124 LECANO-LECIDBEI [bIATORINA 



Lecidca pulverea Borr. in Engl. Bot. Suppl. t. 2726 (18.'U) ; 

 Hook, in Sm. Engl. FL p. 181; Tayl. in Mackay Fl. Hib. ii. 

 p. 126 ; Cromb. Lich. Brit. p. 89 ; Leight. Lich. Fl. p. 322 ; ed. 

 3, p. 334. 



Exsicc. Bohl. n. 90; Cromb. n. 187; Larb. Licb. Hb. n. 150. 



Besembles B. Liglitfootii var. commutata, but is easily dis- 

 tinguished by the larger spores. The apothecia are, according tO' 

 Nylander (Flora li. p. 347), at times pale-flesh-coloured, which is not 

 the case in the British specimens. 



Hab. On trunks of old trees generally near the roots, rarely 

 incrusting mosses on rocks in maritime and mountainous districts. — 

 Distr. Somewhat local, though usually plentiful where it occurs 

 throughout the British Isles. — B. M. Withiel, Cornwall ; near Torquay 

 and Lustleigh, Devon ; New Forest, Hants ; Ardingly and St.. 

 Leonard's Forest, Sussex ; Capel Cym and Barmouth, Merioneth ;. 

 Maltby Wood, Yorkshire ; Windermere, Westmoreland ; Keswick^. 

 Cumberland ; Falls of Clyde, Lanark ; Barcaldine, Argyll ; Glen 

 Falloch, Glen Lochay and Aberfeldy, Perthshire ; Glengariff, Cork ;. 

 Mangerton, Muckruss, Dromore and Turk Mt., Kerry ; Addergoole, 

 near Kylemore, Glendalough and Doughruagh Mt., Galway. 



25. B. Lightfootii Mudd Man. p. 179 (1861).— Thallus 

 determinate or subeffuse, thickish, granulose-verrucose, greenish- 

 white or greenish-grey (K — , CaCl — ). Apothecia moderate, 

 subinnate-sessile, plane or rather convex, slightly shining, dark- 

 brown or black, margined, the margin thin, smooth, entire or 

 flexuose, paler ; paraphyses concrete, brown at the apices ; hypo- 

 thecium pale-greyish ; spores ellipsoid, faintly 1 -septate, constricted 

 in the middle. — Lichen Liglitfootii Sm. Engl. Bot. t. 1451 (1805). 

 Lecidea Liglitfootii Ach. Lich. Univ. p. 177 (1810) ; S. F. Gray 

 Nat. Arr. i. p. 469 ; Hook, in Sm. Engl. Fl. v. p. 180 ; Cromb. 

 Lich. Brit. p. 65 ; Leight. Lich. Fl. p. 319 ; ed. 3, p. 333. 



Exsicc. Larb. Lich. Hb. n. 106. 



Somewhat similar in habit and appearance to L. parasema. The 

 innate apothecia occasionally seem as if crowned by the thalline 

 granules, which, in conjunction with their paler margin, suggests ft 

 Lecanora ; there are, however, no traces of a true thalline margin. 

 In some habitats (e.g. firs) the thallus is much thinner with the 

 granules more scattered and the apothecia smaller. The spermogones 

 are small and brown ; the spermatia subglobose and very minute 

 0,002 mm. long, 0,0015 mm. thick. 



Hab. On the smooth trunks of trees, chiefly birch, rarely fir, in 

 upland wooded districts. — Distr. Not unfrequent in England, Wales,, 

 and S. Ireland. — B. M. Eeigate Hill, Surrey ; St. Leonard's Forest^ 

 Ardingly Rocks, near Parham, near Petworth, near Eastham,. 

 Cuckfield, Hayward's Heath and Wiggonbolt Common, Sussex ; 

 Lyndhurst, New Forest, Hants ; Ullacombe, Dartmoor, Devon ; 

 Lewknor, Oxfordshire ; near Raider Du, Radnorshire ; Dolymelynen 

 and Nannau, Dolgelly, Merioneth ; Baysdale, Cleveland, Yorkshire ; 

 Riverstown, Cork ; Dunkerron, Kerry. 



Yar. /3 commutata Mudd /. c. — Thallus granulose-leprose or 

 subpulverulent, greenish-grey. Apothecia as in the type. — Leca- 



