346 THE CANADIAN NATURALIST. [June 



whole region is of course far north of the isotherm of 32°, which, 

 in the longitude of its middle district, descends to Lake Winnipeg, 

 in lat. 52°. 



That portion of this province which is richest in plants is the 

 tract which intervenes between the Coppermine and Mackenzie 

 Rivers ; east of this, vegetation rapidly diminishes, as also to the 

 northward. The flora of the Boothian Peninsula, surrounded as 

 it is with glacial straits, and placed centrically among the arctic 

 islands, is perhaps the poorest of any part of the area ; those of 

 Banks Land and Melville Island to the N.W. being considerably 

 richer, as are those of the shores of Lancaster Sound and Barrow's 

 Strait, and the shores of Baffin's Bay to the north and east. * 



The phamogamic flora of Arctic East America contains 379 

 species (Monocotyledons, 92 ; Dicotyledons, 287= 1 : 3-1). The 

 proportion of genera to species is 1 : 2*0. Of these 379 species, 323 

 inhabit Temperate North America, east of the Rocky Mountains ; 

 35 the Cordillera ; and 49 Temperate or Antarctic South America. 

 Comparing this flora with that of Europe, I find that 239 (or 

 two-thirds) species are common to the arctic regions of both 

 continents, whilst but little more than one-third of the Arctic 

 European species are Arctic East American. Of 105 non- 

 European species in Arctic East America, 32 are Asiatic; leaving 

 73 species confined to America, of which the following are further- 

 more confined to the eastward of the Rocky Mountains and 

 Mackenzie River : — 



Corydalis glauca. Primus Virginiana. Urtica diofca. 



Sarracenia purpurea. Heuchera Richardsoni. Salix cordata. 



Viola cucullata. Cornus stolonifera. Populus tremuloides. 



Silene Pennsylvanica. Grindelia squarrosa. Picea nigra. 



Arenaria Michauxii. Vaccinium Canadense. Spiranthes gracilis. 



Polygala Senega. Dracocephalum parviflorum. Cypripedium acaule. 



Lathyrus ochroleucus. Douglasia arctica. Carex oligosperma. 



Rubus triflorus. Elasagnus argentea. Pleuropogon Sabini. 



Of these Douglasia and Pleuropogon are the only ones abso- 

 lutely peculiar to Arctic East America. It is a noticeable fact 

 that not one of them is found in any part of Greenland. Com- 

 pared with Greenland, the Arctic East American flora is rich; 

 containing, besides those just enumerated, no less than 165 other 



* Details of these florulas will be found in the volume of the ' Linnean 

 Journal,' under the notice of Dr. "Walker's Collections, made during the 

 voyage of the Fox. 



