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1897] NORTH AMERICAN SPECIES OF AMBLYSTEGIUM 253 
numerous, short, 0.5 to 1° long, erect: leaves not crowded, 
lanceolate from an ovate base, sometimes linear-lanceolate, long 
acuminate, acumen very slender, 130 4 wide by 440 p long, rang- 
ing in width from 100 to 150 and in length from 250 to 500m, 
reaching greatest width in basal fifth, but some distance above 
the line of insertion, straight or more or less falcate, equally 
spreading, suberect or subsecund, appressed when dry except 
the slender points, entire, with only a trace of costa in basal fifth, this 
sometimes double or branching or very rarely wanting ; leaf cells 
parenchymatous at base and along margins in lower half, else- 
where prosenchymatous, cells at basal angles regular, quadrate or 
slightly transversely elongated, becoming short rectangular toward the 
middle, 11 m wide by 9.5 m long, varying in width from 8.5 to 164, 
and in length from 6.5 to 15, cells in the middle of the lower 
third oblong, about 1:1.5, those of the middle region irregularly 
hexagonal, occasionally slightly flexuose, 8.2 » wide by 26 long: 
ranging in width from 6.5 to 10 # and in length from Ig to 324, 
cells in apical region much as in median region, but regularly 
somewhat longer, the terminal cell in most cases being the longest 
in the leaf blade, varying in width from 6.5 to 9.5 # and in length 
from 15 to 44, averaging 8 w wide by 30.5 # long; outer peri- 
chetial leaves abruptly long acuminate from a broadly ovate 
base, acumen equaling the body, ecostate or with a trace of 
costa at base, inner leaves much larger, linear lanceolate, 
abruptly acuminate, acumen one-half the length of the body, 
costate to middle or beyond, costa thin but distinct, all entire. 
Sporophyte small, 1°" long, cinnamon brown: seta flexuous 
iN upper third, 120 to 150 mw in diameter, central strand 16 to I9 4 
in diameter, composed of ten to eighteen rows of cells, cortex of 
two or three layers of cells, with walls moderately thickened, 
6.5 to 13 w in diameter, cells of ground tissue 13 to 21.5¢ in 
diameter, largest near the central strand : capsule oblong cylin- 
drical, 1 to 1.5™" long including operculum, symmetric or mod- 
frately incurved, erect, becoming more or less inclined by the 
bending of the seta, only slightly contracted under the mouth 
in drying, collum shrivelling and becoming wrinkled, wall of 
