44 ELEVENTH REPORT. 



TABLP: A'. — DISTRIBUTION OF THE ARCTIC-ASIA SPECIES. 



31 or 74 per pent are in common with Arctic Western America. 



31 or 74 per cent are in common with Arctic Eastern America. 



27 or 64 per cent are in common with Arctic Greenland. 



34 or 80 per cent are in common with Arctic Europe. 



5. Arctic Western America. This region shows 65 species in common with 

 Ktaadn. Their occurance in the other arctic regions maj' be had from the 

 following table. 



TABLE VI. — DISTRIBUTION OF THE ARCTIC "WESTERN AMERICAN SPECIES. 



31 or 48 per cent are in common with Arctic Asia. 



59 or 90 per cent are in common with Eastern America. 



41 or 63 per cent are in common with Greenland. 



31 or 48 per cent are in common with Europe. 



As might be expected Arctic Eastern and Western America show a striking- 

 resemblance, but a difference of 10 per cent or 65 species as noted above, 

 points strongly to the probability that the Mackenzie basin may be looked 

 upon as the division line between two distinct biota within Arctic America, 

 a distinction which becomes more and more marked to the south in Realm 

 II. In this connection it is interesting to note that of the 386 alpine species 

 of Colorado listed by Cockerell (1) only one, Vaccinium caespitosum occurs 

 upon Ktaadn a very significant fact strikingly emphasizing the strong- 

 western arctic affinity of this flora and the existence of an Eastern and 

 Western Arctic Biota. « 



II. AMERICAN REALM. 



All but the two endemic species are found within this realm and their 

 regional distribution is recorded in Table I. Of the 91 arctic species 100 per 

 cent are in common with Northeastern America while only 82 species or 90 

 per cent are found in Northwestern America. However the two regions have 

 88 common species. Of these 79 are arctic forms, while 9 are peculiar to 

 Ktaadn and the American Realm. It also appears that Northeastern America 

 possesses 27 species (24%) unrecorded from Northwestern America, i. e.. 

 the former region furnished 24 per cent of the Ktaadn flora of which 75 per 

 cent are of arctic affinity and 16.5 per cent (18 species) peculiarly American. 



1. Northeastern America. As is shown in Table I Ktaadn has 99 per cent 

 of its species in common with this region. Their further distribution is re- 

 corded below. 



TABLE VII.— DISTRIBUTION OF NORTHEASTERN AMERICAN SPECIES. 



88 or 75 per cent are in common with Northwestern America. 



70 or 59 per cent are in common with Arctic Eastern America. 



63 or 53 per cent are in common with Arctic Greenland. 



68 or 57 per cent are in common with Arctic Europe. 



66 or 56 per cent are in common with Arctic Western America. 



47 or 39 per cent are in common with Arctic Asia. 



2. Northioestern America has 91 species (75%) known to Ktaadn which 

 have the following distribution: 



