GEOGRAPHICAL DISTRIBUTION AND DESCENT. 



191 



The bands of the latter are always movable, 

 whereas the armour of the glyptodons is 

 rigid like that of the turtles, and is entirely 

 composed of pieces joined together im- 

 movably by sutures. The only genus which 

 had a lcaigish head somewhat similar to that 

 of the armadillos, the genus Scelidotherium, 

 had no armour. 



We can thus trace neither the present 

 armadillos back to the glyptodons nor the 



megatheriums back to the sloths; but it is no 

 doubt with justice that the edentates have 

 been reckoned as a degenerate branch of the 

 ungulates. Moreover, a certain affinity to 

 the monotremes may be admitted, since they 

 approach these in the structure of the brain 

 and limbs. On the whole, however, we must 

 confess that we are so far confined, from the 

 want of an adequate basis of facts, to more 

 or less bold hypotheses. 



