ee, 
| 
1897 | NORTH AMERICAN SPECIES OF AMBLYSTEGIUM 267 
matous above, commonly regular, occasionally irregular, usually 
the one or two basal rows of cells somewhat larger than those 
above, 10 to 18 wide by 25 to 4op long, alar cells above these 
short oblong, quadrate or occasionally slightly transversely 
elongated, 10 to 15m wide by 8.5 to 17m long, in the costal 
region usually short rectangular, in the middle and apical 
regions cells hexagonal or the marginal row frequently short 
rhomboidal, middle leaf cells 9.54 wide by 35 long, varying 
in width from 8 to 13#andin length from 25 to 48, apical 
cells 10.3 wide by 34m long, ranging from g to 12 wide and 
from 25 to 44m long; outer perichetial leaves triangular ovate, 
inner oblong, abruptly short acuminate, all strongly costate, 
costa excurrent, strict, or the outer spreading, serrulate or entire 
in the upper lamina. 
Sporophyte small to large, 1 to 4™ long: seta reddish at base, 
pale yellow above, or dark throughout, stout, 165 to 265m in diam- 
eter ; cortex of two to three layers of cells 6.4 to 14 in diameter ; 
central strand well differentiated, 20 to 36m of eighteen to twenty- 
five rows of cells, cells of ground tissue 13 to 21.5 in diameter; 
Capsule 1.5 to 6™™ long, cylindric, asymmetric, upright to hori- 
zontal, almost straight to strongly arcuate, more or less con- 
tracted under the mouth when dry, pale yellowish green at 
maturity, becoming chestnut brown with age; cells of exothecium 
parenchymatous on the concave side, 32# wide by 51.4 long, 
varying in width from 15 to 47H and in length from 30 to gop, 
Prosenchymatous on the convex side, 27m wide by 704 long, 
ranging from 13 to 42m wide and from 35 to 120» long, cell 
walls 3 to 5m thick, two to six rows of cells under the peri- 
Stome hexagonal isodiametric or transversely elongated, 18 to 
35 in diameter ; stomata fifteen to thirty to the capsule, scat- 
tered, 32m wide by 43 long; collum variable, one fourth to 
one half the length of the sporangium ; teeth of peristome 
cinnamon brown or yellow, paler above, lanceoate, acuminate, 
Serrulate, margined, margin broadest in the middle region, trans- 
versely striate on the back in the lower three fifths, sparsely 
Papillose above ; endostome pale, finely and densely papillose 
