HYPNUM. 



475 



Hab. Alpine rocks ; very rare. Ben Lawers (Jameson, 1890). Fruit very 

 rare, almost unknown. 



There can be no doubt that the plant gathered by the Rev. H. G. Jameson is 

 identical with H. Heufleri Juratz., and this appears to be the same species with 

 Stereodon revolutus, described by Mitten in the Musci Indise Orientalis, 1859. If the 

 characters italicised are borne in mind there will be little difficulty in identifying it, 

 though this is probably impossible in the field, at least with any degree of certainty. 

 It is quite different from H. cupressiforme var. minus in the gradually tapering plicate 

 leaves with the margin very longly and strongly revolute. That species and some 

 others frequently have the leaves somewhat rugose when dry, but here they are 

 distinctly plicate longitudinally, and in the more robust stems this forms a marked 

 and indeed easily recognised character. 



20. Hypnum hamulosum B. & S. (Stereodon hamulosus 



Lindb.) (Tab. LVIII. I.). 



Very slender, resembling some slender, dense forms of H. 

 cupressiforme; bright yellow or yellowish green ; stems more or 

 less erect, or ascending, irregularly or pinnately branched. 

 Paraphyllia very few or none. Branches very slender, with the 

 leaves regularly imbricated in two rows, smooth and glossy at 

 back, strongly falcate, hooked at the tips of the stems, very 

 small, about i line long, ovate-lanceolate, longly and finely 

 acuminate to an almost filiform, hamato-circinate point, entire or 

 obsoletely denticulate, almost or quite nerveless, plane at margin, 

 concave ; areolation rather short, 8-15 times as long as wide, 

 thin-walled, linear, obtuse, almost uniform throughout the leaf, a 

 very few at angles sub-quadrate , small, not forming hyaline nor 

 distinct auricles. Capsule small. Autoicous. 



Hab. Alpine rocks, very rare ; Scotch Highlands ; Ireland. Fr. summer. 



A delicate species, most closely allied to H. callichroum, but differing in its more 

 constantly slender habit, more erect stems, autoicous inflorescence, shorter areolation, 

 and, above all, in the extremely few angular cells and total absence of the inflated 

 hyaline auricular cells, characteristic of that species. It is also more constantly 

 yellow, never bright green, and the acumen of the leaves though very fine is usually 

 shorter, and somewhat less flexuose when dry. It differs from H. revolutum in the 

 plane margin of the leaves, and from H. Bambergeri in the more slender habit, 

 autoicous inflorescence, less numerous and less distinct angular cells. 



21. Hypnum callichroum Brid. (Stereodon callichrous 



Brid.) (Tab. LVIII. J.). 



In wide, very soft tufts, more or less prostrate or ascending, 

 rarely erect ; bright green or yellowish green, reddish yellow 

 within ; very glossy and even brilliant when dry. Stems 

 irregularly pinnate, very slender, branches more or less flexuose 

 and curved. Leaves elegantly circinate-secund , \-\ line long, 

 from a rather dilated base, widely oblong-lanceolate, gradually 



