:324 LICHENACFJ. [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. pusfulata in the external appearance of the 

 thallus. thouo;!! agreeing with it in the character of the apothecia. It is 

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

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

 apothecia being constantly lecanoroid and not becoming g^-rose. The few 

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

 are, however, well fertile, the apothecia b^-ing numerous, though some- 

 what small. 



Mab. On granitic boulders in exposed alpine places. — Disfr. Foimd 

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

 Summit of C'airutoul. Braeniar, Aberdeenshire. 



55. GYROPHORA Aeh. iletli. 

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

 p. 303. — Thallus naked or fibrillose 

 beneath. Apothecia lecideiue, usually 

 more or less gyroso-plicate ; hypo- 

 tliecium usually brown : spores 8nfe, 

 simple, Colourless ; hymenial gela- 

 tine bluish and then sordid wine- red 

 with iodine. Spermogones immersed ; 

 spermatia short, cylindrical. 



Distinguished from Umbilicciria by 

 the apothecia being lecideine, with the 

 perithecium diffeiing in texture from 

 the cortex. The structure of the thallus 

 scarcely differs from that of subgen. 

 Agi/ro}hora. The apothecia are 

 either simply lecideine or beautifully 

 gyroso-cou)plicate, each individual epi- 

 thecium beir.g narrow and margined. 

 The spermogones 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. 



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

 (1839) p. 230.— Thalhis 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 sparinglj- 



Fig. 54. 

 Gyrofhora cyhndrica Ach. — a. 

 Vertical section of thallus, vrith 

 lateral portiou of a spermo- 

 gone, X200. h. Vertical sec- 

 tion of an apothecium, X^O. 

 c. Theca and paraphvsis, 

 X30(). d. Three spores, X 500. 

 e. Sterigniata and spermatia, 

 X 500. 



fibrillose in the centre, blackish or greyish (Iv_, CaCl, . ^|). Apo- 

 thecia at length convex, immarginatc. gyroso-plicate; spores 0,014-18 



"ss > 



