226 TORTULACE^. 



worn away by the water so that only the stiff bristly nerves are 

 left clothing the stem. Leaves long, more or less spirally 

 twisted when dry and occasionally slightly so when moist, flexuose, 

 often slightly secund, narrowly oblong-lanceolate, decurrent, i% 

 to nearly 2 lines in length, more tapering than in the two previous 

 species, obtuse or shortly acute, but not acuminate, more or less 

 apiculate with the excurrent nerve; margin plane, strongly 

 thickened to apex ; cells small, rounded-hexagonal, usually 

 incrassate ; small and rectangular, not much enlarged at the base. 

 Upper cells faintly papillose. Fruit terminal on short lateral 

 branches, immersed in the long, tapering, often secund perichaetial 

 bracts or slightly emergent, seta very short ; capsule ovate-oblong, 

 bright reddish brown; lid acutely conical-rostrate, curved, red 

 peristome purple-red, twisted, long ; the teeth filiform, branching 

 above into two or three divisions, spirally twisted round the long, 

 exserted, persistent columella. 



Hab. Rocks and occasionally wood in streams, where frequently submerged ; 

 frequent ; especially common on stones in mountainous rivers. Fr. summer, but 

 variable. 



A very distinct, though somewhat variable plant, readily known by its dark 

 colour with long, twisting leaves, and when fruiting, which it usually does abundantly, 

 by the reddish brown capsules with strong red lid, which alone when the fruit is 

 ripening protrudes from the perichsetium ; but after maturity the bracts become more 

 divergent, and the capsule slightly emergent, so as to be more conspicuous. Grzmmia 

 apocarpa var. rivularis and Orthotrichum rivulare both somewhat resemble it at first 

 sight, and are often found in its company ; both however are quite different when 

 more closely examined, the shorter, less flexuose leaves alone readily distinguishing 

 them. Cinclidotus riparius is, as has been mentioned when describing that species, 

 very close to it in its growth and leaf structure, but the cells are quite smooth, the 

 leaves shorter, and the fruit quite distinct. 



When growing on the banks of lowland streams the black colour is more 

 frequently wanting, the plant is more robust, with wider leaves of a dull green, less 

 frequently secund. 



C. aquaticus, a continental species, closely resembles the present, but has longer 

 narrower more decidedly falcato-secund leaves with a thicker nerve, and the capsule 

 exserted on a seta almost equal in length to the perichsetial bracts. It has been 

 recorded from a single locality in Ireland, but according to Dr. Braithwaite there is 

 some doubt as to the accuracy of the record. 



Order X. ENCALYPTACE^. 



Erect, terrestrial or rupestral plants, usually casspitose. 

 Leaves linear, Ungulate or spathulate ; lower areolation thin, 

 hyaline, fragile, the upper small, opaque with chlorophyll and 

 strong verruculose papillae. Calyptra large, enclosing the whole 

 capsule, campanulate or cucullate, smooth or plicate. Peristome 

 double, single, or none. 



