234 American Midland Naturalist Monograph No. 6 



cordate-triangular, finely and gradually acuminate, varying from erect-spread- 

 ing to sub-secund; branch-leaves rather narrower, more usually strongly falcate- 

 secund; all leaves rigid, altered but little in drying, not plicate, markedly decur- 

 rent, the base cordate and narrowed, the margin plane or recurved at the base 

 and closely and finely serrulate from base to apex; costa strong, usually ending 

 in the apex; median leaf-cells elliptic-hexagonal to elongate rectangular, mostly 

 about 3-6:1, usually obtuse at the ends, the alar abruptly inflated, hyaline or 

 colored, forming well-defined auricles of sub-rectangular cells, these cells reach- 

 ing to the base of the costa or nearly so; perichaetial leaves erect, strongly 

 costate but scarcely plicate, denticulate: seta long, reddish, flexuous, up to 3-5 

 cm long, flattened and twisted; capsule reddish, sub-cylindric, rather turgid, 

 arcuate, when dry and empty constricted below the mouth and more or less 

 sulcate; lid conic, acute, or apiculate; peristome hypnoid, the segments more or 

 less cleft cn.inatcly, cilia 2 or 3, nearly as long as the segments and teeth; 

 annulus simple, narrow; spores mature in spring. 



On earth, stones, etc., in or near springs, streams, or swamps, principally in 

 calcareous districts; Europe, Asia, northern Africa, and, in North America, 

 from the Arctic regions south to the southern part of the United States. 



Rare in our region. Huntingdon Co.: Spruce Creek. T. C. Porter. (Porter's Cat- 

 alogue). 



5. Hygroamblystegium noterophilum (Sullivant) Warnstorf 



(Hypntim noterophilum Sullivant; Amblystegium noterophilum Holzinger; 

 Hypnum irriguum spinifoliiim Lesquereux and James) 



Larger than fluviatile, dull dark green in older parts, rather stiff, irregularly 

 branching; stem with strong central strand and thick-walled cortical cells; leaves 

 entire, lance-oblong when aquatic, when emersed ovate and up to 2.5 mm long; 

 basal and costal part of leaf bi-stratose; capsule highly stomatiferous; spores 

 mature in early summer. 



In springs and running water in calcareous regions. Ontario and northern 

 United States, the type locality in Franklin County, Pennsylvania. 



7. SCIAROMIUM Mitten 



Mostly dioicous: more or less robust, stiff, cespitose, dull, dark green 

 to blackish: stem long, floating, sparsely radiculose, with irregularly and 

 sometimes rather fasciculately arranged branches mostly directed forwards 

 and mostly long and simple; leaves close, spreading to secund, concave- 

 carinate, non-plicate, not at all or but slightly decurrent, ovate to lance- 

 oblong, sub-acute to acuminate, plane-margined, mostly entire, broadly and 

 thickly bordered; costa strong, ending apically in the border or excurrent; 

 median leaf-cells chlorophyllose, strongly incrassate, rather opaque, prosen- 

 chymatous-hexagonal, 2-4 (-6) :1, the basal cells more lax, the alar somewhat 

 differentiated, the marginal slender, strongly incrassate, hyaline, in several 

 layers; costa ending in the border at the apex: seta 1-3 cm long, castaneous 

 below, more yellowish above; capsue inclined, unsymmetric, oblong, when dry 

 somewhat constricted below the mouth, annulate; peristome-teeth yellow, bor- 



