PYLAISIA. 391 



acumen of almost equal length, entire, slightly concave, not 

 plicate ; margin plane ; nerveless or with a faint and short single 

 or double nerve ; cells linear-rhomboid, thin-walled, 6-10 times 

 as long as broad, at basal angles quadrate, pellucid, often orange, 

 rather wide and distinct. Setae numerous, slender, about f-inch 

 high ; capsule oblong, small, narrow ; lid conical, acute, short. 

 Processes of inner peristome longer than the outer teeth. 



Hab. Trunks of trees, not common. Fr. autumn and winter. 



Very closely resembling in habit slender forms of Pleuropus sericens and also 

 Hypnum cupressiforme var. resupinatum ; the long nerve of the former at once 

 separates that species, and the latter is known by the longer, shortly rostrate lid, the 

 capsule larger and slightly curved, the cilia well developed, the dioicous inflorescence, 

 the areolation usually narrower, linear-vermicular, and the basal angular cells forming 

 rather more defined auricles. Our species is usually found abundantly fruiting. 



105. 0RTHOTHE0IUM B. & S. 



Rupestral plants ; stems prostrate, irregularly branched. 

 Leaves glossy, nerveless ; areolation long, linear, without distinct 

 basal angular cells. Seta smooth. Capsule erect or very slightly 

 inclined ; cilia rudimentary. Dioicous. 



The species of this genus are distinguished from Pylaisia by 

 the absence of distinct angular cells, the dioicous inflorescence 

 and the rupestral habitat ; from Pleuropus by the absence of 

 nerve. 



/Small; leaves sub-secund, scarcely striate 2. ijitrzcatum 



\ Larger ; leaves imbricate, strongly plicate 1. rufescens 



1. Orthothecium rufescens B. & S. (Hypnum rufescens 

 Dicks.; Stereodon rufescens Mitt.) (Tab. LI. J.). 



Secondary stems crowded, erect or ascending, robust, little 

 branched, forming large, densely crowded tufts, 1-3 inches high, 

 of a vinous pink or reddish green. Leaves crowded, erecto- 

 patent, hardly altered when dry, not erect nor appressed, so that 

 the branches are obtuse, not cuspidate ; scariose, plicate, 

 triangular-lanceolate, gradually narrowed from the base, tapering 

 to a long, narrow acumen, large, i-i£ lines long, entire, margin 

 recurved for the greater part of its length ; nerveless, or very 

 faintly nerved ; cells very narrow, linear, the walls incrassate and 

 somewhat porose, uniform to the base, a very few along the line 

 of insertion slightly looser, often reddish. Seta about one inch 

 long, red ; capsule oval-oblong ; lid rostellate ; peristome pale 

 yellow. 



