III.] GROUND-SLOTHS. IO5 



animals, but their structure is not in favour of this view, and it 

 must be remembered that their remains are likewise met with in 

 Brazil, which was probably always as well wooded as at the present 

 day. The disappearance of forests from the pampas cannot, in- 

 deed, be regarded as more marvellous than the extinction of its 

 Plistocene mammals. In the sand-dunes near the coast at Buenos 

 Aires bones of some of the ground-sloths, as well as of glyptodonts, 

 have been found in association with human remains, so that their 

 extinction is an event of comparatively recent date. The genus is 

 typically represented by Mylodon harlani of the Plistocene of 

 Kentucky and other parts of North America, but is nevertheless 

 essentially South American, ranging in Argentina from the Pam- 

 pean beds to those of Parana and Monte Hermoso. The allied 

 genus Megalonyx is exclusively restricted to the North American 

 Plistocene and Upper Pliocene ; and here may be repeated the 

 observation that the absence of remains of these ground-sloths 

 from the Miocene of North America, coupled with their presence 

 in the Santa Cruz beds of Patagonia, clearly indicates that they are 

 late immigrants from the south into the northern half of the 

 continent. , 



Nearly allied to Mylodon, the genus Glossotherium from the 

 Plistocene of Argentina and Uruguay serves to connect it with 

 another generic representative of the family known as Scelido- 

 therium. In place of the comparatively short skulls of the 

 mylodons, the species of this genus have the muzzle of the skull 

 greatly elongated, so that there is a long toothless space in 

 advance of the dental series ; and whereas the skulls of the species 

 of Mylodon are essentially sloth-like, those of Scelidotherium show 

 a marked approximation to the anteater-type. The species of 

 Scelidotherium are of medium or rather small size ; and in space 

 the genus ranges from Patagonia, through the Argentine, to Brazil, 

 Bolivia, and Chili ; while in time it extends from the superficial 

 sand-dunes and Pampean deposits to the lower Tertiaries of 

 Parana, Monte Hermoso, Catamarca, and Santa Cruz, with a 

 gradual decrease in the size of the species as we descend in the 

 geological scale '. Nearly allied is the genus Catonyx, from the 



1 The Santa Cruz form has been quite unnecessarily separated under the 

 name of Analcithermm. 



