500 



Causes and Course of Organic Evolution 



If in addition to other general mammalian characters the 

 above existing marsupials and lemurs show so many contact 

 structural details, it might be expected that the above-named 

 fossil genera would even more exactly bridge over the gap. 

 Such they effect in various ways. So, from higher urodeles 

 to the primitive polyprotodont marsupials, from these to the 

 phalangerid diprotodonts, and from these again to proto- 

 lemuroids, the transition seems fairly continuous and sug- 

 gestive. 



But here we would not insist too closely on direct descent 

 of the lemuroids from phalangerid ancestors. For given 

 certain polyprotodont ancestral characteristics as a common 

 starting point for further evolutionary advance, fairly similar 

 groups of environal factors may have combined to evolve 

 from such common ancestry an arboreal lemuroid line, and 

 a phalangerid line of ascent that sinmltaneously diverged from 

 each other in certain fundamental structural features. 



But Haeckel and Cope have both advocated the ^^ew that 

 the lemurs are very directly related to the higher monkeys. 

 Thus Cope says (73: 154): "I have advanced the . . . 

 hypothesis that the Anthropomorpha (which include man and 

 the anthropoid ai)es) have been derived directly from the 



