ORDER EDENTATA. 1 299 



the structure and mode of arrangement of the teeth. In the upper 

 jaw the teeth are usually subtriangular or oval in transverse section, 

 and in typical species there is only a short interval between the first 

 and second tooth in each jaw, and the former is worn horizontally ; 

 but in other species there is a considerable interval between the 

 two, and the first is worn obliquely, as in certain Sloths. The 

 humerus has no entepicondylar foramen ; and in the shortness of 

 the skull and the characters of the teeth this genus approaches 

 nearer to the modern Sloths than any other member of the family. 

 The best known species is the South American Mylodon robustus 

 (fig. 1 1 69), which was smaller than Megatherium americanum, its 

 length being about 1 1 feet ; but M. armatus (the type of the so- 

 called Lestodoii), from the same country, is considerably larger. The 

 type species is M. Harlani, from the Pleistocene of " Big-bone 

 Lick," in Kentucky, North America ; while the Patagonian M. 

 Darwini is a very aberrant form, regarded by some writers as 

 generically distinct, and named Grypotherium. There are numer- 

 ous small dermal scutes, which do not articulate with one another. 

 Megalonyx^ from the Pleistocene of North America, is an allied 

 genus, characterised by the long interval between the large first and 

 the smaller second tooth, and also by the rJTesence of an entepi- 

 condylar foramen to the humerus. The type species is M. Jeffer- 

 soni, from Kentucky and Tennessee ; while M. atbensis, from the 

 Pleistocene of Cuba, has been separated by some writers under 

 the name of Megalochnus (Myomorphus). Another form hitherto 

 known as Ccetodon, but which may be named Nothr other iwn, on 

 account of the preoccupation of the former term, occurs in the Pleis- 

 tocene cave-deposits of Brazil, and agrees with Megalonyx in the 

 structure of its limbs, but has teeth of the type of those of Mega- 

 therium, although their number is reduced to - ; the type species 



considerably exceeded in size the largest Ant-eater of the present 

 day. 



The Mammals from the Lower Pliocene and Miocene of North 

 America which have received the names Moropus and Morotherium, 

 and are regarded by Professor Marsh as forming the type of a 

 distinct family of Edentates — the Moropodidtz — probably belong to 

 the Ungulate family Chalicotheriidce. 



Family Bradypodid/e. — This family is entirely confined to South 

 America, and now comprises two genera of comparatively small 

 animals which are of exclusively arboreal habits. The body is 



clothed with coarse hair ; the teeth are — in number in each jaw, 



4 

 and are of subcylindrical form, with a central axis of soft dentine, 



