NATURAL SELECTION CRITICISED. 249 



it propos of the armadillos. " The little armour-plated 

 Armadillos," says .Nicholson in his Manual (p. 672), "are 

 represented by the colossal Glyptodon." The enormous 

 disproportion between the past and the present may be 

 understood from this, that, while the last-named monster 

 measured " more than nine feet from the tip of the snout 

 to the end of the tail," it is rare at the present day to 

 meet with any armadillo over two or three feet in length," 

 and there actually exists one (p. 587), the Chlamyphorus 

 truncatus, " the total length of which is only about six 

 inches ! " Notwithstanding the disproportion between 

 the past and the present, still it was the obvious resem- 

 blance common to both that irresistibly convinced Mr. 

 Darwin of the indubitable descent of the one from the 

 other. 



2. The point here is that, in the range southwards of 

 South America, the different habitats have indeed different 

 animals as occupants ; but, nevertheless, all these different 

 animals are still " closely allied." Closely allied the one 

 to the other, they seem only " to replace " each other. 

 And in this way, here, too, a common descent irresistibly 

 suggested itself to Mr. Darwin. 



3. " The South American character of most of the pro- 

 ductions of the Galapagos Archipelago, and more especially 

 the manner in which they differ slightly on each island 

 of the group." 



Under all three numbers, then, and we simply assume 

 the truth of the facts, we have the conclusion to com- 

 munity of origin from similarity in difference, at least as 

 a problem suggested. But the strange thing is that, let 

 the similarity point to what identity it may, the idea origin 

 is, accurately, no constituent of suggestion under any one 

 of the three numbers. 1. Certain extinct fossils resemble 

 certain living animals ; 2. successive habitats in latitude 

 have closely allied occupants; 3. in a certain given 



