RACODIUMJ CCENOGONIACE^ 3 



strand which is closely invested by irregularly branching fungal 

 hyphixj. Apothecia apical or lateral, shortly-stalked, discoid, 

 not carbonaceous ; paraphyses discrete, unbranched, sometimes 

 faintly septate ; spores eight in the ascus, colourless, fusiform or 

 elliptical, simple or 1 -septate. Spermogones with fusiform 

 straight spermatia. 



This genus belongs almost exclusively to warm regions ; it is 

 represented in Europe by one species. 



1. C. ebeneum A. L. Sm. — Thallus brownish-black, forming 

 a wide-spreading soft felt of much-branched iSlaments which are 

 constricted at short intervals ; algal cells Trentepohlia aurea, 

 surrounded, by dark-brown fungal hyphse which closely follow 

 the outline of the alga. Apothecia not seen. — C. germanicum 

 Gliick in Flora Ixxxii. p. 268 (1896). Conferva ebenea Dillw. 

 Conf. t. 101 (1809). Chroolepus ebeneus Ag. Syst. p. 36 (1824); 

 Hook, in Sm. Engl. Fl. v. p. 381. Cystocoleus ebeneus Thwaites 

 in Ann. Mag. Nat. Hist. ser. 2, iii. p. 241, t. viii. B. figs. 1-3 

 (1849). 



The species is probably not uncommon, and, in damp localities, it 

 spreads extensively over the substratum in round patches or in a 

 radiating fan-like manner. The thallus is often invaded by a whitish 

 Lepraria, which grows in scattered granules over the older parts of 

 the lichen. It has been frequently confused with Racodiuiii 7'icpestre ; 

 so that it is impossible for the most part to determine the plants 

 recorded by the older writers. Byssus petrcea nigerrima fibrosa 

 (observed by R. Richardson) Dill, in Ray Syn. Stirp. Brit. ed. 3, p. 57, 

 n. 8 (1724), and quoted in Dill. Hist. Muse. p. 9, t. 11 f. 18 (1741), 

 may be either plant. Byssus nigra Huds. Fl. Angl. ed. 2, p. 606 

 (1778), Engl. Bot. t. 702, and Dematium rupestre S. F. Gray Nat. 

 Arr. i. p. 588 (1821), share the same uncertainty. Filaments are 

 occasionally found intermingled with the alga Trentepohlia aurea. 



Hob. On rocks and stones, in shady localities. — Distr. Somewhat 

 rare in Great Britain. — B. M. Llanymawddwy, Merioneth ; Bridge- 

 north, Shropshire ; Sychnant, Conway, Carnarvonshire ; Bolton 

 Woods, Yorkshire; Kirkconnel, Springkell, Dumfriesshire; near 

 Killin, Perthshire ; Loch Morar, Inverness. 



69. RACODIUM Pers. Syn. Fung. p. 701 (1801). (PI. 3.) 

 Thallus composed of loose, branching filaments, dark-coloured. 

 Algal cells, CladopJiora, forming a central strand, the fungal 

 hyphse growing in straight lines, and forming a closely investing 

 outer sheath. Apothecia and spermogones unknown. 



1. R. rupestre Pers. I. c. — Thallus brownish-black, felt-like, 

 usually occurring in small patches, more rarely wide-spreading; 

 filaments straight, not constricted, branched, fungal hyphse very 

 dark-coloured, obscuring the central algal strand. 



As stated above, this plant has been frequently included with 

 Coenogonium ebeneum under the comprehensive name Byssus nigra. 



B 2 



