OF \VESTERX PEXXSYLVAN'IA 287 



McKean : East Branch, Teina Swamp, north of 



[Bradford, January 18, 1895. D. A. B. 



Snyder : In bog- between Shamokin Dam and Rich- 



field. July 17, 1908. O. E. J. (Figured). 



9. HVGROHYrXi'M Lindberg. 



Autoicous or dioicous : slender to robust, in rlattish or 

 cushion-like tufts, lustrous, green to yellowish-green or golden- 

 green : stem long, procumbent, with few or no rhizoids, re- 

 motely and irregularly branched ; leaves spreading to secund 

 or imbricate, concave, smooth to weakly plicate, more or less 

 decurrent, lance-ovate, and acuminate or broadly oval and 

 obtuse to rounded, sometimes almost orbicular, margins plane, 

 entire or serrate; costa mostly unequally forked, short, weak, 

 rarely simple and long ; leaf-cells to the base uniformly narrow- 

 ly linear- vermicular, mostly with obtuse ends, smooth, the 

 apical often shorter and rhombic, the basal yellow to orange, 

 the alar portions little or not excavate but with wider, quadrate 

 to rectangular, hyaline to colored cells forming a small but 

 often well-defined auricular group ; inner perich?etial leaves 

 erect, elongate, plicate, costa simple or forked, short : seta 

 long, reddish, drying flattened and twisted; capsule inclined 

 to horizontal, mostly oval to oblong, dorsally gibbous, drying 

 arcuate and mostly constricted below the mouth, annulate; 

 peristome normally hypnoid ; lid convex-conic. 



A genus of about 20 species in wet or moist places in cool 

 regions: in Xorth America about 12 species; in our region at 

 least 2 species." probably another to be expected. 



Key to the Species. 



a. Leaves falcate. 1. H. luridnm. 



a. Leaves not falcate. b. 



b. Costa ver\* short, double, or forked, or none. 



2. H. citgy riii in. 



b. Costa reaching middle of leaf. (H. ochraccuin ( Turn- 



er )Brotherus). 



1. Hygrohypnum luridum [Hedwig] Xew Combination. 

 (Hypnnui palustre Hudson: Amblystegium palnstre Lindberg, 

 Hypnum Inridinn Hedwig; Calliergon palustre Kindberg). 



Yellowish-green, or dark-green, irregularly cespitose in 

 low patches : stems denuded below, long, divided irregularly, 

 the brandies erect to ascending, often more or less hooked at 

 the tip ; leaves close, either imbricated or more or less falcate- 

 secund, always concave, the margins incurved towards the 

 summit, oval- to ovate-oblong, entire, about 1-1.5 mm. long, 

 the apex variable, either obtuse or acute or rounded and 

 apiculate : costa usually single or forked and reaching about 

 half way up the leaf, but variable ; leaf-cells rather lax, about 

 5-10:1, usually linear-rhomboid, rather opaque, somewhat 



