ELEPHANT AND MASTODOX. 77 



extent of tooth surface, and a gradual diminution in the 

 thickness of the layer of enamel. Plate V. represents another 

 succession of links which, in like manner, conduct us from 

 the African elephant on to the extremity of the series in 

 E, primigenius. 



Fig. 1 of PI. V. (or fig. 3 a of PL I., F.A.S.) shows a section 

 of the penultimate upper molar of an undescribed Indian 

 fossil species, named E. Hysudricus in this work. The tooth 

 is in the middle state of wear, eleven of the thirteen plates of 

 which it is composed having been in use, and the two anterior 

 ridges being worn out. The same vertical disposition of 

 ivory, enamel, and cement is presented as in the African 

 elej)hant, but the plates are thinner and a greater number of 

 them is included in the same length, nine or ten plates in 

 the latter being developed in the space occupied by thirteen 

 or fourteen plates in the equivalent teeth of E. Hysudricus. 

 The plates are also more vertical, the interspaces occupied by 

 the cement are wider in general than the ivory plates which 

 represent very attenuated wedges. The layer of enamel is 

 proportionally thicker than in the African elephant, approach- 

 ing, in this respect, the teeth of E. planifrons, PI. IV. fig. 2. 

 The vertical height of the tooth is comparatively less in this 

 specimen than in the African species, the difference being 

 compensated by a greater development of the basal mass of 

 ivory. This specimen measures 7*7 inches in length. 



A portion of the last molar of the lower jaw of this 

 species is shown in vertical section in fig. 3 b (PL I., F.A.S. ), 

 comprising about fifteen plates. The entire tooth, which is 

 seen in figures 12 and 12 a of PL YII., F.A.S. , in situ in 

 the jaw, is more elongated, and includes a greater number 

 of divisions than is usual in the last inferior grinder of 

 E. Hysudricus. The same general character, in the disj)Osi- 

 tion and relative proportion of the ivory, enamel, and 

 cement, is exhibited as in the upper molar, PL V. fig. 1, 

 bearing in mind that the latter is a younger and conse- 

 quently smaller tooth. The laj^er of enamel, however, is 

 thinner than in the upper molar, owing to the unusually 

 large number of developed plates. The ivory segments 

 are curved backwards near their base, and the apices 

 of the posterior plates lean towards the front of the tooth, 

 a disposition which is still more strongly exhibited 

 in the lower teeth of the existing Indian elephant. The 

 grantilated dark shade, loelow the undiilated outline of the 

 ivory, indicates a core of sandstone, which occupies the j^lace 

 of the unossified part of the pulp nucleus and of the unde- 

 veloped fangs. Both specimens, oa and oh, PL L, F.A.S., 

 are implanted in portions of the jaws. 



