OF WESTERN PENNSYLVANIA 241 



leaves loosely imbricate, open-erect, wide-ovate, narrowly 

 long-acuminate, spinulose-dentate all around, very shortly 

 costate or ecostate ; leaf-cells large, pellucid, elliptic-rhomboid, 

 dorsally with large papillae as in Thelia asprella; perichsetial 

 leaves sheathing, lanceolate, filiform-acuminate, dentate: cap- 

 sules sub-erect, small, inflated, oval-oblong to obovate-oblong ; 

 seta long ; peristome normally hypnoid, with articulate, yellow- 

 ish, transversely-striate teeth, entire segments and cilia two, 

 somewhat shorter than the teeth. 



Mainly in crevices and hollows in limestone rocks in hilly 

 or mountainous regions ; Europe, Asia, and from Nova Scotia 

 to Minnesota and North Carolina. Rare in our region. 



Huntingdon : Alexandria. T. C. Porter. (Porter's 

 Catalogue). 



3. HAPLOHYMENWM Dozy and Molkenboer. 



Dioicous : slender, stiff, forming mats, dull, dark green to 

 yellowish- or brownish-green : stems filiform, creeping, widely 

 radiculose, here and there in fascicles, more or less pinnately 

 branched, branches spreading, short, obtuse ; paraphyllia none ; 

 lower leaves smaller, somewhat secund, abruptly lance-subu- 

 late and recurved-circinate from a broadly ovate base ; costa 

 very short or none; upper leaves spreading to squarrose- 

 spreading, imbricate when dry, from a concave ovate base 

 more or less abruptly Ungulate, obtuse to short-acute, non- 

 plicate, margin plane and entire; costa delicate and reaching 

 to mid-leaf, or stronger but not reaching apex; median leaf- 

 cells turgid, thin-walled, rounded-hexagonal, with mostly sev- 

 eral papillae over the lumen, the marginal smaller, transversely 

 broader, in many rows towards the basal margin transversely 

 rectangular or hexagonal, only in middle of base oblong and 

 pellucid : seta 2-4 mm., thin, drying twisted, reddish or yel- 

 lowish, smooth ; capsule erect, oval, smooth, brownish, broadly 

 annulate; peristome-teeth basally confluent, lance-linear, yel- 

 lowish, distantly articulate, split apart above, the ventral layer 

 broader, hyaline, non-trabeculate, but with papillae-like irregu- 

 lar processes; inner peristome smooth, the l3asal membrane 

 very low, with no segments nor cilia; lid conic, obliquely 

 short-rostrate; calyptra inflated-cucullate, furnished with a 

 few long, erect hairs ; spores .020-.02S mm., papillose. 



About a dozen species, mostly living on tree-trunks, rarely 

 on rocks ; one species occurring in North America and reaching 

 our region. 



1. Haplohymenium triste (Cesati) Kindberg. 



(Leskea tristis Cesati; Anonwdon tristis Sullivant). 



(Plate XXXIV) 



Small, very slender, dull dirty-green, loosely, thinly, and 

 intricately cespitose: stems prostrate, sometimes pendent, 



