354 THE CANADIAN NATURALIST. [June 



Mountains of New England, or to Greenland and the Rocky 

 Mountains, which have not hitherto been found elsewhere. 

 They are : — 



Draba aurea (Rocky Mountains). 



Arenaria Grcenlandica (White Mountains northward to Labrador), 



IV. — ON THE ARCTIC PROPORTIONS OF SPECIES TO GENERA, 

 ORDERS, AND CLASSES. 



The observations which have hitherto been made on this subject 

 are almost exclusively based on data, collected on areas too small 

 to yield general results. Especially in determining the influence 

 of temperature in regulating the proportions of the great groups of 

 flowering plants, it is of the highest importance to take compre- 

 hensive areas, both because of the wider longitudinal dispersion of 

 some orders, especially the Monocotyledons, and the effects of 

 local conditions, such as bog land, which determine the over- 

 whelming preponderance of Cyperacese in some arctic provinces 

 compared with others. 



The proportion of genera to species in the whole arctic phaeno- 

 gamic flora is 323 : 762, or 1 : 2-3 (Monocot., 1:28; Dicot., 

 1 : 2-2); and that of orders to species 1 : 10*8; in the several 

 provinces as follows : — 



Gen. 



Arctic Europe 277 



" Asia 117 



" West America 172 



" East America 193 



" Greenland 104 



Thus Europe presents the most continental character in its 

 arctic flora, and West America the most insular ; which may be 

 attributable to the same cause in both ; namely, the uniformity or 

 variety of type. In West America we have, as in an oceanic 

 island, a great mixture of types (Asiatic, European, East and 

 West American) and paucity of species ; in Europe the contrary. 

 The proportions of species to orders are still more various ; but 

 here, again, Europe takes the lead decidedly. 



The proportions of genera and orders to species of all Greenland 

 differ but little from those of its arctic regions ; whereas the 

 contrast between Arctic Europe and this, together with Norway 

 as far south as 60° N. lat., is very much greater. This is in 

 accordance with the observation I have elsewhere made, that the 



