PANNULAEIA.] LECANO-LECIDKEI. 343 



Allied to P. triptophylla, of which it has sometimes been considered as 

 a variety; but it is specifically distinct by the less developed thallus, the 

 type of the apotiiecia, and by the spores nut being definitely simple. The 

 thallus, which forms a crowdedly diffracto-areolate crust, at times sub- 

 ramuloso-divided, is normally determinate, and is very distinctly limited 

 by a broad, conspicuous liypothiillus. Occasionally it is of a dark-brownish 

 colour, as are also the apothecia, whence var. /3 fuscum (Hepp.J Mudd, 

 Man. /. c. The apothecia are numerous, scattered or approxiuiate, 

 sometimes becoming convex with evanescent margin. 



Hah. On calcareous rocks, mortar of walls and flint pebbles, in mari- 

 time, lowland, and upland tracts. — Distr. General and common through- 

 out Great Britain, and no doubt also in Ireland ; rarer in the Channel 

 Islands.— B. M. : Gorey, Island of Jersey. Shiere, Surrey; Glynde, 

 Sussex ; Shankliu, Isle of Wight ; Anstey's Cove, Torquay, and Paington, 

 S. Devon ; St. Minver, Cornwall ; near Cromford and liuxton, Derby- 

 shire ; near Stroud, Gloucestershire ; Bathani^ton Down<, Someraetshire ; 

 Llanymynech Ilill and Bridgenorth, Shropshire ; Barmouth, Merioneth- 

 shire ; Eglestone, Diu-ham ; Levens, Westmoreland; near Whitehaven, 

 Cumberland. Appin, Argyleshire ; Ben Lawers and Craig TuUoch, Blair 

 Athole, Perthshire ; Castleton of Braemar, Aberdeenshire ; Applecross, 

 lloss-shire. ^«'ear Belfast, co. Antrim. 



Subsp. P. psotina Cromb. Grevillea, xviii. (18S9) p. 44. — Thallus 

 as in the type. Apothecia internally pale ; spores occasionally 

 3-septate (the septa thin); hypotheeium almost entirely colourless 

 (or partly pale-brownish). — Pannaria nigra subsp. psjtiiui Xyl. ex 

 Cromb. Journ. Bot. 1873, p. 133. P. psotina Leight. Lich, Fl. ed. 3, 

 p. 156. Pannaria nigra var. psotina Ach. ,Jide Nyl. Lich. Scand. 

 (1861) p. 126. Lecotheciam nigrum Mudd, Man. p. 175 pro parte, 

 t. iii. f. Qb (middle fig.).— ^r;';!. Exs. : Mudd, n. 144. 



Difiers in the internal colour of the apothecia and in the spores being 

 rarely triseptate. In our specimens the thallus is subefTuse, with the 

 hypothallus rather narrow and at times little visible. In Flora, 1870, 

 p! 239, Ny lander seems inclined to regard it as a proper species. 



Hab. On mortar of walls and calcareous rocks in maritime and lowland 

 districts. — Distr. Only here and there in England and the Channel 

 Islands ; no doubt to be detected elsewhere. — B. M. : The Vale, Island 

 of Guernsey. Eastbourne, Sussex ; near the Horse, Windsor Great Park, 

 Berkshire ; Bilsdale, Yorkshire. Hexham, Northumberland ; "White- 

 haven, Cumberland. 



5. P. triseptata Xyl. ex Cromb. Grevillea, xviii. (1889) p. 44. — 

 Thallus subdeterminate, granuloso-crustaceous, diffracto-areolate, 

 brownish-black ; hypothallus blackish, not very distinct. Apo- 

 thecia lecideine, small, thinly margined, black or dark-reddish- 

 brown, internally whitish ; spores ellipsoid, 3-septate, 0,016-2-3 mm. 

 long, 0,006-9 mm. thick; hypotheeium blackish or brown; hyme- 

 nial gelatine bluish with iodine. — Pannaria nigra var. triseptata 

 Nyl. Lich. Scand. (1861) p. 126 ; Xot. Siillsk. pro F. et Fl. F. Forh. 

 v. p. 125 ; Cromb. Lich. Brit. p. 43, subsp. trisptata Xyl. ex Cromb. 

 Grevillea, i. p. 171. 



