338 A MANUAL OF MOSSES 



1-1.3 mm. long-; exothecial cells small and rounded at the rim, 

 below larger and oblong to linear-oblong, all sharply yellowish- 

 iiicfassate : annulus indistinct ; peristome-teeth confluent at 

 base, castaneous and dorsally cross-striolate below, closely 

 trabeculate and lamellate, margined, hyaline towards apex ; 

 segments very slender, about as long as teeth, carinately cleft 

 and gaping in median portion, yellowish, papillose, basal 

 membrane one-fourth to one-third as high, the cilia somewhat 

 shorter than the segments, filiform, nodose, hyaline-papillose; 

 spores rather incrasste, smoothish, brown-walled, .013-.016 

 mm. According to Grout this is probably B. salcbrosum 

 variety densum Bryologia Europ^ea. In most characters it is 

 quite similar to typical salcbrosum but differs in having narrow 

 leaves with evenly narrowed and very slender acuminations. 



Ranging from New England and the Adirondacks to Ten- 

 nessee, and occurring also in British Columbia. Rare in our 

 region. 



Allegheny : Guyasuta Hollow on clay and stones, Oc- 

 tober 12, 1908. O. E. J. 



McKean : Bennett Brook. May 3, 1893. D. A. B. 



(Figured). 



7. Brachythecium acutum (Mitten) Sullivant. 



(Hypnitm acntum Mitten). 



Loosely cespitose, bright glossy green : stems long, flexu- 

 ous. creeping, basally radiculose, sparsely branched ; branch- 

 lets short, sometimes reflexed ; leaves loose, open-spreading, 

 more imbricate when dry, lanceolate to lance-ovate, non-striate, 

 slightly decurrent, plane-margined, scarcely concave, obscurely 

 serrulate or almost entire, short auriculate at base, the mar- 

 gins tapering gradually and almost in a straight line from 

 base to apex; median leaf-cells linear-vermicular, about 10:1, 

 the basal lax, the alar sub-quadrate, small, numerous and ex- 

 tending down to form a rather strong decurrent portion ; costa 

 reaching to somewhat above the middle ; stem-leaves wider, 

 triangular-ovate, reaching 2.5x1 mm., long and slenderly 

 acuminate: seta smooth, about 1.5-2.5 cm., long, flexuous ; 

 capsule ovoid-oblong, dorsally turgid, inclined to horizontal, 

 usually slightly arcuate, about 2-3:1; annulus narrow; peris- 

 tome hypnoid, the cijia 2 or 3, strongly nodose to sub-ap- 

 pendiculate ; lid conic-acuminate ; spores mature in late fall or 

 winter. 



In moist woods on rotten logs and earth : Canada and the 

 northern United States, south to Arkansas. Rare in our 



region. 



McKean : D. A. B. (Porter's Catalogue). 



