324 



LTCHENACET. 



[UMBILICARIA. 



plane ; spores often obsoletely curved, 0,013-16 mm. long, 0,005-6 

 mm. thick. Cromb. Journ. Bot. 1882, p. 273. 



Differs very much from U. jmstulata in the external appearance of the 

 thallus, though agreeing with it in the character of the apothecia. It is 

 well characterized by the somewhat rigid thallus having the upper sur- 

 face minutely areolate and the lower smooth and glabrous, as also by the 

 apothecia being constantly lecanoroid and not becoming gyrose. The few 

 British specimens are smaller than those of more boreal regions. They 

 are, however, well fertile, the apothecia being numerous, though some- 

 what small. 



Hab. On granitic boulders in exposed alpine places. Distr. Found 

 only very sparingly on one of the N. Grampians, Scotland. B. M. : 

 Summit of Cairntoul, Braemar, Aberdeeushire. 



55. GYROPHORA Ach. Meth. 

 (1803) p. 110; Nyl. Flora, 1875, 

 p. 303. Thallus naked or fibrillose 

 beneath. Apothecia lecideine, usually 

 more or less gyroso-plicate ; hypo- 

 thecium usually brown : spores 8use, 

 simple, colourless ; hymenial gela- 

 tine bluish and then sordid wine- red 

 with iodine. Spermogones immersed ; 

 spermatia short, cylindrical. 



Distinguished from Umbilicaria by 

 the apothecia being lecideine, with the 

 perithecium differing in texture from 

 the cortex. The structure of the thallus 

 scarcely differs from that of subgen. 

 Agyrophora. The apothecia are 

 either simply lecideine or beautifully 

 gyroso-complicate, each individual epi- 

 thecium being narrow and margined. 

 The sperinogones have the spermatia 

 similar in size to those of Umbilicaria, 

 In several cases the chemical reaction 

 of the medulla with CaCl affords a valu- 

 able aid in the discrimination of spe- 

 cies otherwise with difficulty separable 

 from each other. 



Fig. 54. 

 Gyrophora cylindrica Ach. a. 



1. G. grisea Turn. & Borr. Lich. Br. 

 (1839) p. 236. Thallus monophyl- 

 lous, thin, minutely areolato-papillate, 

 somewhat lobed and crenate at the 

 margins, greyish-white or mouse- 

 coloured; beneath finely granuloso- 

 areolate, scabrous, naked or sparingly 



fibrillose in the centre, blackish or greyish (K^, CaCl~ red ). Apo- 

 thecia at length convex, immargin ate, gyroso-plicate; spores 0,014-18 



Vertical section of thallus.with 

 lateral portion of a spenno- 

 gone, X 200. b. Vertical sec- 

 tion of an apothecium, X30. 

 c. Theca and paraphysis, 

 X300. d. Three spores, X 500. 

 e. Sterigmata and spermatia, 

 X500. 



