I.ECAXORA.j LKl'AXO-LECIDEKI. 403 



section ofLecanora. The thallus is rather scattered, greenish-grey when 

 moistened, usually but sparingly fertile ; though in one corticolous frag- 

 ment the apothecia are somewhat numerous. 



Hub. On mossy and naked trunks of trees in upland situations. Distr. 

 Extremely local aud scarce in N. Wales, where it has not recently been 

 met with. B. M. : Cwni Bychan and Crafnant, Merionethshire. 



D. Thallus placodioid. Apothecia lecanorine ; spores 8nte, ellipsoid, 

 rarely subglobose, simple, colourless ; paraphyses jointed. 

 Spermogones with simple or shortly jointed sterigraata and 

 cylindrical, moderate, straight spermatia. 



77. L. melanaspis Ach. Lich. Univ. (1810) p. 427 ; Nyl. Flora, 

 1873, p. 18, nota. Thallus suborbicular, adnate, thiunish, areolate 

 or verrucoso-rugose in the centre, radiato-laciniate at the circum- 

 ference, greyish or leaden-greyish, the radii convex, multifid (K , 

 CaCl ). Apothecia small, appressed, plane, at length convex, the 

 thalline margin entire ; spores ellipsoid, 0.011-13 mm. long, 

 0,008-10 mm. thick ; hymenial gelatine bluish, then wine-red with 

 iodine. Leight. Lich. Fl. ed. 3, p. 201. Lecanora alphoplaca var. 

 melanaspis Stirt. Scottish Naturalist, iv. p. 28. 



Differs from L. alphoplaca (Wahl.), the typical species of this section, 

 of which it has sometimes been made a variety, and which is not found 

 in Britain, in the negative reaction with K, among other distinctive cha- 

 racters of the thallus and apothecia. I have, however, seen no British 

 specimen, and regard it as of doubtful occurrence in the locality re- 

 corded. 



Hub. On rocks in a mountainous region. Distr. Said to have been 

 found in the S.W. Highlands of Scotland (Ben Brecht, Argyleshire). 



78. L. circinata Ach. Lich. Univ. (1810) p. 425 Thallus orbi- 

 cular, closely adnate, verrucoso-areolate in the centre, radiato-plicate 

 at the circumference, greyish or greyish-white, the radii contiguous, 

 narrow, somewhat plane or convex (K or -(-yellowish). Apothecia 

 small or submoderate, innate, at first suburceolate, then plane, 

 brown or dark-brown, the thalline margin thin, entire ; spores ellip.- 

 soid, 0,011-15 mm. long, 0,0065-85 mm. thick; hymenial gelatine 

 bluish, then reddish with iodine. L. circinata Cromb. Lich. Brit, 

 p. 49 ; Leight. Lich. Fl. p. 195, ed. 3, p. 179 ; Hook. Fl. Scot. ii. 

 p. 50. Sqnamaria circinata Mudd, Man. p. 130 ; Sm. Eng. Fl. v. 

 p. 196. Placodium circinatum Gray, Nat. Arr. i. p. 448. LicJien 

 circinatus Pers. in list. Ann. Bot. vii. (1794) p. 25, Eng. Bot. t. 

 1941. A well-marked species, of which the type apparently does 

 not occur in Britain, but only the peculiar form subcircinata Xyl. in 

 litt., differing merely in the thalline reaction (K + yellow, then 

 saffron-red). This being but a supplementary reaction, the plant 

 is not now regarded by Nylander as constituting a distinct species as 

 in Flora, 1873, p. 18, subsp. Cromb. Grevillea, xviii. p. 47. LicJien 



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