278 American Midland Naturalist Monograph No. 6 



This is a common and quite variable spwcies now known from numerous localities in 

 13 counties and probably occurring in all. Specimen figured: Falls Creek, Jefferson Co., 

 July 18, 1904. O.E.J. 



Other mosses closely related to P. denticulatum are P. Ruthei Limpricht, 

 with asymmetric leaves each clasping the base of the leaf above something like 

 Fissidens, and occurring in swamps from New England to Georgia and Mary- 

 land, and Minnesota. Also P. laetum Bryologia Europaea, with slenderly 

 acuminate leaves, scarcely decurrent, and with capsules almost erect and sym- 

 metric; no cilia. This species occurs from eastern Pennsylvania to Canada in 

 rock crevices in mountain areas. 



22. Pterygynandrum Hedwig 



Dioicous; slender to quite robust, variously cespitose, green to yellowish- 

 green, dull or lustrous, primary stem stolon-like, irregularly radiculose; second- 

 ary stems secund, filiform-julaceous, the base stolon-like, radiculose, often 

 flagelliform, densely-leaved, ascending, forked, bushy or pinnately branched; 

 leaves imbricate, sometimes secund, somewhat decurrent, non-plicate, deeply 

 concave, short-acuminate to somewhat obtuse, margins narrowly revolute to the 

 middle or above, entire or serrulate upwards; costa usually very short and thin, 

 forked or double, rarely single and reaching to the middle of the leaf; cells 

 narrow linear-vermicular to rhombic-hexagonal, strongly and sharply dorsally 

 papillose, the median about 3-5:1, basal cells wider and longer, alar quadrate 

 in several series; inner perichaetial leaves thin, broadly lanceolate, sheathing, 

 acute, the margins entire and plane: seta 8-15 mm long, red or yellow-red, 

 drying twisted; capsule erect, mostly symmetric, cylindric, yellow to brown; 

 annulus 2-seriate, narrow; peristome inserted near the mouth; teeth lanceolate, 

 confluent at the base, yellowish, below transversely and obliquely striate, above 

 smooth, distantly articulate, non-trabeculate; inner {peristome hyaline, smooth, 

 with quite low basal m.embrane, the segments very narrow, short, or sometimes 

 almost as long as the teeth; cilia none; spores .010-.018 mm; lid conic, shortly 

 and mostly bluntly rostrate. 



Three species; only the following in North America: 



1. Pterygynandrum filiforme [Timm] Hedwig 



(Leskea cylindrica Bridel) 



On base-s of trees and on rocks, in woods, widely distributed in the North- 

 ern Hemisphere, — in North America, extending from Greenland to British 

 Columbia and southwards to the northern United States. Occurs in the 

 Pocono region of eastern Pennsylvania and, possibly, will be found in the 

 northern or northeastern part of our region. 



Family 32. Fabroniaceae 



Autoicous or dioicous: slender to very slender, weak, cespitose, mostly 

 bright or light green, mostly lustrous: stem without central strand, weak, 

 creeping, thin, with red, fasciculate radicles; the secondary stems densely- 

 leaved, simple or branched, erect; leaves 5-8-seriate, drying appressed, spread- 



