172 American Midland Naturalist Monograph No. 6 



glaucous-green above, more or less hoary, especially in late summer or in 

 autumn, owing to the colorless tips of the leaves: stems from 2 or 3 up to 8 or 

 10 cm long, rather slender, irregularly forking and branching, the branches 

 usually rather short; leaves more or less secund on the procumbent stems, 

 when dry imbricated but with recurved apex, when moist spreading, concave, 

 ovate, 1.5-3 mm long, the apex sub-obtuse to long-acuminate, papillose-denticu- 

 late to spinulosely denticulate, more or less hyaline; costa none; the median 

 basal leaf-cells yellowish pellucid, not papillose, narrowly linear, incrassate, 

 porose, towards the margin and in upper part of leaf the cells sub-quadrate or 

 rectangular, with more or less sinuose walls, the cells in the angles often brown- 

 ish and larger, the median and upper cells prominently papillose, longitudinally 

 seriate, varying from quadrate to rounded or hexagonal; perichaetial leaves 

 prominently ciliate towards the apex, not plicate: seta practically none: capsule 

 sub-sessile, immersed, globose-oblong, about 0.6-0.9 mm in diameter, wide- 

 mouthed ?nd truncate when dry and empty, red-rimmed, the urn castaneous; 

 lid convex, sometimes mamillate, about three-fourths as wide as the median 

 diameter of the urn; calyptra small, sub-cucullate and fugacious; annulus none 

 but one or two rows of exothecial cells at the rim of the urn smaller, laterally 

 elongate, and castaneous-pellucid; peristome none; spores mature in spring, 

 minute, shallowly pitted, pale, thin-walled, about .025-.028 mm: autoicous. 

 On dry rocks, boulders, stone-walls, etc., in non-calcareous habtiats; almost 

 cosmopolitan; in North America occurring from the Arctic regions to Mexico. 



Common in our region. Now known from Allegheny, Beaver, Bedford, Fayette, For- 

 est, McKean, Somerset, Washington, and Westmoreland counties. Specimen figured: Ohio 

 Pyle, Fayette Co., May 30-31, and July 4, 1908. O.E.J. Not yet known from the glaci- 

 ated region of western Pennsylvania. 



la. Hedwigia ciliaTa f. LEUCOPHAEA (Bryologia Europaea) Jones 

 (H. albicans var. leucophaea Limpricht) 



Very hoary; more robust than the species: leaves more falcate, wider, the 

 hyaline base of the piliferous acumination occupying about the whole upper 

 third of the leaf. 



With the type and in the same general habitat. 



Huntingdon Co.: Stone Creek, T. C. Porter. (Porter's Catalogue). Westmore- 

 land Co.: T. P. James. (Porter's Catalogue). 



PLEUROCARPI 



In the following families the flowers, as a general rule are borne in the 

 axils of leaves along the side of the stem. The antheridial flowers are enclosed 

 in an involucre of modified leaves, the perigonial bracts; the archegonial flow- 

 ers have a similar involucre of perichaetial bracts; and the sporophyte thus is 

 borne laterally on the stem. Most of the pleurocarpous mosses have a creep- 

 ing habit. 



Family 24. Fontinalaceae 



Dioicous or autoicous: filiform paraphyses few: slender to robust, aquatic, 

 floating, blackish-green or reddish-brown: stem without central strand, 3-5- 



