48 



Primitive Man. 



latter but few species remain. But the placental mammals 

 of the Eocene differ so widely from the mammals of to-day 

 as not to be recognized as related, in succession, to the 



latter, except through careful and experienced scientific 

 research and classification ; and the difference consists, 

 mainly, in their far closer relationship among themselves, 

 in structure, than among existing orders and species. In 



