120 THE MAMMALIA. 



cestors of the living Brazilian Sloths. The ex- 

 pression so frequently used in illustrating the 

 relation, that the sloths of the present day are the 

 pygmean remains of the family which attained a 

 colossal development in the Diluvium, would be 

 wholly misunderstood were we to regard the 

 Bradypodae as crippled Megatherioids which had 

 taken refuge in trees. In both cases the limbs 

 have attained extreme formations which exclude 

 every thought of their having been transmitted the 

 one to the other ; and we are again referred to a 

 primary form that lies beyond all the palseonto- 

 logical discoveries yet made. 



The existing Girdled-animals and the Diluvial 

 Glyptodons resemble one another less in structure 

 than in size. But also in the group of the burrow- 

 ing and grubbing Armadilloes (which live on worms 

 and insects) one is tempted to set too little value 

 upon the length of time necessary for their origin 

 than a careful consideration of the divergences 

 would warrant. Thus the Girdled-mouse, Chlamy- 

 dophoms, a native of La Plata, differs so much 

 from the girdled-animal proper, the Dasypus, in 

 spite of the most obvious relationship, that there 

 must be between them a whole series of transitions ; 

 and hence probably one or two geological periods 



