1901.] NATURAL SCIENCES OF PHILADELPHIA. 125 



and the Nydieebidce, perhaps supports this view, but at the same 

 time well illustrates the complexity of the problem. 



If the progress of palaeontology should justify these specula- 

 tions, it seems to follow that it is likely to also demonstrate the- 

 multiple rather than the single origin of the present Lenmro idea. 



