— 99 — 



smaller, 0.2-0.3 mm. wide, 0.4-0.6 mm. long; leaf-cells quadrate-hexagonal 

 smooth or slightly papillose, 6-S wide; leaves of branchlets rudimentary, 

 scarcely costate ; sterile. On the base of trees, sometimes on stones and 

 rocks ; with the type but less common; Canad, Muse. 395. 



In nearly all specimens of this variety leaves, from either stems or 

 branches may be found sufficiently developed to show that they are identi- 

 cal with those of L. nervosa, proving conclusively that var. nigrescens is 

 only a retrograde form of this species. Moreover tufts are often made up of 

 both plants growing together, the one bearing bulbils in small heads, the 

 other a few on flagellate branchlets. While these organs are usually sessile 

 when in compact clusters, they sometimes appear on short flagellate stems, 

 thu^ constituting a transitional form between those of the type and those of 

 var. nigrescens. Such was conspicuously the case with a specimen from 

 Vermont (Dr. Grout). 



(4) Leskea Williamsi Best. 



Plants quite small, in spreading subshining tufts, pale yellow to golden 

 brown; stems slender, creeping, radiculose, pinnately branched, 2-4 cm. 

 long; central strand none: branches ascending, simple or with flagellate 

 branchlets; lower stem-leaves decolorate, roundish ovate, abruptly acumin- 

 ate, costa short, nearly obsolete: upper stem-leaves appressed when dry, 

 €re3t spreading when moist, straightor subsecund, entire or serrulate above, 

 ovate-lanceolate, acuminate, acumen about as long as the concave biplicate 

 body, 0.25-0.35 mm. wide, 0.4-0.5 mm. long; margins recurved below or 

 plane all around; costa short, thin, simple or bifid, scarcely reaching the 

 middle; branch-leaves smaller, 0.15-0.20 mm wide, 0.25-0.4 mm. long; leaf- 

 cells smooth clear: median linear-rhomboidal to fusiform, subvermicular, 

 about 6 wide, 3-5 times as long; alar quadrate to transversely oval, in 

 about 4 rows, extending well up the margins and passing to oval-oblong ; 

 dioicous: perichetial bracts oblong-lanceolate, acuminate, striate-plicate, 

 inner subv.aginant ; pedicel smooth, flexuous, about i cm. long: capsule 

 straight, erect or inclined, oblong-subcylindric, tapering at base ; urn 2 mm. 

 long. 0.7 mm. wide, brownish: teeth reddish, incurved when dry, lanceolate, 

 confluent at base, finely striate below, rugulose above, divisural line distinct, 

 ventral surface lamellose: endostomial band strongly reticulated, about one- 

 fourth the length of the teeth: segments narrow, concave keeled, hiant, 

 about as long as teeth; cilia none: annulus of two rows of pellucid cells, 

 shed with the operculum; operculum conic, straight or obliquely beaked; 

 calyptra cucuUate, reaching to the base of the capsule; spores smooth, 

 10-13 jjL wide, mature in summer. On rocks and rotten wood. (Plate 16, 

 Figs. 55-68.) 



Type Locality: Montana: type collected by Mr R. S. Williams, on 

 Tenderfoot or Belt Mountains, Sept. 9, 1891 ; now in the Herbarium of the 

 New York Botanical Garden: also collected by Mr. Williams at Columbia 

 Falls, Mont., and by Prof. Holzinger in Minnesota. 



In general appearance L. Williamsi resembles the smaller forms of Z. 

 tectorum, from which it differs, however, by its narrower, longer acumin- 

 ate, often serrate leaves, its longer median cells, its broader, strongly reti- 

 culated endostome and its striate-plicate perichetial bracts. Named in 

 honor of my friend Mr. R. S. Williams. 



(5) Leskea Williamsi filamentosa Best. 



In thin loosely spreading or somewhat intricate tufts, pale green pass- 



