CHIODECTON] CHIODECTONACEiE 261 



scripta Mudd Man. p. 253 (1861). Stigmatidium circumscriptum 

 Carroll in Journ. Bot. iii. p. 291 (1865); Cromb. Lich. Brit, 

 p. 101; Leight. Lich. Fl. p. 389; ed. 3, p. 412; f. dendrizum 

 Nyl. in Flora Ixiv. p. 188 (1881). 



Exsicc. Mudd n. 239 ; Larb. Lich. Hb. nos. 319, 320. 



The fertile verrucae are nofc distinguishable from the thick, deeply 

 cracked thallus. The arrangement of the apothecia is very varied ; 

 usually they are irregularly scattered, sparse, and very crowded 

 towards the centre of the thallus and arranged in dendroid radiating 

 lines at the circumference (f. dendrizum), a character which is fairly 

 constant in well-developed specimens. 



Hah. On shaded rocks, not calcareous, usually near the sea. — 

 Distr. Not uncommon in the Channel Islands and S. England ; rare 

 in N. England and S. and N. Ireland. — B. M. Jerbourg, Guernsey ; 

 Boulay Bay, Eozel, La Coupe, Belmonte Bay and Noirmont, Jersey ; 

 Pentire, St. Minver, Willcoe, Saltash, St. Peter's. Point and Banks of 

 the Tamar, Cornwall ; Lynmouth and Lydford, Devon ; Air^'holme 

 Wood, Cleveland, Yorkshire ; Killarney, Kerry. 



96. CHIODECTON Ach. Syn. Lich. p. 108 (1814). Syncesia 

 Tayl. in Mackay Fl. Hib. ii. p. 103 (1836). (PL 32.) 



Thallus crustaceous, thin or often rather thick. Algal cells 

 Trentepohlia. Apothecia black, immersed in the thalline 

 verrucse, aggregate or confluent ; hypothecium thick, blackish- 

 brown ; paraphyses slender, branched ; asci clavate ; spores 

 elongate-fusiform, 2-pluri-septate, colourless. Spermogones with 

 cylindrical straight or bent spermatia. 



Distinguished from other genera of the order by the deep black 

 stromatoid structure of the hypothecium which often connects the 

 apothecia at the base. 



1. C. albidum Leight. Angioc. Lich. p. 25, t. 8, f. 4 & 

 t. 9, f. 1 (1851). — Thallus whitish, thin, pulverulent, dotted 

 with white elevated roundish verrucae. Apothecia small, 

 immersed in the verrucae^ substellate, or solitary, confluent at 

 the base in a black stroma forming the hypothecium ; paraphyses 

 slender, distinct ; spores fusiform, colourless, 3-septate, 0,030-40 

 mm. long, 0,005-6 mm. thick. — Leight. Lich. Fl. p. 404 ; ed. 3, 

 p. 435 (excl. vars.). C. myrticola var. albidum Mudd Man. 

 p. 245 (1861) ; Cromb. Lich. Brit. p. 105. Syncesia albida 

 Tayl. in Mackay Fl. Hib. ii. p. 103 (1836). 



Hah. On shaded rocks. — Distr. Rare in S. and N. Ireland. — 

 B. M. Dunkerron, and between Kenmare and Killarney, Kerry. 



2. C. petrsBum Del. ex Nyl. in Act. Soc. Linn. Bord. ser. 3, 

 i. p. 418 (1856). — Thallus white, cretaceous, rather thick, and 

 lumpy or war ted, smooth. Apothecia immersed in the verrucae, 

 crowded or confluent, flat and somewhat depressed, whitish- 

 pruinose ; paraphyses slender, distinct, spores elongate-fusiform, 



