ELEPHANT AND MASTODON. 43 



molar of E. Ui/sudricus, bearing but a very slender proportion 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 co- 

 ronal surface of the unworn portion. This specimen is 8.2 inches 

 in length. 



Fig. 2 b represents the section of a very fine specimen of the 

 last inferior molar of the existing Indian Elephant of Assam, from 

 the collection at the India House. It is an unusually large speci- 

 men, showing as many as twenty-seven plates, the anterior twelve 

 of which have been in use. Precisely the same disposition of the 

 dental substances is observed 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 corresponding 

 lower molar of E. Hysudricus. The upper surface is concave, 

 and the under very convex. The anterior plates are nearly 

 vertical, while the posterior gradually slope backwards till they 

 become almost horizontal in the hindmost portion, with a corre- 

 sponding gradual diminution in their height. This is a mechanical 

 arrangement arising from the 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 least vertical space. The basal mass of ivory 

 between the plates and the fangs is reduced to a small quantity. 

 This tooth measures 15^ inches long in a straight line. 1 



Fig. 1 represents a section of the last upper molar of E. primi- 

 genius, from an English specimen in the museum of the Geolo- 

 gical Society, found near Kingsland. We arrive here at the last 

 link in the chain of modifications, exhibited by the molar of the 

 typical Elephants. The section bears a close resemblance to that 



1 The artist has drawn this figure reversed, as compared with the other sections, the 

 worn end of the tooth being to the right. The same remark applies to fig. 6 a of pi. 2. 

 In pi. 1 the Indian Elephant has been named in the reference E. Asiaticus (Blum.) 

 instead of E. Indicus. 



