;r_> 



Nr. :r c H. Ostenfeld: 



cross the ikuiow Sniitli Sound lo liif^lclield L;iiul, but have 

 nol as yet exleiKied larther. Mii}H(irli(i Hossii and Hcsiieris 

 l'dlldsii are lound nol only in arctic America, l)nl also in 

 llu' arclic islands norlli ol lauopc; il is, lio\vi'V('r, niosl 

 naUiral lo sujipose llial llicv liave imniii^raled IVoni llu' wesl. 



IX. Relation between the three phyto-geographical 

 Elements in the different Districts. 



In Tal)Ie II, the species are also divided inlo Ihree 

 j)livlo-geographical elements: high-arctic (A^), arctic in liie 

 wider sense (Ao), and suh-arctic and boreal (S), and the 

 numher of species in these three categories is stated for 

 each dislrict. 



The absolute ligures themselves reveal an inleresting 

 rcgularity; this is, however, even moro clearly apparent 

 when \ve work out the percentages as seen in the accom- 

 panying Table IV and the curves oT the graph Fig. 11 



Table IV. 



Percentaf^es of tlie '^ |)hyt()-scograi)hicnl eleiiieiils in the 



various districts. 



West South East 



\111 VU VI Va \1) 1\' 111 11 1 11 111 \y V VI Ml \lll 



57 4() 26 21 1 (i 11 1 1 1 (I .') 12 2:5 :U 12 57 



:{ii I.-) 61 55 :)i 17 1.') :5!i :i2 is iit <>g (>2 :)i :a :5<» 



1 !l ].'{ 21 :VA 12 .')! bO 67 ')2 1(5 22 1.") 12 7 4 



A,. 



Ao 



S 



Al- Ilif^h-arctif. Ao. \vc[\c srns. htl. S. Sul)-arc-tic- and horeal. 



It will be noticed that the numher of high-arctic species, 

 which amounts lo .')7 j). c. of Ihc lotal no. of species in 

 Dislrict \'1I1. lalls evenly to lp. c. in Uistrict 1 (District E II 



