LECANIA | LECANORACEX 345 
9. L. prosechoides Oliv. Exp. Syst. Lich. Fr. i. p. 311 
(1897).—Thallus thin or thickish in places, unequally or warted- 
areolate, whitish or dull-yellowish (K —, CaCl —). Apothecia 
rather small, plane, somewhat prominent, the disc brown, 
becoming black, the thalline margin subentire, partly dis- 
appearing; paraphyses somewhat concrete, thickish, septate, 
enlarged and brown at the tips; spores ellipsoid, simple, 
becoming 1-septate, 9-17 p long, 4—6 w thick.— Lecanora helicopis 
f. dilutior Nyl. Lich. Scand. p. 159 (1861); Carroll in Journ. 
Bot. iv. p. 25 (1866); Cromb. Lich. Brit. p. 50. DL. umbrina 
subsp. prosechoides Nyl. ex Cromb. Lich. Brit. p. 51 (1870) ; 
f. prosechoides Leight. Lich. Fl. p. 208 (1871); ed. 3, p. 191. 
L. prosechoides Ny. in Flora lv. p. 250 (1872) (inel. f. sublutior 
op. cit. lxv. p. 456 (i882)); Cromb. in Grevillea i. p. 82 & 
Monogr. i. p. 426 (incl. f. sublutior). L. prosecha Leight. Lich. 
Fl. ed. 3, p. 224 (1879) (non Ach.). 
Kesicc. Cromb. n. 67; Larb. Lich. Hb. n. 94. 
A maritime plant, differing from L. erysibe in the stouter thallus 
and in the generally thicker spores. In the British specimens they 
measure usually about 8-12 » in length, the size given by Crombie. 
The thallus may be determinate and the apothecia are frequently the 
host of Arthonia varians. In some specimens the hymenium in the 
upper part is bluish-green. Sometimes the apothecia are lighter in 
colour (f. swblutior). 
Hab. On schistose, rarely on cretaceous rocks or cement in mari- 
time districts.—Distr. Fairly general round the coasts of the British 
Isles—B. M. Noirmont, Jersey; Vale Bay, Guernsey; Penzance, 
Cornwall; between Porlock and Lynton, Devon; Manorbeer, Tenby, 
Pembrokeshire; Southerndown, Glamorganshire; The Mowddach 
and Dolgelly, Merioneth; Pwlheli, Carnarvonshire; Port Soderick, 
I. of Man; Barcaldine and Loch Creran, Argyll; Portlethen, Kin- 
cardineshire; Unst, Shetland; Kilkee, Clare; Letterfrack, Conne- 
mara, Galway; Ardglass, Down. 
Var. melacarpoides Oliv. tom. cit. p. 312.—Thallus bluish- 
white. Apothecia black or bluish-black.—Lecanora prosechoides 
subsp. melacarpoides Nyl. in Flora Ixiv. p. 7 (1881); var. mela- 
carpoides Knowles in Sci. Proc. Roy. Dubl. Soc. xiv. p. 129 
(1913). Specimen not seen. 
Hab. On rocks by the shore. Collected on top of the sea-wall at 
Sutton, Howth, Dublin, by M. C. Knowles. 
Var eruginascens (errore xruginosa) Oliv. 1. c.—Thallus 
leaden-white, limited by an eruginous dendritic hypothallus, also 
visible between the areole —Lecanora prosechoides var. #ru- 
ginascens Wedd, in Mém. Soc. Sci. Nat. Cherb. xix. p. 273 
(1875); Knowles l. ¢. (errore wruginosa). Specimen not seen. 
Hab. On quartz rocks by the shore. Collected near Needles at 
Howth, Dublin, by M. C. Knowles. 
