68 American Midland Naturalist Monograph No. 6 



spreading at the tip, the tubulose apex usually shorter than the broad base: 

 capsule almost symmetric, little or not at all inclined, slightly or not at all 

 strumose. 



On stumps, logs, or on the ground, Europe and in the eastern part of 

 the United States. 



Rare in our region. Huntingdon Co.: Porter. (Porter's Catalogue). Westmore- 

 land Co.: A sterile specimen! from near Bear Cave, Chestnut Ridge, Hillside. Septem- 

 ber 17, 1909. O.E.J, and G.K.J. 



Family 4. Fissidentaceae 



Autoicous or dioicous: minute to large, gregarious to cespitose, mostly 

 green: stem oval, mostly with central strand, basally radiculose, or with reddish 

 rhizoids from the leaf-axils; leaves distichous, mostly vertically placed, so that 

 they stand edgewise to the stem with a clasping sheath at the base, or extending 

 well up the leaf, and a dorsal lamina which is often somewhat decurrent, the 

 apical lamina being lacking in the perichaetial and lowest stem leaves and 

 little developed in Bryoxiphium; costa usually present; leaf-cells small, uniform, 

 rounded hexagonal, chlorophyllose: seta erect or cygneous, usually elongated; 

 capsule erect and symmetric, or cernuous and unsymmetric or curved, smooth, 

 collum present; annulus present or none; peristome present, except in Bryoxi- 

 phium, usually inserted, simple, red; teeth articulate, united at base, cleft to 

 the middle or below into two or three filiform divisions, trabeculate with two 

 serie:. of projecting transverse plates, yellowish; spores mostly small; operculum 

 more or less rostrate; calyptra small, narrowly conical, entire or cleft on one 

 side, rarely several times cleft, mostly smooth. 



A family of over 700 species, largely tropical, with widely varied habitats, 

 represented in our range by three genera. 



Key to the Genera 



A. Dorsal lamina very narrow: peristome none: stem radiculose-bulbiform at base 



1. Bryoxiphium 



A. Dorsal lamina usually broad: peristome present: stem not radiculose-bulbiform at 



base B 



B. Mostly not aquatic; sometimes submerged, but floating 2. Fissidens 



B. Aquatic, filiform, floating mosses 3. Octodiceras 



1. Bryoxiphium Mitten 



(Eustichia Bridel) 



Slender, dioicous, more or less densely silky-cespitose, bright green or yel- 

 lowish: stem stiff, oval in cross-section, with central strand, radiculose at the 

 extreme base, upwardly flattened, with distichous, closely imbricated leaves, 

 simple or irregularly branched; leaves from a linear-lanceolate base, either 

 linear, with a small acumen, or rounded and abruptly more or less long- 

 subulate, denticulate above; costa percurrent, with a very narrow dorsal wing 

 which does not extend to the base of the leaf; basal leaf-cells hyaline, rectangu- 

 lar, upper cells chlorophyllose, triangular to irregularly trapezoidal, smooth, 

 towards the margin linear and forming a distinct border; perichaetium terminal, 

 with two concave, ovate, prolonged-acuminate, serrulate leaves with a complete 



