( 136 ) 
Little Salmon River. I refer specimens here with rather 
narrower leaves more closely placed on stems and branches 
than in the preceding (717). 
Brachythecium albicans (Neck.) B. & S. Skagway, on 
rock. Sterile (797). 
Brachythecitum Starkei (Brid.) B.& S. Lake Lindeman. 
In these specimens the costa extends about 2 up or is shorter 
and double (719). 
Brachythecium reflexum Starke. Lake Lindeman (718). 
Brachythecitum Idahense R. & C. Dawson, on earth and 
rock. This species is evidently most closely related to coll- 
num from which it is distinguished principally by the nar- 
rower leaves. The costa of the leaves near the ends of the 
branches terminate in a spine, with the leaf surface on either 
side papillose by the projecting upper ends of the cells. This 
roughening of the back of the leaf occurs in collinum, but 
to a less degree and it makes these two species close to those 
of Bryhnia, or rather, brings those species almost too close 
to Brachythecium, it would seem. The perichaetial leaves 
of both collénum and Jdahense are somewhat variable, usually 
rather abruptly acuminate with one or two coarse teeth at 
base of acumen (720). 
BRACHYTHECIUM PETROPHILUM R. S. Williams sp. nov. 
In low, dense tufts or sometimes in thin mats with long 
creeping stems and short subpinnate branches. Stem leaves 
1.5 mm. long by .¢ mm. wide, narrowly ovate-lanceolate, 
about one-half costate, serrulate all round, more or less de- 
current and margin reflexed near base, not very concave and 
scarcely or not plicate. Median leaf-cells linear flexuous up 
to .065 mm. long and .oo5 mm. wide. Alar cells short and 
broad not forming a distinct cluster. Branch leaves very 
similar to stem leaves but mostly a little smaller, with longer 
costa ending in spine on back and adjacent cells sometimes 
papillose by the projecting upper ends. Inner perichaetial 
leaves pale, ecostate, gradually narrowed to a slender, flexu- 
ous, serrulate point, with rarely 1 or 2 coarse teeth at its base. 
Capsule nodding, curved, with lid about 2.5 mm. long and 1 
mm. broad. Lid conical, its height about equal to basal di- 
