PLATE XVII. 



Fig. 1. The second upper molar tooth — natural size — of the Megatherium. 



Fig. 2. Longitudinal section of the alveolar part of the upper jaw and of the five 

 upper molars, in situ — three-fourths of the natural size — of the Megathe- 

 rium. 



Fig. 3. Transverse section of a portion of a molar tooth of the Megatherium : — mag- 

 nified 500 linear diameters. 



The letters and ciphers are explained in the text. 



