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 
7 Ind. Tribes of U. 8., Part III, Pl. 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, Pl. iii). 
In order to better adapt the map to the illustration of the geographical distribution of animal and vege- 
table life (the 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 for their use being kindly granted by 
Professor Joseph 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 
isocheimal and isotheral curves, owing to their great complication over the more broken country to 
the westward of this limit, are carried merely from the Atlantic coast to the eastern base of the Rocky 
Mountains. 
