214 TORTULACE/E. 



is a distinct approach to a spiral twisting of the peristome ; and I 

 think it will be generally conceded that these considerations, 

 together with the great undesirability of founding new genera on 

 old material, form sufficient justification for widening the defini- 

 tion of the genus to even this extent. The greater or less 

 twisting of the peristome is only a question of degree ; and its 

 inadequacy as a generic character is obvious when it leads for 

 instance to the separation of species so closely allied as T. 

 nitidum and T. tortuosum. 



/Basal hyaline cells ascending up margin of leaf 2 



\ Basal hyaline cells not higher at margin than at centre 6 



{Leaves wide, soft, obtuse, more or less cucullate at apex .3. jlavovirens 

 Leaves narrower, not cucullate, more or less acute 3 



/Leaves rather rigid, straight, mostly broken across 4 



^\Leaves flexuose, less fragile 5 



{Leaves short with shortish points, strongly curled when dry 7. nitidum 

 Leaves with long narrow points, not or hardly curled when dry 9. fragile 



/Leaves over two lines long, with very long, tapering points 8. tortuosum 



5\Leaves rarely two lines long, with short points 6. incline/turn 



.-/Nerve excurrent in a cusp or mucro 7 



\Nerve ceasing in apex 8 



/Leaf-margin recurved at apex, more or less cucullate 1. crispulum 



'\Leaf-margin flat or nearly so at apex 2. mutabile 



o/Leaves crenulate-notched at margin, scarcely dilated at base 4. tenuirostre 



\ Leaves entire at margin, with dilated base J. hibernicum 



1 . Trichostomum crispulum Bruch. (Mollia crispula Lindb., 

 Braithw. Br. M. Fl.) (Tab. XXXI. H.). 



Densely tufted, tall or short, about one inch high usually, 

 sometimes two inches ; deep or yellowish green. Leaves crowded, 

 erecto-patent , the comal rather more spreading, but usually 

 incurved at apex, not recurved ; when dry circinate-incurved, pale 

 and glossy at back ; elongate linear-lanceolate , rather more than 

 1 line in length, carinate-concave above, tapering to apex but not 

 acute, margin plane, incurved at apex and forming with the 

 upturned point of the nerve a more or less strongly cucullate or 

 cymbiform tip; nerve yellowish, rather obscure above, vanishing 

 or excurrent in a very short mucro ; margin entire, or very 

 minutely and obsoletely denticulate above base ; basal cells 

 pellucid, a few hyaline, small, narrow, rectangular, gradually 

 becoming shorter and chlorophyllose, in upper part minute, 

 quadrate, very obscure, papillose. Perichaetial bracts sub- 

 sheathing, more acute than the leaves; seta reddish yellow, 

 capsule oblong or oval-oblong, slightly plicate when dry \ 

 peristome teeth reddish, rather short, unequally cleft, papillose. 



