HYPNUM. 473 



would appear more accurate to confine the name to the plant described above, as the 

 very slender habit is practically the only character the two forms have in common. 



The var. ericetorum somewhat resembles H. imponens, the description of which 

 may be consulted in this connection. 



The var. elatum is very striking, at least in its most marked forms, and quite 

 different in its erect, tumid stems from all other states of this species. 



17. Hypnum imponens Hedw. (Stereodon imponens Brid.) 



(Tab. LVIII. E.). 



Resembling H. cupressiforme, notably var. ericetorum; 

 differs in the following characters. Stems more solid and rigid, 

 reddish brown ; more closely, regularly and complanately pinnate ; 

 plants almost always of a golden yellow ; robust, in large tufts. 

 Stem-leaves usually somewhat complanate, being less crowded, 

 less concave, more spreading in the lower part, so as to render 

 the stems flattened, in the flatter hardly channelled acumen 

 strongly falcate or hamate ; when dry the leaves are usually 

 somewhat rugose ; branch-leaves narrower, less complanate. 

 Stem-leaves wider at base than in H . cupressiforme , triangular- 

 oblong, more gradually acuminate, margin usually very narrowly 

 recurved in the lower part , above distinctly but somewhat distantly 

 denticulate ; insertion wide, usually straight, not excavate nor 

 decurrent ; median cells longer and narrower, basal often bright 

 orange, angular less numerous but larger, more pellucid, with 

 scarcely any of the small opaque upper ones, forming very small, 

 distinct auricles, usually of a rich orange brown. Paraphyllia 

 usually numerous. Perichaetial bracts plicate. 



Hab. Heaths, rocks, etc. ; very rare. Fr. very rare, autumn. 



The orange, distinct angular cells, more pellucid and larger, the wider more 

 strongly denticulate leaves and the general habit, as well as the more rigid, brown 

 stems, render this plant, if not at once distinguishable in the field, at least easy of 

 recognition under the microscope. Undoubtedly however, it is linked with H. 

 cupressiforme by a more or less complete chain of forms, and the characters even as 

 given above are all either somewhat comparative or occasionally inconstant. I have 

 for instance a plant with the general appearance of this moss, with brown stems and 

 leaves somewhat intermediate in form, but with the angular cells typical of H. 

 cupressiforme ; and other similar forms of the latter species unite it with the present 

 plant. It is possible therefore that Boulay is right in making it a sub-species of that 

 moss ; but the angular cells, which are certainly of great value in the classification of 

 this Section, justify its separation, I think, in conjunction with the other characters. 

 The plicate perichsetial bracts appear also to give an important character, but the fruit 

 is too rare for this to be of practical value. 



18. Hypnum PatienticB Lindb. (Stereodon arcuatus Lindb. ; 

 Hypnum arcuatum Lindb., Schp. Syn.) (Tab. LVIII. F.). 



Resembling the most robust forms of H. cupressiforme, but 

 still larger ; stems more or less prostrate, with ascending 



