418 MUSCI. Hypnum. 



below the broad mouth when dry; operculum conic-rostellate ; annulus simple: 

 processes shorter than the pale yellow teeth ; ciliolae solitary, very short. Syn. ii. 

 408; Sulliv. Icon. Muse. 201, t. 123. 



On streambanks, West Humboklt Mountains, Nevada ( Watson) ; Fort Colville (LyalT) ; British 

 America, Drummond. Common in various forms from California to Alaska and across the con- 

 tinent ; also in Europe and South America. 



33. H. serpens, Linn. Densely cespitose, with simple filiform flexuose-erect 

 branches : leaves spreading, erect when dry, very small, ovate-lanceolate, narrowly 

 acuminate, entire, costate to the middle or nearly to the apex : capsule incurved- 

 cernuous, long-cylindrical, subarcuate, strongly arcuate when dry ; operculum convex- 

 conic, acute : ciliolse in pairs, equalling the reddish teeth. Hedw. Muse. Frond, 

 iv. 45, t. 18; Engl. Bot. t. 1037. H. contextum and //. spinulosum, Hedw. Spec. 

 t. 69, 72. Amblystegium serpens, Bruch & Schimp. 1. c., t. 564. 



Common in California (Bigelow), on the roots of bushes in swamps (Bolander), on the graund 

 near Crescent City {Brewer) ; mountains of Nevada ( Watson) ; and from Alaska to British 

 America, Colorado and the Atlantic States ; Europe and South America. A very variable species. 

 H. radicalc, Beauv. (Schwaegr. Suppl. t. 20. Amblystegium radicale, Bruch & Schimp. 1. c., 

 t. 565), is a more robust and rigid form, with leaves nearly twice larger and more abruptly acumi- 

 nate from a broader base. H. orthocladon, Beauv. (Sulliv. Icon. Muse:, t. 122), and H. notcro- 

 phihim, Sulliv., which have been credited to the Pacific Coast, together with various other 

 supposed species, are considered referable to this. 



- Leaves thin and shining ; areolation narrowly rhombic, rather loose at 

 base, rectangular at the angles. 



34. H. riparium, Linn. Creeping, in swampy places, or often in water with 

 the stems and branches much elongated, distantly and subpinnately branched : 

 leaves remote or somewhat crowded, usually distichously complanate, rarely sub- 

 secund, broadly ovate- or oblong-lanceolate, more or less long-acuminate, entire, costa 

 ceasing above the middle : capsule oblong-cylindric, cernuous, incurved : ciliolse 2 or 

 3, a third shorter than the processes. Hedw. Muse. Frond, iv. 7, t. 3 ; Engl. Bot. 

 t. 2060 ; Berkeley, Brit. Moss. t. 6, fig. 3. Amblystegium riparium, Bruch & Schimp. 

 1. c., t. 570. Amblystegium vacillans, Sulliv. Icon. Suppl. 96, t. 72 ; fide Austin. 



Frequent in California (Bigelow, Brewer, Bolander) ; Northeastern Nevada and Utah ( Watson) ; 

 common in the Atlantic States and ranging from Greenland to Cuba, and throughout Europe. 



4. Leaves smooth and shining, squarrose or usually falcate-secund, nerveless 

 or shortly 1 - 2-costate : areolation linear, usually flexuose or vermicular: 

 pedicels smooth : operculum convex-conic or rostellate. HYPNUM proper. 



* Stem rootless or nearly so (except in n. 37), ascending; branches subpinnate 

 with arcuate branchlets : leaves firm, falcate-secimd,fil if ormly attenuate, costate 

 beyond the middle or nearly to the apex: mostly marsh species. HARPIDIUM. 



i- Dioecious. 



35. H. aduncum, Hedw. Stem erect, 2 to 6 inches long, slender, sparingly 

 branched, and subpinnate with short simple branchlets : leaves crowded, lanceolate, 

 long-acuminate, striate, subserrulate below, the stout costa reaching nearly to the 

 apex ; areolation somewhat rectangular, broader and subquadrate in the angles : 

 capsule cernuous, incurved-oblong, at length arcuate ; annulus broad, compound ; 

 operculum convex-conic : ciliolse 2 or 3, short. Muse. Frond, iv. 62, t. 24 ; Fl. 

 Dan. t. 2563, 2621 ; Bruch & Schimp. Bryol. Ear. t. 605, and Suppl. Hypn. t. 1 ; 

 Berkeley, 1. c., t. 10, fig. 2. 



In swamps near San Francisco (Bolander) ; Virginia and Clover Mountains, Nevada ( Watson) ; 

 British America to the Atlantic States, in South America and through Europe. A very variable 

 species. 



36. H. exannulatum, Gurnb. Distinguished from the last by its more shining 

 and more hooked-secuud leaves, costate to the apex and with very narrow closer 



