The Species of the Genus Larix. 87 
Agric. No. 680, 1918, Map 7) are very improbable, and we 
have been unable to discover any evidence in support of 
them, either in the shape of other records or specimens 
from Baffin Land. 
Within such wide bounds, it is only natural that the 
tree should vary somewhat in growth from the good to 
the poor localities, and from south to north, but it seems 
otherwise to be a very uniform species, varying but little 
morphologically. It attains its best development on well- 
drained ground around the Great Lakes, but here, just as 
elsewhere within the wide bounds of its occurrence, it is 
not the dominating tree where the soil is richer and also 
appeals to other more shadow-enduring species. Most 
frequently it will be found relegated to low-lying, damp 
soil, where other trees cannot follow it, and also in the 
extreme north it becomes the dominating tree. It succeeds 
in thriving and forming extensive, dense forests even in the 
very damp areas. In the north it reaches the extreme 
forest-line together with Picea mariana, P. canadensis, and 
other species of trees, or it is found forming the forest-line 
alone. In the most northerly localities, where it grows 
together with others, it is the most vigorous species, suc- 
ceeding in developing as a small tree when other kinds 
only manage to exist as creeping, stunted individuals. With 
regard to temperature and humidity, L. laricina is capable 
of growing under very widely differing conditions. HUTCHIN- 
SON States its powers of existing with or without water to 
be three times as great as those of Alnus incana (Hur- 
CHINSON, 1918, p. 482). 
On marshy ground and in the extreme north, it certainly 
does not grow as large as in the best localities, but on the 
marshes in the southern portion of the area it can still 
