356 Part IV. Chapter ı. 
Several species of Eguisetum grow abundantly in the shallow water and often 
on the banks of streams Rhamnus alnifolia, Lonicera glaucescens, Elaeagnus 
argentea, Viburnum pauciflorum, Shepherdia (Lepargyraea) canadensis occur. 
Pinus Banksiana and Betula papyrifera reach their northern limit near the 
confluence of Hill and Fox rivers; as also the aspen Populus tremuloides. 
Swamp Formation. Back from the rivers are mossy swamps in which 
the vegetal growth consists of Empetrum, Ledum latifoltum, Betula glandulosa 
and associated species '). 
C. Mackenzie District. 
_ The southern boundary of the subarctic forest of the Mackenzie District 
is marked by the northern extension of the prairies. It runs, as follows: From 
near the junction of the north and south forks of the Saskatchewan River, it 
passes southeasterly by the sources of the Red Deer and Assiniboine, and 
over the southwestern slopes of Duck and Riding mountains to the south end 
of lakes Manitoba and Winnepeg. 
Coniferous Forest Formation. The shores of the Athabasca River are 
covered, according to EDWARD A. PREBLE?), with a fair growth of black and 
white spruces (Picea nigra — mariana and P. alba = canadensis), Banksian 
pine, balsam (Adies balsamea), tamarack (Larir americana), balsam poplar 
(Populus balsamifera), aspen (P. tremuloides) and canoe birch (Bertula papyri- 
fera). Of these species Pinus Banksiana and Larir americana are the least 
abundant, the former growing only on certain elevated points, and the latter 
being a tree of ii sphagnum bogs, rarely appears on the immediate banks 
of the river. 
Various shrubs are found and form an undergrowth in the forest. Such are Juniperus nana, 
J. sabina, various species of willows (Salix Bebbiana ete.). Alnus incana, viridis (= A. alno- 
betula), Ribes rubrum, R. oxyacanthoides, Rosa acicularis, Amelanchier alnifolia, Shepherdia cana- 
densis, Elaeagnus argentea, Cornus stolonifera, C. canadensis, Prunns pennsylvanica, Viburnum 
paueiflorum, V, opulus, Lonicera ir Sean = involucrata, Symphoricarpus racemosa and occi- 
dentalis. 
The country at the outlet of Great Bear Lake is undulating and, Be 
for certain semibarren places near the shores of the lake, is well wooded with 
Picea, Larıix, and the usual subarctic vegetation. Much of the ground is covered 
with lichens of the genus Gyropkora and various mosses. On September ı6th, 
PREBLE noticed that the leaves of the larches and other deciduous trees were 
falling. Elsewhere along the Mackenzie River, the forests of Picca nigra 
(mariana) and P. alba (canadensis) are filled with an undergrowth consisting 
of Rosa acıcularis, Rubus strigosus, Viburnum pauciflorum, Vaccinıum uligino- 
sum, Ribes rubrum and Pprostratum. As the northern limit of trees is reached, 
x) ni EDwarD .A.: A biological Investigation of the Hudson Bay Region. ges: 
American Fauna No. 22: 1902, 
=. 2) A: Biological: Investigation & the. Athabasca -Mackenzie Rögion, Nortb American Fauna 
No. 27, 86: 1908, Re Ar 
