EXPLANATION OF THE PLATES. 



PLATE I. 



Side-view of the skeleton of the Mylodon rohustus, one-sixth of the natural size, 

 or on a scale of 2 inches to a foot : an outline of the skeleton of the Ai 

 {Bradypus tridactylus) reduced to the same scale, is' given at fig. 2, whereby 

 the gigantic proportions of the Mylodon, as compared with a species of its 

 most nearly allied existing genus, may be readily and accurately appre- 

 ciated. 



