404 LICHENACEI. [LECANORA. 



gubimbricatus Relh. Fl. Cantab. 1785, p. 427 ; With. Arr. ed. 3, 

 iv. p. 18. 



The thallus is small or moderate (1-4 inches in diameter), often 

 greyish -brown, rarely somewhat leaden-coloured, and at times in old 

 plants becomes centrifugal. In some situations the thallus is reddish- 

 grey with the apothecia brownish-red, when it seems to be var. /3. myr- 

 rhina Fr. (non Ach.) Lich. Eur. p. 124; Cromb. Grevillea, xviii. p. 47. 

 This, however, evidently arises from its being suffused either with 

 peroxide of iron or with urine, so that it is only an accidental state. Our 

 British specimens are well fertile, the apothecia, though central, being 

 numerous, occasionally crowded and then subangulose. The spermogones 

 are frequent, dark-brown, with simplish sterigmata and spermatia 

 0,006-7 mm. long, about 0,001 mm. thick. 



Hob. On rocks and walls, usually on the coping of bridges, in lowland 

 and upland districts. Distr. Here and there throughout England, in N. 

 Wales, reported also from S.W. Scotland (Cathkin) ; very rare in the 

 Channel Islands ; not seen from Ireland. B. M. : Island of Guernsey. 

 Bury St. Edmund's, Suffolk ; Clare Hall Bridge, Cambridge ; near Stroud, 

 Gloucestershire ; Hale's End, Malvern and Pershore Bridge, Worcester- 

 shire ; near Congerstoue, Leicestershire ; Oversley Bridge, Warwickshire ; 

 Garn Bridge, Conway Castle, Denbighshire ; Barnard Castle and Egle- 

 stone, Durham ; Kirkby Lonsdale, Westmoreland. 



79. L. circinatula Xyl. Flora, 1883, p. 100. Thallus small, ap- 

 pressed, diffract, radiately divided at the circumference, the radii 

 plane, dark-greyish or brownish-grey (K + yellow, CaCl ). Apo- 

 thecia innate, submoderate, plane, dark-brown, the thalline margin 

 thin, entire ; spores 8nae, ellipsoid, about 0,007 mm. long, 0,005 7nm. 

 thick ; paraphyses thickish, jointed ; hymenial gelatine bluish, then 

 tawny wine-red with iodine. Cromb. Grevillea, xii. p. 89. 



Closely allied to L. circinata, from which it is distinguished by 

 the different reaction and by the smaller thallus and spores. The apo- 

 thecia are numerous and crowded except at the immediate circumference. 

 The spermogones have the sterigmata slender, 2-3-jointed, with straight 

 bacilliform spermatia, 0,0035-45 mm. long, 0,0005 mm. thick. 



Hub. On siliceous stones in a maritime district. Distr, Only very 

 sparingly in S. England. B. M. : Near Beachy Head, Sussex. 



E. Apothecia lecanorine or at times biatoroid; spores 8nse, very 

 rarely 8-16na3, simple, rarely 1-septate, colourless : hymenial 

 gelatine variously tinged with iodine. Spermogones with 

 simple sterigmata and acicular, arcuate, very rarely straight 

 spermatia. 



a. Thallus normally subeffigurate, K . 



80. L. galactina Ach. Lich. Univ. (1810) p. 424. Thallus sub- 

 orbicular, appressed, verrucoso-diffract, lobato-crenate at the circum- 

 ference, opaque, subpulverulent on the surface (K ). Apothecia 

 moderate, or somewhat small, adnate, somewhat plane, pale- or 

 brownish-testaceous, white-pruinose or naked, the thalline margin 

 at length crenulate and often flexuose ; spores ellipsoid or oblong, 



