Perichaena corticalis. 115 



(Rostafinski's Synonyms.) 



Perichaena vaporaria, Schw., Am., 2311 (1831). 

 Perichaena depressa, Lib., Exs., n. 378 (1837). 

 Stegasma depressum, Cda., Ic. V., f. 13 (1842). 



Perichaena corticalis, Rost. (figs. 114 117). 



Sporangia spherico-depressed, crowded, dehiscing in a circum- 

 scissile manner, lid convex, brown, bluish-purple, sometimes 

 whitish, smooth ; mass of capillitium and spores pale yellow ; 

 capillitium scanty, sometimes almost obsolete, threads thin, 

 smooth, or here and there notched ; spores globose, warted, warts 

 variable in size, sometimes very indistinct, at others well- 

 developed, never smooth, 9 12 ju, diameter. 



Perichaena corticalis, Rost., Mon., p. 293, figs. 188 ; Cke., Myx. 

 Brit., 78, fig. 188 ; Sacc., Syll., n. 1435 ; Raunk., Myx. Dan., 

 p. 53. 



Perichaena fa-sco-atra, Rost., Mon., p. 294 ; Cke., Myx. Brit., 

 78 ; Sacc., Syll., n. 1436. 



Perichaena quercina, Fr., Gast., p. 12. (Specimen from Fries 

 in Herb., Kew.) 



Exsicc. Sydow, Myc. March., 1669; Karst., Fung. Fenn., 

 179; Fuckel., Fung. Rhen., 1899; Berk., Brit. Fung., 47; 

 Desm., Or. Fr., Ser. I., 671. 



On bark and wood. Britain (Lyndhurst, Kew, Derby, Castle 

 Howard, Yorks ; Carlisle, Edinburgh, Appin, N. B.) ; Europe ; 

 Canada ; United States ; W. Australia ; Ceylon. 



Very closely allied to P. depressa, if indeed really distinct as 

 a species, the less depressed sporangium and scanty capillitium 

 are the distinguishing features of the present species. 



In some specimens tha wall of the sporangium has a dense 

 layer of angular particles of lime, and is consequently nearly or 

 quite white externally, in others the lime is scanty and in its 

 place a layer of amorphous, coloured granules of organic matter 

 which give the brown or reddish-purple colour to the sporangial 



