468 HYPNACE^E. 



the more solid less denticulate leaves with less marked auricles, and from both by the 

 numerous paraphyllia. The var. gracilescens on the other hand is a very distinct and 

 extremely pretty form, coming nearer to H. sulcatum, but rather more robust and 

 with longer, proportionally narrower leaves more of the falcatum form, with longer 

 nerve and narrower cells. It is much like H. Bambergeri, but the nerve at once 

 distinguishes it. 



* Hypnum sulcatum Schp. (Amblystegium glaucum var. 

 sulcatum Lindb.) (Tab. LVIII. B.). 



Resembling H. falcatum var. gracilescens but still more 

 slender ; stems more or less regularly pinnate, extremely slender, 

 soft or rigid, more or less prostrate or ascending; radiclesy<?a/ 

 or none, paraphyllia numerous. Tufts dull greyish green or 

 yellowish. Leaves very small, hardly Yz line long, regularly 

 falcato-secund or hamate, irregularly but distinctly plicate, widely 

 ovate and suddenly acuminate, or ovate and more gradually 

 tapering, but wider and shorter, proportionally, than in H. 

 falcatum, nerve comparatively weak, sometimes extremely faint, 

 but usually wide at base and soon becoming narrow, reaching 

 usually about half way, sometimes more ; margin sinuolate or 

 obsoletely denticulate ; cells short, elliptic-linear , thin- walled, 

 4-6 times as long as wide, but somewhat variable ; angular cells 

 large, orange, forming rather distinct auricles usually reaching to 

 the nerve. Fruit unknown. 



Hab. Wet alpine rocks, very rare ; Ben Lawers. 



This is probably sufficiently distinct from H. falcatum in the wide leaves, short, 

 often faint nerve, and especially the short lax areolation, to be considered a sub-species 

 rather than a variety, though it must be held to belong to that plant rather than to 

 H. commutatum, of which however it has the branching. The var. subsulcatum 

 Schp., indicated from Ben Lawers, appears to be a slight form only, and an approach 

 to H. falcatum var. gracilescens. There may indeed be found a great number of 

 forms more or less intermediate between the two plants ; and in the condition of the 

 nerve, especially, a wide range of variation may be found even among the leaves 

 from a single stem. There appears little doubt that H. Breadalbense F. B. White 

 represents one of these forms, and hardly differs from the var. subsulcatum. 



H. sulcatum is fairly abundant about the summit of Ben Lawers, but occurs 

 nowhere else, I believe, in our islands. 



C. DREPANIUM. 



Plants usually more or less pinnately branched, sometimes 

 very regularly plumose. Leaves mostly small, strongly and 

 regularly falcate or circinate, or less curved, but secund and 

 homomallous, then usually pointing upwards ; nerveless or with 

 a short double nerve, more or less longly and finely acuminate. 

 Median cells long and narrow, angular usually distinct. Plants 

 rarely paludal. Paraphyllia few, or none. 



