nder 



cixcuinheT 



Fig. 252. Genealogical tree of animal life 



This diagram is intended to suggest the common origin of all animal forms, with the 



constant progressive departure from ancestral types, now in one direction and now in 



another, like the branching of a tree. Of course only the main branches are shown. 



There are probably over a million species of animals living to-day (cf. Fig. 251) 



