10 LECANO-LECIDEEI [lECIDKA 



Well charactcri/ed by tlic form, septation and size of the spores, 

 which readily distinguish it from all the allied species. The apothecia,. 

 somewhat scattered, arc semitransparcnt, and become in age less 

 concave, with the margin darker. At times the wliole plant is more 

 or less infested by L('j)raria rubens Ach. 



A plant corresponding with this in the form and septation of the 

 spores is L. chrysojiha'a Nyl. in Act. Soc. Linn. Bord. ser. 3, t. i.. 

 p. 438 (1856) ; but this is doubtfully British. Lecidca pallida Nyl. 

 I. c, with oblongo-fusiform 3-septate spores, is more probably a 

 fungus {cf. Nyl. Lich. Scand. p. 192). 



Hab. On smooth bark of trees in wooded maritime and upland 

 districts. — Distr. Somewhat rare in England and Wales ; rare in S.W» 

 Ireland ; not seen from Scotland or the Channel Islands. — B. M. 

 Near Ryde, Isle of Wight ; Lyndhurst, New Forest, Hants ; Lustleigh, 

 Devon ; Ashdown Forest, Tilgate, and Eridge Park, Sussex ; Twycross, 

 Leicestershire ; Barmouth, Merioneth ; Trefriw, Garn and Gwdir,. 

 Denbighshire ; Haughmond Hill, Shropshire ; Eglestone and Teesdale,, 

 Durham ; Keswick, Cumberland ; Dinis, Killarney, Kerry. 



71. LECIDEA Ach. Meth. p. 32 (1803); Nyl. emend, in 

 Mem. Soc. Cherb. t. iii. p. 181 (1856). 



Thallus squamose, pulverulent, granulose, continuous, areolate, 

 rimulose, evanescent or absent ; hypothallus various, persistent 

 or indistinct. Algal cells Protococcus or rarely Trentepohlia. 

 Apothecia either discolorous (not black) and biatorine, or black 

 and lecideine, the proper margin often obliterated ; spores usually 

 eight in the ascus, ellipsoid or oblong, simple, colourless ; hymenial 

 gelatine variously tinged with iodine. Spermogones with sper- 

 matia acicular, straight, rarely arcuate, or shortly cylindrical. 



This extensive genus has been grouped under four sections. The 

 spores are colourless and simple or rarely faintly 1- septate ; the asci 

 are 8- or sometimes 6-spored, excepting in the section Megalospora 

 which contains one species with a 1- or 2-spored ascus. The term 

 biatorine, from Biato7'a, has been applied to those apothecia that are 

 lighter in colour and soft in texture, while lecideine signifies the 

 dark almost black fruits that are carbonaceous and hard, and that 

 belong more particularly to the Eulecidece. There is, howcA^er, no 

 clear line of demarcation, as the colour and form of the fruits change 

 with age. The genus is very well represented in our islands, where a 

 considerable number of species seem to be endemic. The chemical 

 reactions, which have been given as far as possible, will be found to 

 be useful in distinguishing plants which otherwise might readily be 

 confounded. The species within the genera have been grouped as 

 nearly as possible in the order followed by Nylander and subsequently 

 by Hue and Crombie. 



Thallus distinctly squamulose § i. Psora (1-15). 



Thallus variously crustaceous. 

 Ascus 8-spored. 



Apothecia lighter in colour § ii. Biatora (16-76). 



Apothecia dark and carbonaceous § iii. Eulecidea (77-200). 

 Ascus 1- or 2-spored. 



Apothecia dark § iv. Mycoelastus (201-2). 



