DICRANACE^.] 125 [Didymodon. 



cyathiform and black when old ; calyp. reaching middle of capsule ; ' 

 lid orange, depressed, with an oblique subulate beak ; teeth of per. erect, 

 lanceolate, entire or perforated here and there, or cleft at apex, purple, 

 smooth. 



Male pi. shorter, infl. terminal, gemmae, with ovate acuminate 

 bracts. 



HAB. Crevices of alpine rocks, and among stones by mountain rills ; 



frequent. Fr. 7. 



In exposed places the plants become dwarfed, and the seta so short as 

 scarcely to elevate the capsule above the leaves ; tall plants are generally 

 decumbent and denuded of leaves at the base. 



10. DIDYMODON (HEDW.) WEB. MOHR. 



(Bot. Tasch. 1807.) 



Plants slender, csespitose, dichotomous, interwoven with radicular 

 tomentum ; leaves secund, lanceolate setaceous, with a broad nerve ; 

 angular cells dilated. Caps, straight oblong or cylindric, on a cygneo- 

 flexuose seta ; calyp. cucullate, entire at base ; per. arising below mouth 

 of caps, of 16 teeth, cleft to base into two nearly equal, linear-subulate 

 legs, remotely articulate, erect, connivent when moist. Deriv. gi%u>s 

 twin, oSovs a tooth. 



The genus Didymodon was established by Hedwig in 1792 for D. rigidulus, 

 to which in 1801 he added D. homomallus ; the former is now referred to 

 Barbtila, the latter to Ditrichum. In 1807 Weber and Mohr placed under it 

 the two species of Swartzia, Ditrichum pusillum and glaucescens and a new species 

 longirostmm which Bridel had a year previously named Dicramcm denudatum. 

 It is clear this last remains the type of the genus, and cannot be set aside for 

 the modern Dicmnodontium, than which it is also far more appropriate, for the 

 teeth are not like those of Dicmnum, and by the peristome alone can it stand 

 separate from the latter genus. Closely allied is the Mexican Atvactylocavpns 

 MITT, of which a third species is the Metzlevia alpina SCHIMP. found in Switzer- 

 land and Austria. 



DIDYMODON DENUDATITS (Brid.) Lindb. 



Dioicous ; leaves from an oblong base longly subulate, slightly 

 denticulate above, with hyaline angular cells. Caps, on a cygneous 

 seta, subcylindric, lid with a long straight beak. (T. XVII, G.) 



SYN. Dicrannm flcxuosum BRID. Muse. rec. II, P. I, 163 (1798). ROEHL. Moosg. deutsch. 329 



(1800). 

 Dicranum denudatum BRID. Sp. muse. I, 184 (1806) ; Mant. 61 (1819). C. MUELL. Synops. 



i, 403 (1849). JENS. Bry. dan. 95 (1856). 

 Didymodon longirostmtn WEB. MOHR Bot. Tasch. 155 et 463 (1807). ROEHL. Deutsch. fl. 



iii, 56 (1813). FICIN. Fl. dresd. ii, 43 (1823). BRID. Bry. ur.iv. i, 512 (1826). DUBY 



Bot. gall, ii, 567 (1830). HUEBEN. Muse. germ. 279 (1833). DE NOT. Syll. muse. 196 



(1838). 

 Cynodontium long. SCHWAEGR. Suppl. I, I, in, t. 29 (1811). MART. Fl. cr. erl. 94 (1817). 



