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PALAEONTOLOGY. 



skeleton, now complete in the British Museum, measures 18 

 feet ; its dentition agrees as to number and kind of teeth 

 with that of the sloths (Bradypus). But the molars (fig. 167) 

 are longer, more deeply implanted, of more complex structure, 

 and with grinding surfaces of the bilophodont type. The 



d ^3 

 Fig. 167. 

 Section of upper molar teeth, Megatherium (one-third nat. size), Pleistocene, 

 South America. 



elephants, which subsist on similar food to that of the Mega- 

 therium, had their grinding machinery maintained by a nume- 

 rous succession of teeth : the same end was attained in the 

 Megatherium, by a constant growth and renovation of the 

 same teeth. The formative pulps were lodged in the deep 

 basal cavities, exposed in the section figured (fig. 167, p). The 

 molar teeth were five in number on each side of the upper 

 jaw, and four in number on each side of the lower jaw (fig. 

 168). In this bone the fore part is much prolonged, and 

 grooved above, to support a long, cylindrical, powerfully mus- 

 cular tongue, by which the Megatherium, like the giraffe, 



