t 
1897 | NORTH AMERICAN SPECIES OF AMBL YSTEGIUM 255 
ExsiccaTl: Ayfnum adnatum Sulliv. & Lesq., Musc. Bor. Amer. (Ist 
ed.) 344. (2d ed.) 521, 522.— Macoun, Can. Musc. 322, 323 (Herb. Wis.). 
Amblystegium adnatum Austin, Musc. App. 370. 1870. 
TYPE in Herb. Hedwig. 
Gametophyte bisexual, depressed, in wide thin mats, yellowish, 
pale green or sometimes dark green, closely adhering to the 
substratum : stems irregularly branching, creeping, 2 to 4 long, 
slightly flattened, the two diameters usually 4:5, 140 by 1754 
in diameter, ranging from 100 by 125 ¢ to 180 by 225; cen- 
tral strand none; cortex of three or four layers of cells, 6.5 to 
14 in diameter; cells of ground tissue 10 to 22.5m, largest 
near the center, cell walls noticeably thickened ; branches 
numerous, very short, 2 to 5™", erect: leaves crowded, erect 
spreading, ovate or oblong, abruptly short acuminate, acumen broad, 
concave, entire or occasionally irregularly denticulate, usually 
with a thin simple branched or double costa in basal Jifth, 345 » wide 
by 820 long, varying in width from 300 to 3804 and in length 
from 800 » to more than a millimeter; leaf cells in all but alar 
regions prosenchymatous, cells of basal angles regular, quadrate, 
slightly transversely elongated or occasionally oblong, 13.9# wide 
by 9.2 long, varying from 12 to 17 min width and from 6.4 to 
15 # in length, toward the middle of the base changing abruptly to 
long hexagonal, almost vermicular, walls thin, usually thicker 
and firmer in the middle region, cells varying in width from 
4-3 to 8.6 and in length from 28 to 58 », averaging 6.5 u wide 
by 42.8 long, toward apical region gradually changing from hex- 
agonal to rhomboidal, 8.8 » wide by 24.6m long, ranging in width 
from 6.9 to 10.6@ and in length from 17 to 32, longest cells in 
the middle of the leaf ; in general the leaf cells very regular in all 
parts, the alar quadrate cells sometimes extending as much 
as one third the length of the leaf; outer pericheetial leaves 
broadly ovate, gradually acuminate, acumen half the length of 
= body, spreading, inner leaves ovate to oblong abruptly 
acuminate, acumen short, one fifth to one fourth the length of 
the body of the leaf, strict, all irregularly denticulate to dentate 
above the middle and costate to the middle, costa evident, 
