158 American Midland Naturalist Monograph No. 6 



walled, smooth; perichaetial leaves longer: seta long, erect, straight or genicu- 

 late in the middle; sinistrorse below, dextrorse above; capsule erect, symmetric, 

 smooth, oval or cylindric; annulus none; peristome inserted below the m^outh, 

 consisting of the entire mass of tissue enclosed within the epidermal operculum, 

 this splitting by two 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; T etradontium and the 

 following: 



1. Tetraphis 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, with 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, when empty 

 brownish and weakly dextrorse, without stomata; calyptra enclosing the upper 

 one-third of the urn, its apex 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 XXX 

 Loosely cespitose in wide yellowish-green tufts: stems erect, about 1 cm. 

 high, densely felted-radiculose at the base, reddish blow; basal-leaves minute, 

 upper leaves larger, tufted, ovate-lanceolate, margin entire; certain stems 

 bearing at the apex gemmae-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; aerolation 

 dense, rounded, the cells of the perichaetial laves irregularly elongate at base; 

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

 reddish, erect, dextrorse above, about 1-15 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, comprising 

 about one-fifth of the length of the capsule; operculum lustrous, conic, acute; 

 calyptra whitish and lacerate below, plicate, enclosing the whole capsule, at 

 apex solid, acute, rough; spores about .010 mm, thin-walled, slightly papillose, 

 mature in summer or early fall; capsules persistent. 



