NEW AND RARE MOSSES FROM SCOTLAND 241 



of Ben Lawers, and scarcely anywhere else in Great Britain, 

 have such close relationships to those occurring on or near 

 the eastern shores of the more northern parts of North 

 America ? Of such I recall three mosses, Mollia fragilis 

 (Drum.), Hypnum hispidnlum (Brid.), and Climacium epigceum, 

 besides several lichens. 



I have still no clue to anything in the way of a feasible 

 explanation, but I think it right to ventilate the question 

 for the sake of others who may have a wider range of facts 

 on which to frame, at least, a consistent theory. 



In July and August of 1908 at Onich, near Fort 

 William, I came across a large congeries of the minuter 

 Orthotricha growing, for much the greater part, in cracks of 

 the bark of the older Elder bushes. Along with them grew 

 almost invariably small tufts of the curious Tor tula papillosa 

 (Wils.), as well as, although less frequently, patches of 

 Orthotrichum diaphanum (Schrad.), two rather anomalous 

 species of mosses. All of these forms had several character- 

 istics in common, viz., their minuteness, dark lurid-green 

 colour, blunt and rounded apices to the leaves in varying 

 degree, but generally as blunt as in O. obtusifolium (Schrad.). 

 The main character is the revolute margins of the leaves 

 in their lower half or a little more, while they are more 

 commonly merely reflexed upwards almost to the blunt 

 apex. Meanwhile I shall describe one of these where the 

 capsule is long and slender, longer indeed than that of 

 O. tenellum (Bruch). 



Orthotrichum prasinellum. In small, rather loosely 

 aggregated tufts or patches ; stems upright, about a quarter 

 of an inch long, rarely longer, simple, occasionally emitting 

 a short branch ; leaves closely arranged around stem, im- 

 bricated and straight when dry, spreading a little when 

 moist, narrowly elliptical with round blunt apices, either 

 entire or slightly erose, or showing at times a broad very 

 short square-topped protrusion about .08 mm. broad and 

 nearly as much in height, margin entire, revolute from a 

 half to a whole round of the spiral but not more ; pagina 

 only very feebly papillose, often papillae scarcely perceptible ; 

 nerve narrow and thin, lat. near base, .O34-.O4 mm., 

 tapering a little and vanishing rather abruptly below apex ; 

 76 E 



