TABLE OF DISTRIBUTION OF CARICES. 345 



Pennsylvania Lam. Saskatsckawan, Winipeg, and Cumberland 



Lakes, 

 incurva Light. Valleys of the Sask. and Mack. 

 Of the above, C. Raeana is new, and C. stans new to British 

 America. 



I find from my notes that the number of Carices in North 

 America is 250 ; of which 178 are found in all Arctic America, 

 including 97 common to Arctic America and the States, leaving 

 81 Arctic species. 



Of these 81, there are 36 common to Europe, leaving 45 

 peculiar to Arctic America. 



Of the 97 found in Arctic America and the States, 28 are 

 common to Europe, leaving 69 exclusively American. 



There are in the States, besides, 72, of which 4 only are Eu- 

 ropean, leaving 68 exclusively American. 



The exclusively American species are therefore 182, and 68 

 common to America and Europe. 



You will find that the large proportion of Carices in the 

 Northern part of America, common to it and to Europe, is in 

 accordance with the observations of Agassiz, made in his late 

 interesting excursion to Lake Superior. He remarks that the 

 farther north we proceed the greater is the uniformity of the 

 plants common to the two continents ; and it is remarkable 

 that Leconte, in his list of the Coleoptera of Lake Superior, was 

 struck with the absence of all the groups peculiar to the Ame- 

 rican continent, the large increase of the species of genera 

 feebly represented in the more temperate regions, and the ex- 

 istence of many genera heretofore regarded as confined to the 

 southern parts of Europe and Asia. 



Yours sincerely, 



F. BOOTT. 



