TEMPERATE ELOEAS 



33 



Turning now to N'orth America, the following figures from 

 the latest authorities have been supplied by my friend Mr. 

 J. D. A. Cockerell : — 



state. 



Montana and Yellowstone 



Park 



Nebraska 



Colorado 



California 



Area, 

 Square Miles. 



150,000 



118,000 

 104,000 

 158,000 



No. of 

 Species. 



1934 



1478 

 2872 

 2700 



Remarks. 



Data in 1900 



1898 

 1900 

 " recent 



Two subdivisions of the eastern United States show well the effects 



of latitude. 



The number of species in proportion to area and position 

 is apparently less than in Europe, though the corresponding 

 latitudes are farther south. Germany and Switzerland com- 

 bined, with an area less than one-third of the north-eastern 

 and central States, have about as many species ; while Erance, 

 in about the same average latitude, but with less than one- 

 third the area, has considerably more. The south-eastern 

 States extending to 30° S. lat. have about the same number 

 of species as Europe from the Alps and Carpathians south- 

 ward, while the area of the latter is very much smaller and 

 its latitude about eight degrees farther north. 



The whole Mediterranean flora was estimated bv Griesbach 

 and Tchikatcheff, in 1875, to comprise 7000 species in an area 

 of about 550,000 square miles ; so that the best comparisons 

 that we can make between large European and American areas 

 show a decided superiority in the former. This is no doubt 

 partly due to the much severer winter climate in correspond- 

 ing latitudes of !N'orth America ; and perhaps the long per- 



