78 FAUNA AXTIQUA SIYALEXSIS. 



Tlie existing Asiatic elephant, E. Indicus, furuislies the 

 next modification represented in this plate. Fig. 2, PI. V. (or 

 fig. 2 a, PI. I., r.A.S.), shows a section of the penultimate 

 upper molar of this species. The gradual attenuation of the 

 plates, successively exhibited from E. insignis to E. Hysudricus, 

 is here carried to excess, eighteen of these divisions being com- 

 prised within the space occupied by about nine in the 

 equivalent tooth of the African species. They are produced 

 verticaUy in the same proj^ortion, the height of the middle 

 plate beuig about three-fourths of the entii-e length of the 

 tooth ; they, in fact, represent parallel perpendicular lamellae, 

 of nearly uniform thickness from the base to the apex, 

 interstratified with layers of cement of nearly the same 

 thickness. The layer of enamel is attenuated into a thin 

 transversely undulated brittle plate, the surface of which is 

 deeply wrinkled with striae, for the firm cohesion of the 

 cement. The general character of the section is a pectinated 

 arrangement of the lobes like the teeth of a comb,, which 

 conti'asts strongly with the chevi'on-formed ridges of E. 

 insignis, and the cimeiform plates of E.planifrons. The mass 

 of ivory at the base of the tooth is much thiimer than in the 

 corresponding molar of E. Hysudricus, bearing but a very 

 slender proj)ortion to the height of the tooth ; and numerous 

 small and distinct fangs are given off from its inferior edge. 

 This tooth had been some time in use, the anterior part of 

 the crown being worn off as far as the ninth plate. The plane 

 of the truncated portion is very oblique, being inclined 

 nearly at a right angle to the coronal surface of the unworn 

 portion. This specimen is 8*2 inches in length. 



Fig. 2 b, PI. I., r.A.S., rej)resents the section of a very fine 

 sj)ecimen of the last inferior molar of the existing Indian 

 elej)hant of Assam, from the collection at the India House. 

 It is an miusually large specimen, showing as many as 

 twenty-seven plates, the anterioi* twelve of which have been 

 in use. Precisely the same disposition of the dental sub- 

 stances is obsei-ved in this case as in the upper grinder, and 

 they are developed in the same relative proportions. The 

 vertical height of the plates is still greater than in the cor- 

 responding lower molar of E. Hysudricus. The upper surface 

 is concave, and the under very convex. The anterior plates 

 are nearly vei-tical, while the posterior gradually slope back- 

 wards till they become almost horizontal in the hmdmost 

 portion, with a eoiTesponding gradual diminution in their 

 heio'ht. This is a mechanical arrano-ement arisinsr from the 



a Oct 



contracted diameter of the posterior part of the dental canal, 

 in which the back part of the tooth is developed, close under 

 the condyle, the plates being disposed so as to occupy the 



