268 BOTANICAL GAZETTE [OCTOBER 
throughout, membrane one half the length of the segments ; 
the latter lanceolate, carinate, open along the keel between the 
articulations, rarely gaping; cilia two to four, slender, equaling 
the segments, nodose to imperfectly appendiculate ; operculum 
obliquely apiculate from a high convex or conic base, usually as 
broad as the capsule; annulus of two to three rows of cells: 
spores light brown, minutely papillose, 13 to 21m in diameter: 
calyptra equaling the capsule or shorter, split half its length. 
Hab.: On the ground, on decaying wood, at the bases of 
trees or occasionally on rocks, in moist or wet shady places. 
Type locality Lancaster, Pennsylvania. 
Europe, North and tropical America: throughout southern 
Canada and the United States. Very common and widely dis- 
tributed. 
With the exception of A. rifarium, the most variable of all species found 
in America; the smaller forms easily confused with A. serfens, while occa- 
sionally the more robust forms approach very nearly to 4. £ochdd in the habit 
of growth and shape of leaf. Here as with A. serfens, while there is wide 
variation there are no forms of sufficient constancy to entitle them to varietal 
rank. The large form with erect straight branches commonly known as A. 
orthocladon perhaps is the most constant of all the forms, but I have not been 
able to call it anything more than a form. 
AMBLYSTEGIUM IRRIGUUM (Wils.) Bruch & Schimp. P/ate XII. 
fe. 1. ; 
Synon.: Hypnum fluviatile. Many authors prior to 1854. Not of Swartz. 
Hypnum irriguum Wilson, Bryolog. Brit. 361. p/. 25. 1855.— Berkeley, 
Handb. Brit. Moss. 97. 1863.— Hobkirk, Syn. 164. 1873.— Boulay, Musc. Fr 
72. 1884.— Lesquereux & James, Man. Moss. N. Amer. 374. 1884. 
Amblystegium trriguum Bruch & Schimper, Bry. Eur. Ambly. I! (under 
the name A. fluviatile, pl. 5. 1853.—Schimper, Syn. Musc. Eur. (1st ed.) 
594. 1860. (2d ed.) 712. 1876. — Milde, Bry. Siles. 326. 1869.— De Notaris, 
Epil. Bry. Ital. 152. 1869.—Hartmann, Skand. FI. (10th ed.) 20. 1871. 
— Lindberg, Musc. Scand. 32. 1879.— Hobkirk, Syn. (2nd ed.) 213- 1884.— 
Macoun and Kindberg, Cat. Can. Pl. 6:220. 1892.— Husnot, Muse. Gall. 
360. £2. 1037. 1894.— Dixon & Jameson, Stud. Handb. 444. AZ 56. 1896. — 
Braithwaite, Brit. Moss Fl. 3:21. A/. 88. 1896. 
Amblystegium fluviatile var. irriguum R. du Buysson, Ess. Anal. gen- 
Ambly. 1883 
