174 A MANUAL OF MOSSES 



lacking, erect, monopodial or dichotomous, branches not 

 whorled ; leaves mostly 8-seriate, from a mostly half-sheathing 

 base gradually or abruptly subulate-linear, serrate upwards 

 and often on the back of the costa ; lamina upwards, sometimes 

 only at the margin, two-layered ; costa strong, projecting 

 dorsally, incomplete to excurrent ; leaf-cells small, incrassate, 

 rectangular, mamillate on both sides, the basal elongate rec- 

 tangular to linear, smooth, pellucid to hyaline: seta mostly 

 1-2 cm. long, rarely very short, mostly straight ; capsule most- 

 ly inclined, somewhat arcuate, with mouth oblique, globose, no 

 collum, when dry mostly sulcate, more or less shrunken in the 

 middle and flattened on the ends ; peristome double or single, 

 rarely none, teeth not united at the apex, neither with inter- 

 lamellar thickenings; cilia mostly none; lid small, inflated to 

 short-conic. 



A cosmopolitan genus of nearly 100 species, on earth or 

 rocks in dry or moderately moist habitats; 13 species in North 

 America ; two species in our range. 



Key to the Species. 



a. Leaf-base neither sheathing nor /conspicuously scarious, margin 



revolute. 1. B. pomifonnis. 



a. Leaf-base scarious and sheathing, margin plane. 



2. B. ithyphylla. 



1. Bartramia pomiformis Linnaeus, p.p., Hedwig. 



(Plate XXIV) 



Rather densely cespitose, soft, yellowish-green : stems 

 about 1.5-3 cm. long, erect, densely reddish-brown-felted be- 

 low ; leaves about 4-6 mm. long, the lance-subulate part 

 spreading rather abruptly from a more or less erect and con- 

 cave but scarcely sheathing lance-ovate base, the margin 

 revolute in the basal half at least, serrate above, the costa 

 rather narrow and distinct, excurrent in a spinulose-serrate 

 subulation ; basal leaf-cells smooth, hyaline, often reddish- 

 brown and pellucid at insertion, elongate-rectangular, the 

 marginal shorter in a few rows, median cells rounded-quadrate, 

 incrassate, papillose : seta about 5-10 mm. long, erect or 

 curved-ascending, smooth, reddish-brown ; capsule globose, 

 about 1.5 mm. in diameter, striate, unsymmetric, reddish- 

 brown when ripe, globose to oblong or narrowly oblong, when 

 dry deeply sulcate, cernuous, occasionally strumose, often 

 somewhat arcuate ; peristome double, teeth reddish-brown, 

 narrowly triangular-lanceolate, faintly papillose, prominently 

 articulate, sub-trabeculate, divisural faint, zigzag; seg- 

 ments two-thirds as long as teeth, carinately split, the cilia 

 two or three and rudimentary, or none ; lid convex, bluntly 

 umbonate ; calyptra narrowly cucullate, about 2 mm. long; 



