SOME EXTINCT ARGENTINE MAMMALS 97 



Side by side with this well-defended creature there lived, 

 however, another not less remarkable mammal, of nearly 

 similar dimensions, and likewise belonging to the great 

 order of edentates, then, as now, so characteristic of 

 South America. This creature had, however, no such 

 coat of mail as that which defended its contemporary 

 (though there is a possibility that some bony granules 

 may have been embedded in its skin), and as it appears 

 to have been equally devoid of weapons of offence, while 

 it did not derive protection from an arboreal life, it may 

 be a matter of wonder how it managed to fight its way 

 through the struggle for existence. That it did so is, 

 however, perfectly clear, since the pigmy ground-sloth, as the 

 animal in question may be called, is clearly the ancestral 

 type from which were subsequently evolved those gigantic 

 edentates of the Pleistocene deposits of the Argentine 

 scientifically known by the names o( Megalotherium, Mylodon^ 

 etc., but which may be collectively designated ground-sloths. 

 These, although in some cases unprotected by any means 

 of defence, were among the most gigantic of mammals, and 

 they had, it is needless to say, no difficulty in holding their 

 own ; and it is only with regard to their pigmy ancestors 

 that we have any cause for wondering how they managed 

 to survive. Possibly these pigmy ground-sloths were 

 burrowing creatures, like the great ant-eater of the present 

 day, and lived in holes excavated by their powerful claws ; 

 and if this should be the case, the difficulty as to their 

 survival vanishes. 



Sloths are, however, such essentially arboreal creatures, 

 as characteristic of the Brazilian forests as are squirrels 

 and dormice of our own woods, that my readers will want 

 to know what I mean by using such an apparently contra- 

 dictory term as ground-sloths. 



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