312 FUNGI. [Didymium, 



brittle, inner very tliin hyaline ; columella none, sporidia black- 

 brown. Klotzsch! in Hook. Herb. 

 On bark, Appin. Capt. Carmichael. 



9. D. glohosum, Pers. {globose tvhite Diderma) ; sessile glo- 

 boso-hemispheric, outer peridium white, inner^cinereous, colu- 

 mella globose, sporidia dingy-brown black. Pers. Disp. t. 4. 

 f. 4, 5. Ditm. in St. Deutsch. Fl. l.t.6. Hook. Scot. 2. p. 12. 



Grev. Fl. Ed. p. 453. Sc, Crypt. Fl. t. 122. Fr. Syst. Myc, 

 V. 3. p. 106. 



On oak and beech leaves, &c. Common. 



10. D. cyanescens, Fr. {amorphous Diderma) ; sessile-adnate, 

 subrotund but irregular, outer peridium thick white, inner 

 glaucous, columella none, flocci and sporidia black-brown. Fr, 

 Syst. 3Iyc. v. 3. p. 109 D. difforme, Alb. ^^ Schw. Consp. p. 90. 



On dead oak leaves. Appin. Capt. Carmichad. — Fries gives as 

 the habitat, living leaves of Oxcdis. The specimens before me have a 

 crustaceous, white, outer peridium, like the shell of some small egg; 

 inner peridium in the dry state brownish, except at the base where it is 

 adnate and rufous. 



11. D.deplandtum, Vv. (depressed Diderma) ; sessile rounded, 

 outer peridium thick white, inner very thin hyaline, columella 

 and flocci none, sporidia black-brown. Fr. Syst. Myc. v. 3, 

 p. 110. 



On dead oak leaves. Appin. Captain Carmichael— V^hen the 

 sporidia have fallen out, the base within is of a somewhat tawny tinge. 

 i find a (ewjlocci. The Appin specimens form reticulated masses. 



86. Didymium. Schrad. Didymium. 



Inner peridium very delicate, membranaceous, bursting irre- 

 gularly, externally clothed with the bark-like outer peridium, 

 which breaks up into little furfuraceous scales or mealy down. 

 — Name, didviJ^og, double. 



* Stipitate, stem distinct. 



1. D. hemisphtericum, Bull, {liemispherical Didymium) ; peri- 

 dium hemispherical depressed erect, clothed with a dirty- white 

 veil, beneath piano- umbilicate, stem short thick dirty- white, 

 columella obsolete, sporidia dingy-brown black. Fr. Syst. Myc, 

 V. 3. p. 1 15. — Ret hemisphcerica, Bull. t. 446./. 1. Sow. ! 1. 12, 

 {marked 13.) With. v. 4. p. 353. 



On leaves, twigs, &c. Hampstead, Hornsey, Wanstead, &c. Sowerbij. 

 —Fries criticises Sowerby's figure ; but, as it appears to me, without. 

 1-eason, the original specimens being such as they are represented. 

 The curious, flat, subhemispherical peridia, with a broad shallow 

 umbilicus beneath, and the short, dirty-white stem are sufficient proof 

 that it is the true plant. 



2. Z>. squamulosum, A. & S. (squamulose Didymium) ; perl- 



