4 LECANO-LECIDEEI [OYALECTA 



Hab. On rocks in high latitudes. — Distr. Somewhat rare. — B. M. 

 Agron, Cleveland, Yorksliire ; Tarnbrook Fell, Lancashire ; Aran 

 ]\Ia\vddwy, Merioneth ; Kylemore, Conneniara, Galway ; near Killin, 

 Perthshire ; ]iear base of 13en Cruachan and Ballachulish, Argyll. 



Ordkr IV. LECIDEACE^. 



Thallus minutely squamulose or crustaceous, sometimes 

 obsolete ; algal cells (gonidia) Chlorophycese. Apothecia discoid or 

 patellate with proper margin only ; spores usually eight in the 

 ascus, sometimes fewer or more, simple or variously septate, 

 colourless or coloured. Spermogones immersed; spermatia elon- 

 gate, elliptical or cylindrical. 



This Order as defined above includes the Lichens classified 

 generally under the single comprehensive genus Lecidea by 

 Nylander in Mem. Soc. Cherb. v. pp. 119-127 (1837), by Leighton, 

 Lich. Flora, pp. 248-358, ed. 3, pp. 240-389, and by Crombie, 

 Lich. Brit. pp. 62-94 and in Grevillea xxii. pp. 8-11 and 57-60 

 (1893-4). The view held by early writers that the form of the 

 spores is a character of generic importance, has been revived 

 by recent lichenologists, and the species have been arranged 

 according to spore characters in the following order : — 



Apothecia cup-like, brightly coloured, marginate. 



Spores colourless, septate or muriform 70. Gyalecta. 



Apothecia discoid or patellate blackish or coloured. 

 Spores colourless. 

 Spores simple. 



8 or fewer in the ascus 71. Lecidea. 



Many in the ascus 72. Biatorella. 



Spores septate. 



1-septate 78. Biatorina. 



3- or pluriseptate, fusiform 74. Bilimbia. 



Pluriseptate, acicular 75. Bacidia. 



Spores brown. 



1-septate 76. Buellia. 



3-septate (parasitic) 77. Leeiograplia» 



Spores colourless or becoming brown. 

 8 in the ascus : 



Muriform (sometimes 1-3 -septate 



in species 1) 78. Rhizocarpon. 



1 in the ascus : 



Muriform, large 79. Bombyliospora. 



Elongate -pluriseptate, large 80. Lopadium. 



70. GYALECTA Ach. Lich. Univ. p. 30 (1810). (PL 4 ) 

 Thallus granular, pulverulent, or nearly obsolete ; algal cells 

 Trentepohlia. Apothecia brightly coloured, concave, with a 

 prominent proper margin, somewhat urceolate-patellate ; asci 

 usually 8- rarely many-spored ; spores variously septate, or 

 muriform. Spermogones w^ith almost simple sterigmata and 

 straight rather short spermatia. 



