Explanatory ^ote 



The series embodies results of investigations, usually of restricted 

 scope, intended to aid or direct management or utilization practices and as 

 guides for administrative or legislative action. It is issued in limited 

 quantities for the official use of Federal, State or cooperating agencies and 

 in processed form for economy and to avoid delay in publication. 



Washington, D. C. 

 April, 1950 



Interior - Duplicating Section, Washington 25, D.C. 



