

MAP. 



The portion of the accompanying map south of the forty-ninth parallel is based mainly on the map of this 

 region by Stiilpnagel and Berghaus in Stieler's Hand-Atlas ; the portion north of the forty-ninth parallel 

 is based on Johnson's map and recent surveys, including Mr. W. H. Dall's map of Alaska and adjoining 

 regions, recently published by the United States Coast Survey. 



Owing to the influence the overland emigration and the construction of the different railroads across the 

 Plains have had in restricting the range of the Bison, the course of the overland trail and the Union Pa- 

 cific and Kansas and Colorado railroads has been laid down on the map. The routes of De Soto and 

 Coronado have been added on account of their historic interest in connection with the former range 

 of this animal, the former being from Schoolcraft's map of De Soto's route (Hist., Cond., and Pros, of 

 Ind. Tribes of U. S., Part III, PI. xliv), and the latter from Mr. R. H. Kern's map of Coronado's 

 route, published also by Schoolcraft (Hist., Cond., and Pros,, etc., Part IV, PI. iii). 



In order to better adapt the ma]) to the illustration of the geographical distribution of animal anil vege- 

 table life (tin- need of such a map being apparent), isothermal lines have been added, based on Mr. C. 

 A. Schott's Temperature Charts of the United States ; permission tor their use being kindly granted by 



Professor •' ph Henry, Secretary of the Smithsonian Institution, under whose direction they were 



prepared. Only the lines of mean annual temperature have been extended across the continent The 



i-orlirini.il anil isotlirr.il curves, owing to their great complication over the more broken country to 



the westward of this limit, are carried mere!} from the Atlantic coast to the eastern base of the Rock; 



Mountains. 



