10 
James Small. 
these states are included in the “ Mexican ” region by Bentham, (I, 
7). The most important species are S. lugens, Rich., S. canus, Hook, 
and S. triangularis, Hook., which occur all along the Cordilleran 
system from California to the Arctic region, each species showing 
a number of forms and occurring sometimes as high as 12,000 ft. or, 
especially in the Arctic region, coming down to sea level. These 
three species also extend eastward to a varying degree, as far as 
Saskatchewan, Manitoba and Iowa. S. Freniontii, T. & G. does 
not extend north of British Colnmbia, but occurs further south in 
Mexico, while S', ereniophilus, Rich., which extends to the Mackenzie 
River, is confined in its southern area to the eastern spur of the 
Cordilleras. 
The northern region is covered by S. Hookeri, T. & G., which 
extends from the Arctic regions southwards only to the high 
northern Rockies. The eastern path along the Appalachian system 
is indicated by S. lobatus, Pers., which extends from Mexico to 
Florida, Carolina and Illinois, and even more clearly by S. 
suaveolens, Ell., which occurs along the mountains from Maine 
to Florida. 
The gap between the Appalachian species in the east and 
those of the Cordilleras in the west is bridged by S. aureus, L., 
which with many variations in form extends from the west coast to 
the east coast and from Newfoundland, the North-west Territories 
and Alaska in the north to Mexico and Florida in the south. Other 
species with smaller areas link up the parts of both eastern and 
western paths. 
North America to Asia and Europe —The Behring Strait 
presents no impassable barrier to fruits which can be blown long 
distances by winds of less than 4 m.p.h. and the result is a strong 
connection between arctic America and Siberia. S. Pseudo-Arnica, 
Less., extending in America from Maine and Newfoundland to 
Alaska, occurs also in northern Asia. Three other species make use 
of this “ Alaska-Siberian bridge ”: the most wide spread of these 
is S. palustris, Hook., which occurs all over the northern temperate 
and Arctic regions including Greenland. The other two are S. 
resedifolius , Less., and S. frigidus, Less.: the last like 5. Pseudo- 
Arnica occurs near the coast and in habit it is similar to that 
species. The Alaska-Siberian bridge is mentioned by many writers 
(see 55, 118, etc.). 
Asia. The first path to be noted in Asia lies along the Altai and 
Thian Shan Mountains from Siberia to Turkestan (cp. 25a). This 
