CH. l] RANGE OF SLOTHS AND ANTEATERS. 31 



and more unlike each other ; hence the differences between 

 the Cracidse and Megapodidse. We find in fact the 

 presumably younger race spreading over the whole earth, 

 while the remnants of the older race are limited to the 

 more remote parts. All this fits in well, as will be 

 remarked later, with the Polar theory of the origin of life. 



Distribution of the Edentata. 



The Edentata are a group of mammals in which 

 the distribution has a very strong relation to anatomical 

 structure. That there is this intimate connection has 

 been shown by recent anatomical investigation, which 

 is summed up and its purport explained in a paper by 

 Sir William Flower 1 , from which the information upon 

 the subject can be most conveniently got. Formerly the 

 members of this group were divided into families not at 

 all consistent with deep lying structure but rather with 

 superficial modification depending upon similar habits 

 and ways of life. Before examining the rational classifi- 

 cation of the group as proposed by Sir William Flower, 

 it will be convenient to briefly pass in review the different 

 genera and families into which the Edentata may be 

 divided. 



The living members of the group readily separate into 

 five families, which are the following : Bradypodidse, or 

 sloths, containing the two genera Bradypus and Cholcepus. 



Myrmecophagidse, or anteaters, with the genera Myr- 

 mecophaga, Tamandua and Cycloturus. 



Dasypodidse, or Armadillos, with the six genera, 



1 P.Z.S. 1882, p. 358. 



