498 HYPNACEAE. 



4. MITTENOTHAMNIUM Hennings, Hedwigia 41: 225. 1902. 



[MICROTHAMNIUM Mitt. Journ. Linn. Soc. 12: 21. 1869. 

 Not Naegeli, 1849.] 



Stems slender, creeping and rooting, usually branched more or less regu- 

 larly, the branches erect often regularly pinnate; leaves of two kinds, the stem- 

 leaves differing from the branch-leaves in being smaller, more broadly lanceo- 

 late and sharply pointed; vein single or double; margins flat, serrate or serru- 

 late; cells rhombic or linear, smooth or papillose at the ends; alar cells not 

 enlarged. Monoicous, seldom dioicous. Pedicel erect, exserted; capsule erect 

 or inclined, ovoid or cylindric; mouth wide, annulus usually present; lid 

 beaked; calyptra cucullate, smooth or hairy; peristome double, its segments 

 split along the keel, with 1-3 cilia; spores small. A genus of about 106 species, 

 growing on rocks and trees, mostly in tropical regions. [Named in honor of 

 William Mitten, 1819-1906, eminent British bryologist.] Type species: 

 Hypnum thelistegum C. Muell. 



1. Mittenothamnium diminutivum (Hpe.) E. G. Britton, Bryol. 17: 9. 1914. 



Hypnum diminutivum Hampe, Linnaea 20': 86. 1847. 



Plants growing in flat mats. Stems slender, branching irregularly, the 

 branches short, seldom more than 5 mm. long; leaves spreading when dry, 

 minute, up to 0.75 mm. long by 0.33 mm. broad, ovate, acuminate, minutely 

 serrulate; veins 2, short; alar cells not enlarged; upper cells linear, 8 times 

 longer than wide, sharply papillose on the back; perichaetial leaves pale, long- 

 pointed with lax smooth cells. Autoicous. Pedicel up to 15 mm. long, slender 

 and red;' capsule nodding, usually 1 mm. long; lid blunt; annulus narrow; 

 peristome double; teeth red at base, finely striate; keeled segments perforate 

 and papillose, paler at apex ; cilia 2 ; spores minute, ripe in summer. 



On stems and rotten or charred wood in coppices, New Providence, Great Ba- 

 hama and Abaco : Florida ; West Indies ; Mexico to South America. DIMINUTIVE 



MlTTEN'S-MOSS. 



5. TAXITHELIUM Spruce, Cat. 14. 1867. 



Plants in thin pale mats. Stems flattened, with appressed leaves; simple 

 or branching, more or less regularly and distantly pinnate, with short branches ; 

 leaves crowded, concave, with a narrow, somewhat auriculate base; veins short 

 and double or absent ; margins entire or serrulate ; cells long and narrow, either 

 with several small papillae or with conspicuous branching projecting ones; alar 

 cells smooth, shorter and broader, the basal often elliptic. Autoicous or 

 dioicous. Pedicel smooth, elongate; capsule horizontal, or nodding, slightly 

 curved; lid blunt; calyptra cucullate; peristome double, the teeth paler at 

 apex and lamellate on the inner surface; endostome narrow; cilia single. 

 [Named in reference to the numerous papillae on the leaves.] A genus of 99 

 species, widely distributed in tropical regions of both hemispheres. Type 

 species: Hypnum planum Brid. 



1. Taxithelium planum (Brid.) Spruce, Cat. 14. 1867. 



Hypnum planum Brid. Spec. Muse. 2: 97. 1812. 



Plants in yellowish-green thin mats in shade. Stems creeping and rooting, 

 with short branches, seldom more than 1 cm. long; leaves glossy and flattened, 

 concave and acuminate, about 0.6 mm. long by 0.4 mm. wide; base narrower 



