426 LicnEXACEi. [lecanoka. 



Form calcigena Xyl. ex Cromb. Journ. Bot. 1876, p. 361 

 (nomeu) ; Leight. Lich. Fl. ed. 3, p. 192. — ThaUus determinate, 

 thicker, areolato-diffract, greyish. Apothecia livid, subpruinose, the 

 thaUine margin entire. 



Differs in the characters given of the thalhis and apothecia. It ia 

 probably a good variety, but has been seen too sparingly to decide. 



Hah. On calcareous rocks in a maritime district. — Distr. Very local 

 and scarce in X. W. Ireland. — B. M. : Lettermore, Connemara, co. Galway. 



107. L. AgardMana Ach. Syn. (1814) p. lo2; Xyl. Lich. Scand. 

 p. 138. Thallus effuse, thin, contiguous, smooth, opaque, dark- 

 greyish (K — , CaCl — ). Apothecia small, at first innate, concave, 

 with "svhitish entire thalline margin, at length sessile, convex, im- 

 marginate, brownish-black, slightly pruinose or naked (epithecium 

 HXo rosaceous) ; spores ellipsoid. 0,010-14 mm. long, 0,004-5 mm. 

 thick : paraphyses thickish, brownish at the apices ; hymenial gela- 

 tine bluish with iodine. — Cromb. Grevillea, xviii. p. 69. 



A plant, according to Xylander in lift., allied to L. Hageyii, though the 

 apothecia are at length lecideoid. In the few British specimens the 

 thaUus is indistinct, so that they may be refen-ed to a furm ecrustacea 

 Cromb. The apothecia are numerous, though not crowded, and for the 

 most part epruinose. The ?permogoues are rarely present, with spermatia 

 0,012-15 mm. long, O.OOOo mm. thick. 



Hah. On calcareous rocks in a maritime district. Distr. As yet only 

 in X. Wales. — B. M. : Great Orme's Head, Carnarvonshire. 



108. L. prosechoides Xyl. Flora, 1872, p. 250. — Thallus deter- 

 minate, thinnish, areolate-rimose, whitish or sordid-yellowish (K— , 

 CaCl — }. Apothecia small or moderate, plane, somewhat prominent, 

 brownish or blackish, the thalline margin subentire ; spores 

 ellipsoid or oblongo-ellipsoid, occasionally 1-scptate, 0,008-12 mm. 

 long, 0,0045-55 mm. thick ; paraphyses discrete, moderate or 

 thickish, brownish or yellowish-brown at the clavate apices ; hy- 

 menial gelatine persistently bluish with iodine. — Cromb. Grevillea, 

 iii. p. 82. — Lecanora umhrina subsp. jirosecJioides Xyl. in Cromb. 

 Lich. Brit. (1870), p. 51 ; {orma prosechoides Leight. Lich. Fl. p. 208, 

 ed. 3, p. 191. To this Jlde Xyl. in Hit. is referable Lecanora 

 helicopis f. dilutior Xyl. Lich. Scand. p. 159, Carroll, Journ. Bot. 

 1866, p. 23, Cromb. Lich. Brit. p. 50 ; also PanneJia subfnsca var. 

 lainea Fr. Lich. Suec. Exs. n. 371. Lecanora prosecha {nan Ach.) 

 Leight. Lich. Fl. ed. 3, p. 224. — Brit. E:cs. : Cromb. n. 67; Larb. 

 Lich. Hb. n. 94. 



At first regarded as a subspecies of L. umhrina by Xylander, this 

 differs in the colour of the thallus and of the apothecia, in the form of 

 the spores, and in the reaction of the hymenial gelatine. The thallus, 

 though determinate, is at times somewhat expanded, and varies in colour, 

 being paler in shady situations. The apothecia are numerous, with the 

 thalline margin occasionally at length obliterated. They are rarely the 



