102 MOSTLY MAMMALS 



are concerned, as closely allied to the sloths. It may be 

 added that the great divergence of the two series of 

 teeth in the mylodon skull indicates the presence during 

 life of a tongue of great width and size. Mylodons had 

 a number of ossicles, like large beans, embedded in the 

 outer surface of the skin ; but in the nearly allied 

 glossothere, of which portions of skin covered with long 

 sloth-like hair have been discovered in a cave in Pata- 

 gonia, nearly similar ossicles were embedded in the inner 

 side of the skin. Strange to say, these ground-sloths 

 appear to have been kept in caves as domesticated 

 animals by the ancient inhabitants of Patagonia. 



Thus far I have shown how the ground-sloths are 

 related to the sloths in the characters of their skulls ; 

 but other members of the group, known as the scelido- 

 theres (Scelidotherium), although still retaining the same 

 number of teeth, present a certain approximation in these 

 respects to the ant-eaters. Thus their skulls, instead of 

 being short and broad like those of the mylodons, are very 

 long and narrow, and have the muzzle much produced in 

 advance of the anterior teeth. Indeed, it would require 

 only a still greater elongation and narrowing of the skull 

 of a scelidothere, coupled with the total loss of the 

 teeth, to produce one very similar to that of an ant-eater. 



So far as I am aware, palaeontologists have not yet 

 been able to trace a complete transition from the gigantic 

 ground-sloths of the Pleistocene deposits of Buenos Aires 

 to their diminutive representatives from the older Tertiary 

 deposits of Patagonia, although it is known that some of 

 the species from the intermediate formations were inferior 

 in point of size to their more recent allies. It is, how- 

 ever, very interesting to find that the pigmy ground-sloths 

 of these Patagonian deposits had transversely ridged 



