Jennings: Manual of Mosses— 31. Hypnaceae 259 



brane about two-fifths as high as teeth; spores about .014-. 018 mm, smooth, 

 moderately incrassate, cast?.neous, ripe in autumn. 



Grout, in his Moss Flora of North America, places this species, together 

 with Callkrgon cuspidatum, in Loeske's genus Calliergonella. 



Mainly over humus, etc., in moist, shaded woods, but occurring in moist 



pastures, dry open woods, and bogs as well; Europe, Asia, and from Arctic 



America to the northern United States; as far south as Virginia in the 



mountains. 



Not uncommon in the elevated plateaus and m the mountains of western Pennsyl- 

 vania. Now known from Bedford, Somerset, Fayette, Huntingdon, Cameron, Elk, Forest, 

 McKean, Warren, Washington, and Westmoreland counties. Specimen figured: On de- 

 caying log, West Branch Swamp, Bradford, McKean Co., April 5, 1895. D.A.B. 



18. Ptilium (Sullivant) DeNotaris 



Dioicous: robust, stiff, la.xly cespitose, plume-like, yellowish-green, in shade 

 bright green, lustrous; stem 5-20 cm long, ascending to erect, simple or 2-3- 

 divided, regularly and densely complanately pinnate with derse complanate 

 branches; branches horizontally spreading, circinate at the apex, of nearly equal 

 length below, rapidly becoming shorter at the apex; leaves crowded, circinate 

 to almost coiled, deeply pluri-plicate, long-lance-subulate from a broadly ovate 

 and scarcely decurrent base, plane-margined, finely serrulate above the middle; 

 costa none, or double and short; median leaf-cells very narrowly linear, ver- 

 micular-prosenchymatous, smooth, the basal shorter, wider often and porose, a 

 few alar indistinctly differentiated, quadrate to shortly rectangular: seta 3-5 

 cm long, tortuous, red, drying dextrorse above; capsule cernuous to horizontal, 

 arcuate, about 2 mm long, castaneous, cylindric, smooth; annulus narrow, 

 2-seriate; lid dome-like, shortly apiculate. 



The genus contains only 1 species, as follows: 



1. Ptilium crista-castrensis [Linnaeus] DeNotaris 



{Hypnum crista-castrensis Linnaeus; Stereodon crista-castrensis Mitten) 



Plume Moss 



Plate XLIX 



An easily recognized, rigid, robust, plume-like, bright yellowish-green 

 species: stem-leaves about 2-3 mm long; median leaf-cells about 10-20:1, 

 branch-leaves not usually reaching 2 mm in length; e.xothecial cells strongly 

 castaneous-incrassate, small and rounded in several series at the rim, below 

 becoming oblong-rectangular; peristome-teeth castaneous, large, strongly trabec- 

 ulate, lamellate, crosswise faintly and finely dorsally papillose-striolate, con- 

 fluent below; segments as long as teeth, yellowish, papillose; the basal 

 membrane about one-half as high; cilia 2-4, slender, hyaline, about as long as 

 the segments, nodose-appendiculate; spores smoothish, castaneous, medium- 

 walled, about .010-.014 mm, usually mature in early autumn. 



On woods-humus, rotten logs, and m.oist earth, in cool woods, usually in 

 mountainous regions; Europe, Asia, and from Arctic America south to t-h<» 



