MEGATHERIUM. 117 



semble those of a Sloth. The long and broad bone, (b,) de- 

 scending the cheek from the zygomatic arch, connects it 

 more nearly with the Ai than with any other animal : this 

 extraordinary bone must have been auxiliary to the power 

 of muscles, acting with more than usual advantage, in 

 giving motion to the lower jaw (d.) 



The anterior part of the muzzle (c) is so strong and sub- 

 stantial, and so perforated with holes for the passage of 

 nerves and vessels, that we may be sure it supported some 

 organ of considerable size : a long trunk was needless to an 

 animal possessing so long a neck ; the organ was probably 

 a snout, something Uke that of the Tapir, sufficiently elon- 

 gated to gather up roots from the ground. The septum of 

 the nostrils also being strong and bony, gives farther indica- 

 tion of the presence of a powerful organ appended to the 

 nose; such an apparatus would have afforded compensation 

 for the absence of incisor teeth and tusks. Having no in- 

 cisors, the Megatherium could not have lived on grass. The 

 structure of the molar teeth (PI. 5, Fig. 6 — 11, and PI. 6, 

 No. 1, shows that it was not carnivorous. 



The composition of a single molar tooth resembles that of 

 one, of the many denticules, that are united in the compound 

 molar of the Elephant ; and affords an admirable exemplifi- 

 cation of the method employed by Nature, whereby three 

 substances, of unequal density, viz. ivory, enamel, and crusta 

 petrosa, or cxmentum, are united in the construction of the 

 teeth of graminivorous animals. The teeth are about seven 

 inches long, and nearly of a prismaticform (PI. 5, Fig. 7. 8.) 

 the grinding surfaces (PI. 5. Fig. 9. a. b. c. and PI. 6, Z. a. 

 b. c.) exhibit a peculiar and beautiful contrivance for main- 

 taining two cutting wedge-shaped salient edges, in good 

 working condition during the whole existence of the tooth; 

 being, as I before stated, a modification of the contrivance 

 employed in the molars of the Elephant, and other herbivora. 

 The same principle is applied by tool-makers for the 'pur- 

 pose of maintaining a sharp edge in axes, scythes, bill-hooks. 



