OF WESTERN PENNSYLVANIA 87 



This genus includes about 25 species of aquatic mosses 

 more or less resembling Foiitiimlis in general appearance, 

 widely distributed over the earth, — 2 species occurring in 

 eastern United States, and likely to be found in our region. 



Key to the Species. 

 a. Large much-branched plants, up to IS cm. long: seta shorter than 



the capsule. 1. O. debilis. 



a. Small little-branched plants, up to 4 cm. long: seta longer than 

 the capsule. _ 2. O. hallianus. 



1. Octodiceras debilis (Schwaegrichen) New Combination. 

 (Octodiceras julianus Bridel ; Conomitrium jnliaiinui Montague; 



Foiitinalis Juliana Savi). 



Plants up to 15 cm. long, flaccid, floating, blackish-green 

 below, much branched: leaves distant, spreading, numerous, 

 linear-lanceolate, entire, non-bordered, vaginant lamina one- 

 fourth the length of the leaf, inferior lamina not reaching base, 

 costa ending considerably below the apex ; leaf-cells irregular 

 hexagonal or more quadrate below, about .015-.020X-020— 

 .030 mm., thin-walled : seta shorter than capsule, pale, fragile 

 at base, elliptic, erect, scarcely raised above perichtetial bracts, 

 ! ymmetric ; operculum conic-rostrate and about as long as urn ; 

 peristome-teeth short, imperfect, 16, yellowish-pellucid, ir- 

 regularly cleft and perforate in upper part ; calyptra conic, 

 dark, erose at base ; spores about .020-.022 mm., mature in 

 summer. 



Almost cosmopolitan, but rather local, on stones and on 

 wood in creeks and springy swamps. It has not been collected 

 in Western Pennsylvania other than as follows : 



Huntingdon : Porter. (Porter's Catalogue.) 



2. Octodiceras hallianus (Sullivant and Lesquereux) Jaeger 



and Sauerbeck. 

 (Conoiiiitriuin hallianuin Sullivant and Lesquereux; Fissidens 



hallianus Mitten). 



Plants smaller, up to 3-4 cm. long, laxly tufted, dirty- 

 green : stems sparsely fasciculate-branching at base ; leaves re- 

 mote, narrowly linear-lanceolate, usually in 5-10 pairs, entire, 

 the sheath not reaching over one-fourth or one-third the length 

 of the upper pair of leaves, inferior lamina narrowing and 

 reaching almost to the base ; cells irregularly hexagonal, tend- 

 ing to quadrate below, about .015-.022 mm.: seta longer than 

 capsule, pale ; capsule pale, elliptic-oblong ; peristome-teeth un- 

 divided, reddish, subulate-lanceolate, articulate, inserted below 

 the mouth of urn, papillose; operculum acutely conic-rostrate 

 and about as long as urn ; calyptra cucullate, covering the en- 

 tire operculum ; spores smooth, about .018-024 mm. 



On wood and stones, in streams, swamps, etc.. New Jersey, 

 New York, Illinois, Florida, Idaho, etc. Not reported for our 



