OF WESTERN PENNSYLVANIA 277 



dry and empty strongly arcuate and constricted below the 

 mouth ; below the 2-3-seriate annulus the exothecial cells small 

 and rounded-quadrate; peristome slightly inserted, teeth 

 strongly confluent at base, dorsally cross-striolate, brownish 

 below, apically hyaline and papillose; segments about as long 

 as teeth, carinately split, the three nodose cilia about as long, 

 the basal membrane about two-fifths to one-half as high as 

 teeth; spores medium-walled, minutely papillose, brownish, 

 about .016-.019 mm., mature in early summer. 



On earth and on rocks and stones in running water, usual 

 ly in non-calcareous districts ; Europe, and, in North America, 

 from Newfoundland to New Jersey and westward to the Mis- 

 sissippi. Fairly common in our region. 



Allegheny : Laschell Hollow, June 15, 1902. J. A. S. 



Beaver : Beaver Falls, May 14, 1907. O. E. J. 



McKean : Bennett, May 19, 1895, and August 8, 1897. 



D. A. B. 



Westmoreland : Shades, Blackburn, June 13, 1908. O. E. 

 J. '(Figured). 



2. Hygroamblystegium tenax (Hedwig) New Combination. 

 {H. irriguum Loeske; Hypmim irriguuin Wilson; Amblystegium 



irriguum Bryologia Europaea; Hypnuin tenax Hedwig). 

 (Plate XXXIX) 



Dark green, aquatic, cespitose : stems rigid, irregularly 

 pinnate, long, denuded at the base, usually with a few para- 

 phyllia at the nodes ; stem-leaves ovate, about 1-1.5 mm. long, 

 gradually acuminate, acute or sub-acute, narrowed at the base, 

 sub-decurrent, spreading and sub-secund, or on the longer 

 branches erect-spreading, entire to sub-serrulate, plane-mar- 

 gined ; branch-leaves narrower and tending to lance-ovate ; 

 costa thick and wide, yellowish-brown, narrowing and becom- 

 ing indistinct in the acumen but often reaching the apex ; leaf- 

 cells hexagonal-rhomboid, about 3-6:1, incrassate, often sub- 

 opaque, smaller in the apex, at the base one or two rows usual- 

 ly somewhat enlarged, rectangular, incrassate, often colored, 

 a few rows above these shorter, quadrate, but no distinct 

 auricles being formed : seta about 1.5 cm. long, smooth, castane- 

 ous, dextrorse; capsule oblong, the urn 2-2.5 mm. long, sub- 

 cernuous and sub-arcuate before ripening to strongly arcuate 

 when dry, smooth, constricted below the mouth, brownish ; 

 annulus 3-seriate ; lid convex-conic, apiculate ; peristome-teeth 

 basally confluent, orange-pellucid and dorsally cross-striolate 

 below, bordered, strongly trabeculate ; the segments slightly 

 shorter than the teeth, carinately split but scarcely gaping, 

 yellowish-hyaline, the 3 cilia nodose, hyaline-papillose, about 

 as long as the segments, the basal membrane about two-fifths 

 as high ; exothecial cells small and rounded, hexagonal to trans- 



