126 NORTH AMERICAN FLORA [VorumE 15 
costa; costa one third to one fourth the width of the lower part of the leaf, in cross-section 
below showing 8-12 guide-cells with stereid-bands above and below, each of about two rows 
of cells of mostly uniform size; alar cells brown to hyaline, extending to the costd; lower leaf- 
cells elongate with slightly thickened and pitted or not pitted walls, becoming shorter and not 
pitted above, the upper ones about 8 « wide and from nearly square to 2 or 3 times as long as 
broad; perichaetial leaves from a convolute base rather abruptly narrowed to a slender, smooth- 
ish point as long as the clasping part: seta 1.5 em. long, finally reddish: capsule about 2 mm. 
long, oblong, curved, nodding, not strumose, furrowed when dry; annulus of mostly 2 rows of 
cells; lid conic-subulate, about as long as the capsule; peristome-teeth brown, vertically 
striate nearly to the apex, divided about one half down: spores rough, up to 25 » in diameter. 
TYPE LOCALITY: Sweden. 
_ DISTRIBUTION: Labrador to Alaska and southward to Minnesota, Montana, and British Colum- 
bia, on logs; also in Europe and Asia. 
Exsicc.: Macoun, Can. Musci 22a. 
22. Dicranum laevidens R. S. Williams, sp. nov. 
Dioicous: male plants attached to the tomentum of the fertile stems, minute, sometimes 
less than 1 mm. high, with ecostate, ovate, acute or obtuse perigonial leaves: fertile plants in 
extensive, compact, glossy, brownish-green mats; stems mostly 7 or 8, rarely 15 cm. high, 
somewhat tomentose nearly to the apex, with nearly straight leaves, erect-spreading all round: 
stem-leaves 5-6 mm. long and 1 mm. wide, from a broadly ovate-lanceolate base rather gradu- 
ally narrowed to a subtubulose, smooth or sometimes slightly serrulate, narrow point; costa 
just above the broadened base 60-100 yu wide, one eighth to one tenth the width of the leaf, per- 
current, smooth on the back, in cross-section near the middle with 5 or 6 guide-cells, a stereid- 
band above of one or two rows of cells, below of one or two rows of cells and sometimes an 
outer row of differentiated cells; alar cells brown toward the margin with hyaline cells within 
reaching nearly to the costa, the cells above elongate to the apex with more or less pitted walls, 
the median cells 8-10 » wide and 40-60 u long, those in the upper part of the leaf often much 
shorter, sometimes scarcely pitted; inner perichaetial leaves scarcely as long as the stem-leaves, 
faintly costate about one half up, from a convolute base abruptly narrowed to a smooth, 
straight point up to 2 mm. long: seta yellow or reddish, 2.5-3 cm. long: capsule oblong, 
nodding, slightly curved, 2 mm. long, furrowed when dry, not strumose, with stomata in 
mostly one row near the base, the exothecal cells with unequally thickened, somewhat pitted 
jJateral walls; annulus large, of 2 or 3 rows of cells; peristome-teeth reddish-brown, neither 
distinctly vertically striate nor papillose, 80-100 » wide at the base and 400 u high, divided 
more than one half down, the articulations on the inner face prominent, 25-35 » apart about 
one fourth up the teeth, on the outer face less distinct, about 12 « apart; lid with its obliquely 
subulate beak about the length of the rest of capsule: calyptra 4 mm. long, smooth through- 
out: spores rough, 20-24 uw in diameter. 
Type collected on the Klondike River near the mouth of Bonanza Creek, 3 miles from Dawson, 
Yukon, July 23, 1899, R. S. Williams 539 (herb. N. Y. Bot. Garden). 
DIstTRIBUTION: Dawson and Lake Lindeman at the Head of the Yukon (from the latter locality 
not fruiting); also I should refer to this species the sterile specimens collected by G. Comer on the 
N. W. shore of Hudson Bay that have been called D. angustum Lindb. 
According to description D. angustum has the habit of D. Bonjeani, the perichaetial leaf narrowed 
to a slender point up to 4 mm. long, peristome-teeth coarsely striate below, papillose above and 
spores 16-20uin diameter. It is credited to Scoresby Sound (Paris, Index Bryol. ed. 2. 2: 35), but 
up to the present time it may be considered of doubtful occurrence in this country. : 
23. Dicranum elongatum Schleich.; Schwaegr. Suppl. 1: 171. 1811. 
Dicranum subflagellare Card, & Thér. Proc. Wash. Acad. Sci. 4: 298. 1902. 
Dioicous: male plants mingled with the fertile tufts, slender, elongate, with usually 2 or 3 
scattered flowers containing 3-5 antheridia and rather numerous paraphyses: fertile plants in 
compact, broad mats up to 15 cm. high, with slender stems tomentose to near the apex: stem- 
leaves more or less erect-appressed or incurved when dry, the upper rarely somewhat curved- 
secund, 3-4 mm. long, from a lanceolate base gradually narrowed to a subtubulose, acute point, 
entire above or serrulate on the margin and slightly rough on the back; costa a little above the 
base about one fourth the width of the leaf, percurrent or excurrent, in cross-section near the 
