elephant 

 and E. planifrons is filled uj) by another well-marked 

 European fossil species, E.priscus (?), PL XIY. fig. 7, F.A.S., 

 which is closely allied to the former. This species will also 

 be noticed in a subsequent page. 



We shall now revert to E. insignis, and endeavour to trace 

 the forms which diverge from it in an opposite direction 

 through the mastodons, the tendency in this series being to- 

 wards a greater simplicity in the construction of the grinders, 

 and a reduction in the number of coronal segments. 



Fig. 1, PI. YI. (or fig. 7 a, PL III., F.A.S.), represents a sec- 

 tion of the last ujiper molar of an undescribed Indian fossil 

 species, named E. Ganesa, in this work. The crown consists 

 of ten pi'incij)al ridges, with a subordinate 'talon' ridge in 

 front and behind. The anterior seven ridges have their 

 summits worn, the two in front being ground down to the 

 common base of ivory, the tooth having been a considerable 

 time in use. A small portion is broken off at the anterior 

 end. The disposition and relative proportions of the ivory, 

 enamel, and cement, bear the closest resemblance to those of 

 the corresponding tooth of E. insiynis (Plate IV. fig. 1), and 

 the number of ridges agrees. The section presents the same 

 chevron-formed character in the ridges, but the interspaces 

 are narrower, the cement is in less quantity, and the layer of 

 enamel is thicker. The common grinding sui'face of the 

 crown is also less convex. But these differences are so 

 inconsiderable, when taken into account with the range of 

 variation through which the molars run, that they are practi- 

 cally insufficient for the discrimination of the two species. 

 To guard against error, the sections have been taken in both 

 instances from specimens consisting of the palate with a 

 double line of teeth ; and, notwithstanding that the molars 

 agree so closely, the crania are remarkably different in the 

 two forms ; that oiE. insignis, PL XV., F.A.S. , being singidarly 



