The Monteregian Hills. 245 



differentiation as an explanation of the origin of these and 

 similar groups of rocks, arising not only from the repeated 

 association of the various members of the group at man}' 

 centres in a single area like that described in the present 

 paper, but also at centers widely separated from one 

 another in different parts of the world. The occurrences 

 described by Ramsay 1 in the Kola peninsula may be 

 especially noted in this connection as closely allied to 

 those of the Monteregion hills, a soda-syenite (umptekite) 

 occurring about the margin of an intrusion of the 

 nepheline-syenite which constitutes the massive, while 

 theralite is also found as a differentiation product of the 

 .same intrusion. 



The author desires to acknowledge his indebtedness in 

 connection with this investigation to Miss Rosalind 

 Watson, of Victoria, B. C, who, when a student at this 

 university began the study of Mount Johnson ; also to 

 Professor Rosenbusch, Professor Iddings, and Professor 

 C. H. McLeod for valuable aid during the course of the 

 work. 



Feank D. 4- dams - 



McGill University, 

 Montreal. 



1 Des Nephelinsyenityebitt auf ' der Halbinsel Kola. Fennia 11, No. 2. 

 Helsingfors, 1894. 



