70 FUNGUS-FLOKA. 



On old weathered wood of oak, pine, &c. 

 Distinguished at once from S. Berlceleyanum by the 

 absence of the yellowish furfuraceous exterior. 



EHYTISMA. Fries, (figs. 1-3, p. 91). 



Ascophores crowded on a thin, broadly effused, black, 

 crust-like stroma; elongated, often more or less wavy, 

 finally gaping and exposing the pale disc ; asci clavate, 

 8-spored ; spores elongated, slender, hyaline, continuous, 

 arranged in a parallel fascicle in the asous ; paraphyses 

 slender, often curved at the tip. Conidia usually produced. 



Ehytisma, Fries, Vet. Akad. Handl. (1819), p. 104; 

 Cke., Hdbk., p. 755; Eehm, Krypt. -Flora, Disc, , p. 82; 

 Sacc, SyU., viii. p. 752. 



The species commence as parasites on living leaves, 

 forming conspicuous pitch-black patches, often of consider- 

 able size. Conidia are formed during the autumn or winter, 

 and ascospores the following spring, after the leaves are 

 partly decayed. 



Rhytisma acerinum. Fr., Syst. Myc, ii. p. 569 ; 

 Cke., Hdbk., p. 756; Eehm, Krypt.-Flora, Disc, p. 82; 

 Sacc, SyU., viii. n. 3083. 



Stroma forming slightly raised, irregularly circular, 

 black patches on the upper surface of living leaves, 1-2 cm. 

 across; ascophores gregarious on the stroma, elongated, 

 wavy, gaping at maturity and exposing the pale disc ; 

 stroma blackish; hypothecium hyaline; excipulum paren- 

 chymatous, cells minute, olive-brown; asci clavate, apex 

 narrowed, 8-spored; spores arranged in a parallel fascicle, 

 needle-shaped, apex obtuse, base pointed, hyaline, guttu- 

 late, often slightly curved, 60-80 x 1 * 5-2 • 5 yu, ; paraphyses 

 slender, equal, about 1 • 5 /x, thick, curled or wavy, at the 

 apex, hyaline. 



Xyloma acerinum, Pers., Syn. Fung., p. 104. 



Spermogonia. Spermatia cylindrical, ends obtuse, straight 

 or curved, hyaline, 6-9 X 1. 



Melasmia acerinum. Lev., Ann. Sci. Nat., ser. iii,, vol. v., 

 p. 276. 



