UMBXLICA1UA. 



177 



they are immersed, have a thin, blackish envelope, a greyish 

 horny tissue, and are apparently devoid of a free cavity. 

 The sterigmata are ramose and solid, closely aggregated, 

 forming a most compact or dense tissue; the spermatia 

 very numerous, fine, and straight. Subjected to ammonia- 

 cal maceration, this species yields a very rich orchill, and is 

 largely imported by the London orchill- maker from Norway 

 and Sweden under the commercial designation of " Pustu- 

 latous Moss." Linnaeus speaks of it as yielding a red dye, 

 and Withering as capable of furnishing also a black paint. 



3. Umbiltcaria polymorph a (7roXu9, many, and fjuopcfyrj, 

 shape) . Thallus greyish-pruinose or fuliginose, ciliated with 

 rigid, ramose, black fibres, or naked, — below ochroleucous 

 or blackish-grey, hirsute or naked; apothecium sessile or 

 pedicellate, concentrically plicate, margin thin, at last oblite- 

 rated. 



There are several varieties, depending on the thallus being 

 mono- or polyphyllous, — its surfaces smooth or roughened, 

 and pale or dark-coloured, — its margins ciliate or naked, — 

 and on the varying characters of the apothecia. Of these 

 the most important and common are var. cylindrlca (E. B. 

 522) in which the thallus is usually somewhat simple or 

 smooth above, with fimbriate or fibrillose, sometimes naked, 



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