18 



changes of climate in general, with special reference to the arid 

 region of the United States. This part of the work naturally 

 connects itself with the previously published volume of the Sturgis- 

 Hooper Professor, which appeared in the Memoirs of the Museum 

 twelve years ago, and bears the title of " The Climatic Changes 

 of Later Geological Times : a Discussion based on Observations 

 made in the Cordilleras of North America." 



