DiCRANACE^.] i6o \_Dicranum. 



Nerve -J — i width of base ; cells lax rectangular and pellucid at base, the 



angular large hyaline numerous, the upper chlorophyllose, the teeth 



hyaline. Perich. bracts like the leaves, very broad at base, sheathing ; 



seta elongated yellow erect, twisting to the left when dry, capsule erect 



pale brown, cylindric-oval, contracted below the mouth, plicate when 



old, lid conic with a subulate nearly straight beak about as long as 



capsule ; teeth pale red, cleft halfway into two unequal legs. 



Male infl. gemmaceous, inner bracts suddenly shortly acuminate, 



the nerve thin or scarce evident. 



Hab. — On sandstone rocks in mountain districts ; always sterile. 



Lennox castle, Campsie and Ben Ledi (McKinlay 1861) ! ! Ben Mac Dhui (Dickie 1861) ! 

 Mains Castle, New Kilpatrick {Gait 1865) ! ! Ben Voirlich {McKinlay 1865) ! 

 Milngavie, Glasgow (Stirton 1864) ! Bach-na-gairn, Clova (Fergusson 1868). Ben 

 Hope, Sutherland {Howse 1871) ! ! Debris of rocks by Loch Avon, Braemar 

 (Hunt 187 1) ! ! 



Very unsettled opinions have been held by bryologists with respect to 

 this moss and the next, probably influenced to some extent by the fact that 

 they frequently grow together, and that D. asperulum is variable in the rough- 

 ness and direction of the leaves, so that some forms are difficult to discrimi- 

 nate, not only from D. uncinatiim, but still more from Didymodon denudatus, 

 which it closely resembles in structure. The clear definition of the species 

 by Mr. Mitten in his Musci Indias or. drawn up from fertile specimens (with 

 which the British plant is certainly identical), shows that however closely in 

 habit and leaf-structure it resembles Didym. denudatus, it cannot be congeneric, 

 for as a genus that must stand on the form of its peristomial teeth, but those 

 of D. asperulum are perfectly dicranoid. We maj' contrast the species thus : — 



D. asperulum. Dull green, stems slender scarcely tomentose, leaves dense, variously 

 flexuose, erecto-patent, uppermost slightly falcato-secund, margin of basal wing serrated, 

 subula closely serrated, scabrous at back. 



D. uncinatum. Yellow green, rather glossy, stems robust tomentose, leaves more distant, 

 all regularly falcato — or circinato — secund, margin of basal wing, entire, subula 

 distantly denticulate in upper part, smooth at back. 



Didym. denudatus. Known at once by its large basal auricles, with large lax hyaline 

 cells. 



An elaborate paper by Milde, " Ueher Dicmnodontimn," in Botan. Zeitung, 

 1870, pp. 392 and 414, is well worth consulting, although we differ from some 

 of his conclusions. 



21. DICRANTJM UNCINATUM (Harv.) C. Muell. 

 Dioicous ; tall glossy yellow-green ; leaves strongly falcato-secund, 

 from a dilated base, longly subulate, denticulate toward apex, cells at 

 base lax quadrate, with a border becoming broader upward of very 

 narrow elongated ones; caps, erect subcylindric, lid rostrate. (T. 

 XXIV, C.) 



Syn. — Thysanomitrium uncinatum Harvey in Hook. Ic. pi. rar. i, t. 22, f. 5 (1837), e' Lond. 

 Journ. Bot. ii, p. 6 (1840). 



Dicranum uncinatum C. MuELL. Synops. i, 404 (1849). Mitt, in Journ. Lin. Soc. i 

 Suppl. 21 (1859). 



