43 2 HYPNACE^. 



The cells in P. depressum are faintly and minutely papillose, each cell having a 

 row of papillse — not a single one — on its face ; this being the only European species 

 in which such a structure is found, though it occurs in numerous, but not closely 

 allied, exotic mosses. The papillse however seem to disappear more or less after 

 gathering, and can only be seen quite satisfactorily in fresh specimens. They are 

 best observed by viewing the back of a dry leaf, in profile, with a high power. 



2. Plagiothecium Borrerianum Spruce (Hypnum elegans 

 Hook., sec. Schp. et plur. auct.) (Tab. LV. D.). 



In smooth, low, dense patches of a pale shining green ; 

 branches procumbent or ascending, mostly numerous, slender, 

 pointing one way, almost simple, complanate. Leaves sub- 

 distichous, complanate, or slightly depressed, the points frequently 

 curved downwards, not pointing upwards, hardly altered when 

 dry and very glossy, §-§ line long, ovate-oblong or oblong- 

 lanceolate, gradually narrowing from about the middle, then 

 quickly narrowed to a rather short, fine, sometimes flexuose 

 acumen, rounded at base to a rather narrow, not decurrent 

 insertion, one wing frequently infiexed, but plane at margin, 

 entire except at the acumen, which is more or less distinctly 

 denticulate, very rarely entire ; nerve double, short, frequently 

 very faint. Cells linear, pointed, very narrow, 20-30 times as 

 long as wide, about 80 /* long and 3-4 /x wide ; almost uniform to 

 base, or with a very few at basal angles sub-rectangular, but 

 indistinct. Capsule shortly oval, wide-mouthed and somewhat 

 turbinate when empty, horizontal or sub-pendulous, hardly 

 curved, smooth ; lid conical, obtusely pointed. Peristome yellow. 

 Dioicous. 



Var. /3. collinum Wils. Branches erect, leaves sub-secund . 



Hae. On the ground in woods, on rocks, etc. ; principally in mountainous 

 districts. Frequent. The var. $ rare. Fr. very rare, spring. 



There has been much diversity of opinion as to the identity or non-identity of our 

 European moss with the American plant described by Hooker under the name of 

 Hypnum elegans. The two plants are without doubt closely allied, and several 

 recent writers, considering them identical, have restored to our plant the specific name 

 of Hooker, as it was formerly described by Wilson, Schimper, etc. Spruce, however, 

 who first described the European plant, remained of the opinion that the two were 

 distinct, pointing out the distinguishing characters, some of which seem to have value. 

 I have therefore retained his name P. Borrerianum. 



P. Borrerianum may usually be recognised without much difficulty, by the small, 

 non-decurrent, narrowly tapering leaves, and very narrow areolation. P. silesiacum, 

 P. denticulatum and P. depressum are the only ones which are at all liable to be 

 confounded with it ; the differences between it and the former are pointed out under 

 that species. P. denticulatum is as a rule larger, with larger, more shortly and 

 widely pointed leaves, having much laxer areolation, the cells more than twice as long 

 and twice or even four times as wide ; in the var. aptychus, however, there is a much 

 nearer approach to the present plant ; but the leaves are rarely so finely pointed, the 

 cells, so far as I have observed them are hardly ever less than 120 p. in length, 



