LETTER OF TRANSMITTAL. 



U. S. Depaetment of Agkiculture, 



Biological Survey, 

 Washington, D. C, June 20, 1898. 

 Sir: I have the honor to transmit herewith for publication, as Bul- 

 letin No. 10 of this division, a report on the work of the Biological 

 Survey in its relation to practical agriculture, comprising a reprint 

 of the article on the subject in the Yearbook of the United States 

 Department of Agriculture for 1897 and considerable additional mat- 

 ter. This report is accomj)anied by a new map of the life zones of 

 the United States, corrected to December, 1897, and consists of four 

 parts, as follows: 



I. Relations of the Biological Survey to iDractical agriculture. 

 II. Life zones of the United States : Boundaries, native species, and 

 important crops. 



III. Laws of temj)erature control of the geographic distribution of 

 animals and i^lants. 



IV. Crop tables. 



It is hoped that this report, with its accompanying zone map and 

 crop lists, will serve to emphasize the extreme wastefulness of indis- 

 criminate exiDcrimentation, by which hundreds of thousands of dollars 

 are thrown away each year in futile attempts to make crops grow in 

 areas totally unfitted for their cultivation. 

 Respectfully, 



C. Hart Merriam, 



Chief, Biological Survey. 

 Hon. James Wilson, 



Secretary of Agricultwre. 



