332 PYRKNOCARPKI [mICROTHELIA 



1-sepiate constricted, brown 0,025-35 mm. long, 0,010-12 iimi. 

 thick. 



Apt to bo confused with Artlwjyijrruia saxicola on account of the 

 minute shining perithecia. The specimens in the British Museum 

 were collected by W. Joshua and labelled by him A. aaxicola var. 



Hah. On calcareous rocks. — Distr. Rare in W. England. — 

 B. M. Sapperton, Gloucestershire. 



4. M. exerrans A. L. Sm. — Thallus thin, blackish, scattered. 

 Perithecia minute, black ; perithecial wall entire ; spores 8 in 

 the ascus, blackish, oblong, 1 -septate, 0,010-15 mm. long, 

 0,003-5 mm. thick ; hymenial gelatine wine-red with iodine. — 

 Endococcus exerrans Nyl. in Flora Ixii. p. 360 (1879) ; Cromb. in 

 Grevillea viii. p. 114 (1880). Specimen not seen. 



Distinguished by the narrow spores. Nylander notes the rather 

 thick colourless chroolepoid gonidia with cells 0,018-23 mm. thick. 



Hab. On quartzose stones, Ben-y-Gloe, Blair Athole, Perthshire. 



5. M. dissepta A. L. Sm. — Thallus whitish-grey, sometimes 

 faintly yellowish, tartareous, thin, slightly cracked-areolate, sub- 

 determinate. Perithecia black, numerous, somewhat prominent, 

 the upper part convex, the ostiole a minute pore ; perithecial 

 wall entire, paraphyses indistinct ; spores 8 in the ascus, ellipsoid, 

 brown, 3-septate, 0,018-22 mm. long, 0,007-010 mm. thick ; 

 hymenial gelatine not tinged with iodine. — Verrucaria dissepta 

 Nyl. in Flora lix. p. 576 (1876) ; Cromb. in Grevillea v. p. 107 ; 

 Leight. Lich. Fl. ed. 3, p. 480. Specimen not seen. 



Nylander {I. c.) suggests that possibly the perithecia may be 

 parasitic on the thallus of some other lichen. 



Hab. On mica-schist rocks, Doughruagh Mts., Connemara, Galway 

 (the only locality). 



116. PORINA Ach. Lich. Univ. p. 60 (1810) pro parte; 

 emend. Muell.-Arg. in Flora Ixvi. p. 320 (1883). — Segestrella Fr. 

 Lich. Eur. p. 460 (1831) {Segestria torn. cit. p. 429) ; Mudd Man. 

 p. 283. (PL 52.) 



Thallus variously crustaceous, not corticated, sometimes 

 developed within the substratum. Perithecia simple, superficial 

 or semi-immersed ; perithecial wall light-coloured, becoming 

 darker towards the ostiole, entirely dark-coloured or dimidiate ; 

 paraphyses persistent, simple ; asci elongate, 6-8-spored ; spores 

 elongate-fusiform or clavate, colourless, 2- multi-septate. Sper- 

 mogones small, globose with simple or branched sterigmata and 

 rod-like or elongate-fusiform spermatia. 



Distinguished from Arthojpyrenia by the character of the para- 

 physes. The texture of the perithecial wall is also more variable ; it 

 is usually softer in texture, and in some species waxy and light- 

 coloured {Segestrella). 



