LEHER OF TRANSMITTAL. 



U. S. Department of Agriculture, 



Bureau of Entomology, 

 Wmlmigton, D. C ., March 11, 1908. 

 Sir: I have the honor to transmit herewith the manuscript of a 

 revision of the Ixodoidea, or ticks, of the United States, by Mr. Nathan 

 Banks, assistant entomologist in this Bureau. In view of the impor- 

 tance which some of the ticks have assumed as the known transmitters 

 of certain diseases it becomes very necessary that the different species 

 be distinguished with certainty. This has hitherto been a matter of 

 great difficulty, since there has been no work of a systematic character 

 dealing with all the known species of ticks occurring in the United 

 States. To supply this need and as a basis for the life history work 

 undertaken by this Bureau on the cattle tick and other ticks, this 

 bulletin has been prepared. I recommend its publication as Technical 

 Series No. 15 of the Bureau of Entomology. 



Respectfully, L. O. Howard, 



Entoniolofjht and Chief of Bureau. 

 Hon. James Wilson, 



Secretary of Agriculture. 



