20 6 Charles Darwin. 



as we go back into the ages we find equines with 

 lateral digits and hooflets becoming larger and 

 longer, teeth shorter and more generalised, skel- 

 etons less characteristic ; rhinoceroses with cutting 

 teeth, and more slender forms ; tapir-like animals 

 without the peculiar tapirine teeth, with rhinocero- 

 toid skulls, and with otherwise modified structure ; 

 all these, accompanied by innumerable other modi- 

 fications, till finally we are almost at a loss to tell 

 whether it is a horse-like, a rhinocerotoid, or a tapir- 

 oid animal that is before us, and they become lost in 

 earlier forms with special characters of their own. 

 And as we go still further back we are confronted 

 with still other forms that are connected by series 

 projected backward from the ruminants and from 

 the elephantids. We do, in fine, know the geneal- 

 ogy of our own contemporaries imperfectly, it is 

 true, but still we know it. 



It was objected that animals were segregated by 

 such very wide intervals that they must be isolated 

 in different branches, and that there could be no 

 community of structure between such branches ; 

 they expressed fundamentally different plans of 

 structure. 



One by one zoology, anatomy, and embryology 

 supplied the links between the old branches; the 

 branches were at length completely uprooted, and 

 it has even become a matter of simple convention 

 what should be considered major groups. Plans of 

 structure can no longer be claimed to be peculiar to 

 different types. 



That branch of which man is the primate the 



