232 SOCIAL EVOLUTION 



reference as it has been advanced since ' ' The Principles ' ' 

 Avas published, and is taken Avith Professor Giddings' per- 

 mission from notes of his lectures at Columbia University.) 



Keane, a. H. — Ethnology. 



Ripley, W. Z. — Tlic Races of Europe. 



Sergi, G. — The Mediterranean Race. 



Tylor, E. B. — Anthropology. 



