Jennings: Manual of Mosses — 31. Hypnaceae 245 



acuminate acute apex, the margins incurved towards the apex; costa short, in- 

 distinct and double, or none; median leaf-cells linear, somewhat incrassate, 

 often somewhat obtuse at ends, about 8-10:1, shorter at the apex, the alar 

 abruptly much enlarged and inflated, the marginal thin-walled, the inner ones 

 incrassate, hyaline to yellowish-brown, forming well-defined and somewhat in- 

 flated auricles; perichactial leaves whitish, the outer with flexuous spreading 

 tips, the inner erect, long-acuminate, often crose-denticulate at the apex, pli- 

 cate: capsule short, oval to oblong, cemuous, turgid, yellowish-brown; peri- 

 stom.e-teeth yellowish, slender, strongly trabeculate; segments carinately cleft 

 and about equalled in length by the 2 or 3 granulose and nodose cilia; lid 

 conic-convex; annulus usually 3-seriate; spores mature in spring. 



On rocks in streams or along the banks where kept wet, in hilly or moun- 

 tainous and usually non-calcareous regions; Europe, and from Newfoundland 

 to Alaska and south to Georgia and Colorado. 



Some specimens from McKean County shew intergradations with the fol- 

 lowing variety. 



Fayette Co.: On rock in stream-bed, Cucumber Run, above Falls, Ohiopyle. June 



24, 1934; and on rock in stream, Sheepskm Run, Ohiopyle, Nov. 6, 1943. C.M.B. 



Westmoreland Co.: On rock in stream one mi. above Darlington, May 19, 1945. 

 C.M.B. 



2a. Hygrohypnum eugyrium var. Mackayi (Schimper) Brothcrus 



(Hypnum eugyrium var. Mackayi Schimper; Hygrohypnum Mackayi Loeske; 



Hypnum Mackayi Breidler) 



Plate XLV 



Leaves about 1-1.5x0.6-0.7 mm, broadly oblong, distinctly serrulate at 

 apex, sub-clasping and auriculate at base, less strongly falcate than in the 

 species; perichaetial leaves hyaline, plicate, the inner reaching 3 mm in length: 

 seta about 2 cm long, castaneous, smooth, somewhat flexuous, dextrorse above; 

 capsule with urn 2-2.5 mm long; exothccial cells rounded-hexagonal, somewhat 

 incrassate-collenchymatous, rather uniformly seriate; peristome-teeth about as 

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

 high; spores minutely papillose, rather thin-walled, faintly yellowish, about 

 .024-. 027 mm, mature in late spring or early summer 



When sterile it is very difficult to distinguish this moss from Sematophyl- 

 liivi marylandicum. In the Sematophyllum the walls of the outer alar cells 

 ?rc not much thinner than are the walls of the inner alars. Sematophyllum also 

 sometimes has a faint double costa. 



On stones in streams in hilly or mountainous regions and with about the 

 same general distribution as the sptcies. 



Rare in our region. McKean Co.: On stones in brook at head of Bennett Brook, 

 Bradford, August 26, 1894, November 2, 1896, and July, 1897 (figured), the latter 

 issued as Grout's North American Musci Pleurocarpi. No. 129. Also Limestone Creek, 

 Bradford, July 7, 1895. All D.A.B. Also Tionesta Tract, Wetmore Twp., C.M.B. 

 Sept. 23, 1939. 



