LECANORA.] LECANO-LTlClnEEr. IJol 



Cliaractciizcd by tlie type of the tliallus, whicli is comparable witli 

 tliat of PdniicUoims, and by the structure of tlie sperniogones, which are 

 iiuniersed, their ostioles being concoloroua with the thallus. 



Fig. 50. 



Lecanora {Squamaria) crassa Ach. — a. A theca and parapbjsis, x350. 

 b. Two spores, X 500. c. Sterigmata and spermatia, x 500. 



2. L. crassa Ach. Lich. Univ. (1810) p. 413.— Thallus indeter- 

 minate or suborbicular, subcartilaginoiis, loosely adpressed, thick, 

 squamoso-imbricate, pale-livid or pale-yellowish ; squamules some- 

 what depressed, roundly lobato-crenate (K — ). Apothecia mode- 

 rate, sessile, plane or somewhat convex, reddish-brown, the thalline 

 margin entire, at length excluded ; spores ellipsoid or oblongo-ellip- 

 soid, 0,011-14 mm. long, 0,005-6 mm. thick. — Cromb. Grevillea, 

 xviii. p. 44 ; Hook. Fl. Scot. ii. p. 51. — Squamarla crassa Sm. Eng. 

 Fl. V. p. 193; Mudd, Man. p. 127; Cromb. Lich. Brit. p. 44; 

 Leight. Lich. FL p. 171, ed. 3, p. 157. Psoroma crassum Gray, jS'at. 

 Arr. i. p. 444. Lichen cmssus Huds. Fl. Angl. ed. 2 (1778), p. 530 ; 

 Eng. Bot. t. 1893. Lichen cartiJagineus Lightf. Fl. Scot. ii. p. 815 ; 

 With. Arr. iv. p. 29. Lichenoides cartilagineum, scutellis fulvis 

 2)1anis Dill. Muse. 179, t. 24. f. 74.— Brit. Exs. : Leight. n. 5 ; Larb. 

 Caesar, n. 73 ; Lich. Hb. n. 333 ; Cromb. n. 157 ; Bohl. n. 2 ; 

 Dicks. Hort. Sic. n.24. 



The largest British species of the subgenus, with the thallus usually 

 very much expanded, rarely smaller and somewhat orbicular, often here 

 and there whitish. "With us it is much less variable than it is in warmer 

 regions, presenting only the following form. It is usually well fertile, the 

 apothecia becoming rather large in age. 



Hab. On the ground and on rocks, chiefly calcareous, in maritime and 

 upland districts. —Distr. General and common in England and Wales • 

 rarer in Scotland, Ireland, and the Channel Islands. — B. M. : Quenvais, 

 Island of Jersey ; Islands of Herm and Guernsey. Hm-stpierpoint, 

 Sussex ; Berry Head, S. Devon ; St. Merryn, Cornwall ; Cleeve Hhl and 

 Cheddar Cliffs, Somersetshire ; St. Vincent's Rocks, Bristol, Gloucester- 

 shire ; PontEynon, Glamorganshire ; near Tenby, Pembrokeshire ; Aber- 

 dovey, Merionethshire ; Snowdon and Great O'rme's Head, Carnarvon- 



