Rev. W. A. Leighton on the Lichens of Cader Idris. 201 



Stenhammer, Licli. Siiec. 85 ; Th. M. Fries, Lich, ; and from 

 " Dunkerron, Ireland, Dr. Taylor." It is also given in Anzi, 

 Lich. Ital. Sup. 30, M. & N. 947, and Korb. L. Sel. Germ. 

 271. The Rev. John Harriman's specimen from Teesdale, 

 in herb. Borrer., mentioned in E. Bot. Suppl., most nearly 

 resembles the figures in that work, but was in too old and 

 imperfect a condition to allow of the sight of the spores, which 

 are cylindraceo-fusiform, 3-7-septate. 



I suspect that, in my Lich. Brit. Exs. 383, 1 have distri- 

 buted both plants, S. cereolinum and Pilophoron fibula^ as I 

 have gathered both about Llyn Aran ; but microscopical exa- , 

 mination will rectify this, the spores of Pilophoron fibula being 

 elliptical and simple. The granules of the thallus are also 

 much more flattened and squamaceous. So far as my expe- 

 rience goes, 8. cereolinum affects the horizontal surfaces of 

 boulders, whilst Pilophoron fibula grows on the perpendicular 

 faces of wet rocks. I believe also that I gathered Pilophoron 

 fibula in Cwm Glas, Snowdon, in 1865, a single specimen only, 

 which, unfortunately, I have lost. 



It may be useful perhaps to remark that in Lecidea con- 

 tigua, Ach., and L. confluens, Ach., the apothecia arise from 

 the thallus, in L. petrcea, Flot., and L.fusco-atra^ Ach., from 

 the hypothallus. L. contigua has the disk of the apothecia 

 pruinose, either white or, when old, of a rusty brown, and is 

 always, when seen under a lens, roughened by the prominent 

 apices of the paraphyses. The margin is very thick and ob- 

 tuse, the lamina proligera reclines on an enormously thick 

 black or blackish-brown cupular excipulum, and the spores 

 are oval or oblong, and very large. L. confiuens is at once 

 known by the very blacky smooth, velvety appearance of the 

 disk, which is altogether destitute of white pruina. The ex- 

 cipulum is somewhat similar to that of contigua ; but the spores 

 are scarcely half the size. L. petrcea has the thallus in verru- 

 cose areolas, and the spores oblong and of a muriform character, 

 with horizontal and perpendicular septa. L. fusco-atra, again, 

 is well marked by the areolae of the thallus being shining 

 on \\iQ,\x plane or flattened surface, and the edges of each areola 

 raised up into a very thin sharp margin. The spores are 

 similar in shape and size to those of L. confiuens. 



Lecidea plicatilis, Leight., n. sp. 



Thallus sordide albidus, minute plicato-verrucoso-granulosus, 

 areolato-diffractus, hypothallo fusco ; apothecia majuscula, 

 undulato-plana, nigro-fusca, arete adnata, connato-deformia, 

 margine obtuso undulato jetate plus minusve attenuato 

 aut obliterato ; sporge 4-8, incolores, elongato-ellipsoidese, 

 3-4-5-septat£e, constrictas, murali-divisas ; hypothecium 



