IV 



lull to complete the work in various groups in cases where specialists are 



prepared to do so. 



Other monographs are in an advanced state of preparation, based on 



the collections of the Survey, which will be printed as soon as they can he 



rendered more complete by farther investigations in the field. 



Very respectfully, your obedient servant, 



F. V. HAYDEN, 



United States Gi-ologist. 

 lion. Z. Chandler, 



Secretary of the Interior. 



. 



