—47— 



NEW AMERICAN MOSSES. 



PonLiA (Cacodon) Porosa Lindb. Fils.* 



/;;///. Torrcy Boi. Club, 27: 318- pl- -'/, 1900. 



"Dioicous: caespitose: Stems nearly 2cm. high, round in transverse 

 section. 0.25mm. in diameter; cortical cells small, incrassate, brown; inner 

 cells larger, yellow; central strand formed of very small hyaline cells; 

 rufous-tomentose below, the rhizoids slightly papillose. Leaves ovate- 

 lanceolate, acute, rigid, imbricate, green, concave, appressed when dry, not 

 glossy, and not bordered, becoming brown when old; the lower leaves 

 small, 0.6-imm. long, margins plane; the upper leaves gradually larger and 

 more crowded, margins reliexed, crenulate; nerve thick, 0.075-0. imm. broad 

 at the middle of the leaf, brownish at base and when old. vanishing be- 

 low the apex, bi-convex, 'prominent on the back ; cells small, incrassate, 

 porose, irregular: the apical cells rhomboidal, 0.02-0. 03mm. long and 

 0.005-0.009 broad; the median cells rectangular or sub-vermicular, about 

 0.05mm. long; the basal cells rectangular or(quadrate, about o.oimm broad. 

 Perichaetial leaves larger, about 2mm. long and 0.55mm. broad, from an 

 oblong base, acute, margins reliexed throughout and crenulate; nerve van- 

 ishing in apex, thick, strongly flattened at. base, the blade formed of 2-3 

 layers of cells; cells as in the other leaves: inner bracts somewhat obtuse, 

 small, 0.05-1. 4mm. long; margins plane, crenulate; cells highly porose, 

 incrassate. .Seta 1.5mm. high, red, 0.23mm. thick, geniculate towards 

 the base, very smooth, flexuose When dry. Capsule subcylindrical, erect 

 and symmetric; 2.5mm. high and imm. thick, brown, slightly constricted 

 under the mouth when dry and deoperculate; exothecial cells irregularly 

 quadrate and rectangular, walls more or less flexuose, not incrassate, 

 0.02mm. broad; stomata superficial; annulus broad, revolute. Teeth of the 

 exostome 0.33mm. high, narrowly lanceolate, very acute, pale yellow, mar- 

 gined at apex, minutely papillose, articulations about 25; endostome imper- 

 fectly developed, hyaline, very smooth; cilia none or rudimentary: segments 

 narrow, perforated, rarely equalling the teeth. Spores pellucid, green, very 

 smooth, 0.017 (o.oi5-o.oi9mm.) Operculum 0.4mm. high, from a convex base, 

 conic and obtuse. Male plants unknown. 



A very beautiful species, most closely related to Pohlia erecia Lindb. 

 (Revue Bryologique, lO: 7-8, 1883), but differs in the better developed 

 endostome, larger capsule, thicker costa, smaller, incrassate, porose 

 cells, etc." 



" Hab. North America, Washington, Mt. Rainier, 8th Sept., 1898. 

 Coll. by J. A. Allen. On moist ground, altitude about 6,500 ft. Kindly sent 

 me by Mrs. Britton." 



♦Translated for The BryoloGIST by Miss Edith A. Warner. 



