HYPNUM. 483 



large, f line long, spreading or erecto-patent, not densely- 

 crowded, not secund nor falcate, very soft, concave, widely oval, 

 slightly narrowed above the middle to a very broad, rounded, 

 obtuse apex, narrowed at base, obsoletely denticulate at tip, 

 nerve bi-trifid, very short and faint, rarely one branch longer and 

 reaching the middle of the leaf. Cells linear, flexuose, 10-15 

 times as long as wide ; at angles resembling those of H. palustre, 

 slightly more distinct, forming inconspicuous and ill-defined 

 auricles. Pericha;tial bracts denticulate above. Autoicous. 



Var. /8. Schimperianum Schp. (Hypnutn Schimperianum 

 Lorentz). More slender, in dense swollen tufts; leaves much 

 smaller, more shortly pointed, the auricles less distinct. 



Hab. Alpine rocks in streams, very rare. Ben Nevis ; Ben MacDhui. The 

 var. 0, Loch-na-gar ( Fergusson). Fr. summer. 



H. molle forms very soft, easily separating tufts, and by this and the broad, 

 rounded leaves may be known from H. palustre and H. arcticum, the only distinct 

 species with which it is likely to be confused, except H. ochraceum, which has often 

 the same soft texture, but which has almost constantly narrower, more tapering leaves, 

 and is always known by the distinct hyaline auricles. The differences between it and 

 H. dilatatum are pointed out below. 



The var. S is a slender form, with a different facies, but the characters are 

 superficial rather than structural. 



* Hypnum dilatatum Wils. (Amblystegium dilatatum Lindb.) 



(Tab. LIX. D.). 



Closely allied to H . molle, but somewhat more rigid, of a 

 dull green rather than brownish colour ; the leaves slightly 

 secund, sub -orbicular , hardly narrowed from the middle, but 

 rounded-obtuse at the summit, sometimes with a short, obtuse 

 apiculus ; cells longer, especially in the lower half of the leaf, 

 15-25 times as long as wide, the angular rather larger and more 

 distinct, frequently orange. 



Hab. Rocks in mountain streams, very rare. 



The characters italicised above will readily indicate the distinguishing characters 

 of this plant from H. molle, its nearest ally ; Boulay, indeed, makes it a variety of that 

 plant, but the characters appear of a certain weight, though hardly sufficient to 

 support its separation as a. species. It is a more difficult question which of the two 

 plants should be considered the type and which the sub-species ; H. molle was the 

 first described ; on the other hand H. dilatatum, on the continent especially, is much 

 the most widely distributed. 



H. arcticum differs in the more rigid habit, smaller leaves, shorter cells, and 

 longer, single nerve. 



