184 A MANUAL OF MOSSES 



planes vertically into four solid, three-angled, elongate- 

 pyramidal teeth; columella reaching only to the level of the 

 mouth; spores .008-.015 mm., smooth; operculum conic, 

 unistratose, cleft on one side ; calyptra conic, glabrous, plicate, 

 the margin lobed. 



A very small family of 5 species, occurring on rocks, rotten 

 wood, soil, etc., in Europe, Asia, and North America. Two 

 genera ; Tetradontiuni and the following : 



1. TBTRAPHIS Hedwig. 

 {Georgia Ehrhart). 



Slender plants, more or less densely cespitose in wide soft 

 tufts, bright green to brownish, radiculose-tomentose below: 

 stems to 3 cm. long, with central strand, three-angled, 

 branched, with distant, scale-like, ecostate leaves below ; upper 

 stem-leaves abruptly larger, approximate, ovate-lanceolate, 

 acute, margins plane and entire; costa ending below, or in 

 the apex, 4— 5-stratose at base, cells incrassate, uniform; leaf- 

 cells incrassate, round-hexagonal, wider transversely, elongate 

 in the leaf-apex, rectangular at the leaf-base: seta 1-1.5 cm. 

 long, often two together; capsule erect, symmetric, greenish, 

 v^rhen empty brownish and weakly dextrorse, without stomata ; 

 calyptra enclosing the upper one-third of the urn, its ape^ 

 carinate-toothed ; gemmae lenticular, borne in a cup formed of 

 four or five broadly cordate bracts at the apex of the more 

 slender and flexuous gemmiferous stems. 



Four species, all occurring in North America, only the 

 following one in our range: 



1. Tetraphis pellucida [Linnaeus] Hedwig. 

 {Georgia pellucida Rabenhorst). 

 (Plate XXVI) 

 Loosely cespitose in wide yellowish-green tufts : stems 

 erect, about 1 cm. high, densely felted-radiculose at the base, 

 reddish below ; basal-leaves minute, upper leaves larger, tufted, 

 ovate-lanceolate, margin entire; certain stems bearing at the 

 apex gemmse-cups about 1 mm. in diameter, the surrounding 

 leaves being broadly obovate to reniform, truncate or apiculate 

 at the apex ; perichaetial leaves linear-lanceolate, up to 4.5 mm. 

 long; costa of stem leaves wide, ending below apex, in 

 perichaetial leaves often percurrent; areolation dense, rounded, 

 the cells of the perichaetial leaves irregularly elongate at base ; 

 the cups enclosing small, many-celled, lenticular gemmae: seta 

 yellowish to reddish, erect, dextrorse above, about 1-1.5 cm. 

 long; capsule cylindric-lanceolate, erect to ascending, reddish, 

 about 2-2.5 mm. long; annulus none; peristome consisting of 

 4 linear-triangular thick teeth, reddish to brownish, compris- 



