186 American Midland Naturalist Monograph No. 6 



dry somewhat plicate, about 1.5-2 mm long, the extreme apex rather blunt, the 

 base concave, the margins reflexed; perichaetial leaves loose in texture, the inner 

 sheathing, reaching to the base of the capsule or a little higher: seta short, 

 slightly longer than the capsule; capsule ovate-cylindric, thin-walled, rather 

 gradually narrowed below, about 3-4:1, about 1.5 mm long; exothecial cells 

 rather incrassate, irregularly polygonal to rectangular-oblong, several rows at 

 the narrowed mouth smaller, rounded-quadrate and dark-castaneous; peristome- 

 teeth whitish, lance-linear, rather remotely articulate, sometimes perforate along 

 the divisural, the inner peristome entire to more or less torn, adhering to the 

 ventral surface of the teeth; lid short-rostrate; spores mature in winter, orange- 

 incrassate, almost smooth, about .023-. 025 mm. 



In woods on trees, rarely on rocks; Asia, and from New England to On- 

 tario and the Gulf States. 



Common in eastern Pennsylvania but rare in our region. Beaver Co.: About 8 feet 

 up on elm trunk, along Raccoon Creek, one mile south of Traverse Creek. April 1, 1934. 

 Chas. M. Boardman. McKean Co.: Near Latshaw, N. Y. north of Bradford, August 

 25, 1895. D.A.B. (figured). 



Family 27. Neckeraceae 



Dioicous, rarely autoicous or synoicous; sexual clusters only on secondary 

 shoots and their branches, with filiform, often yellowish paraphyses: slender 

 to robust, mostly stiff, laxly cespitose: stem somewhat dorsiventrally flattened, 

 with oi without a rudimentary central strand: primary stem more or less creep- 

 ing, mostly filiform, mostly sparsely fasciculately radiculose; secondary stems 

 more or less elongate and ascending or much elongated and pendent, mostly 

 distantly or symmetrically pinnate, thickly-leaved, julaceous or flattened; leaves 

 nearly always pluri-seriate, uni-stratose, of various forms; costa mostly delicate, 

 homogenous, simple or double or none; median cells mostly prosenchymatous, 

 the apical sometimes parenchymatous, the basal often colored, the alar some- 

 times differentiated: capsule mostly erect and symmetric, peristome mostly 

 double, teeth yellowish to brownish, lance-linear, dorsally sometimes abnor- 

 mally thickened, ventrally trabeculate; the inner peristome with mostly low 

 carinate basal membrane, rarely rudimentary or none, segments linear to fili- 

 form, often fenestrate, rarely cleft the whole length, cilia mostly none; lid 

 conic, erectly to obliquely rostrate; calyptra mitrate to cucullate, mostly hirsute; 

 spores of varying size. 



A large family, occurring mainly on trees in warmer regions, often forming 

 a conspicuous part of the vegetation; about 20 genera, of which but three 

 occur in our region. 



Key to the Genera 



A. Secondary stems flattened, ascending or pendent; leaves mostly conspicuously unsym- 



metric B 



A. Secondary stems mostly erect and branched in a tree-lil;e manner; leaves not com- 



planately disposed 3. Porotrichum 



B. Exannulate; basal membrane of inner peristome low, cilia none, segments narrowly 



linear 1. Neckera 



B. Annulus 2-seriate; basal membrane conspicuous, cilia rudimentary and soon disap- 

 pearing or well-developed, segments about ss broad as teeth 2. Homalia 



