Central Part of British North America. 239 
Silene acaulis, L. Castelleja minuta, Doug. 
Cerastium alpinum, L. Polygonum viviparum, L. 
arvense, L. Oxyria reniformis, Hook. 
Stellaria longipes, Gold. Salix reticulata, Z. var. nana, Andr. 
Fragaria virginiana, Ehr. —— arctica, R. Br. 
Potentilla fruticosa, Z. . Allium Scheenoprasum, C. 
diversifolia, Lehm. Ligadenus chloranthus, Rich. 
Kpilobium alpinum, L. Juncus ensifolius, Wick. 
arcticus, Wick. 
castaneus, Sm. 
Saxifraga bronchialis, L. 
controversa, Sternb. 
Dahurica, Pall. | Luzula parviflora, Duv. 
Parnassia fimbriata, Hook. spicata, L, 
Sedum stenopetalum, Pursh. Poa alpina, L. 
Youngia pygmea, Ced. pratensis, Z. 
Senecio triangularis, Hook. Phleum pratense, L. 
Erigeron compositum, Pursh. Bromus ciliatus, LZ. 
Valeriana capitata, (?) Willd. Trisetum subspicatum, P. de B. 
Menziesia grandiflora, Hook. Festuca ovina, L. 
Cassiope tetragona, G. Don. Calamagrostis (Desyeuxia) coarc- 
Gentiana propinqua, [ich. tata, Torr. 
On commencing the descent of the slope to the west, the 
change in the nature of the vegetation is very marked, showing 
a great increase in the amount of moisture which is deposited. 
Thus, high up on the sides of the valleys, there are dense 
thickets of Alnus viridis, which grows to the height of six and 
eight feet, with sturdy stems and branches. In the valleys, 
the forest is quite choked by an undergrowth of Thuja occi- 
dentalis, Mahonia Aquifolium, Panax horridum, Pyrus ame- 
ricana, Viburnum Opulus, along with species of Vaccinium, 
Ribes, Rubus, Symphoricarpos, and many other plants not 
observed on the eastern slope of the mountains. Wherever 
the valleys are rocky, the rocks are covered by a close growth 
of mosses and ferns, both of which groups are almost wholly 
wanting on the east side, excepting those mosses that grow in 
swamps. ‘The forest is often impenetrable, from the interlock- 
ing of the trunks of fallen trees, many of which are three and 
four feet in diameter. When travelling with horses, it is 
difficult, where there is no trail, to get on faster than a mile 
or two a-day; and to make matters worse, amidst all this 
luxuriance of vegetation there is nothing that the poor animals 
can eat excepting a scanty growth of Hquisetum, of which they 
are yery fond, and which grows on the shingle flats of the 
