316 LICKENACEI. [PHTSCIA. 



Hub. On tlie p;vooth bark of a younpf tree in a maritime district. — 

 Distr. Extremely local aud rare, in S. England. —B. M, : Near Ryde, 

 Isle of Wight. 



18. P. erosa Leight. Lich. Fl. (1871) p. 152.— Thallus subor- 

 bicular, moderate, shortly laciniate, greyish or glaucous-whito ; 

 beneath m hitish, sparingly fibrilloso-rhiziuose ; laciniae crowdedly 

 imbricate, more or less ascending, rounded and eroso-laeerate or at 



length pulverulent at the apices (K^yellow, CaCl[|]yellow). Apo- 



thecia moderate, brownish-black, the thalline margin subentire ; 

 spores oblong, 0,0 1-1—20 mm. long, 0,007-10 mm. thick. — Cromb. 

 Journ. Bot. 1S72, p. 358 ; Leight. Lich. Fl. ed. 3, p. 139.— Par- 

 meJia erosa Borr. Eng. Bot. Suppl. 1837, t. 2807. Borrera ccesia 

 y. albiiiea (nou Ach.) Mudd, Man. p. 108, t. ii. f. 31 ; Cromb. 

 Lich, Brit. p. 39. Squamavla tribacia Sm. Eng. Fl. ii. p. 194 pro 

 parte. — Brit. Exs. : Leight. n. 2(36; Larb. Caesar, n. 24; Lich. Hb. 

 u. 294. 



A well-marked species somewhat resembling P. trihaeia, from which 

 it is well distinguished by the efariuose and esorediate thallus, the apices 

 of the lacinipe, and the different chemical reactions. The apotliecia, 

 which with us are extremely rare, are chiefly central, numerous, with the 

 thalline margin at length subcrenate. 



Hab. On trees, walls, and rocks in maritime and upland districts. — 

 Distr. Not very general nor common throughout England and in the 

 Channel Islands ; rare in S. Scotland, the S.W. Highlands and S. Gram- 

 pians ; not yet seen in Ireland. — B. M. : Rozel, St. Ouen's, and La Moye, 

 Island of Jersey ; Jerbourg and Moulin Huet, Island of Guernsey. Bex- 

 hill aud Hurstpierpoint, Sussex ; Porchester, Hants ; Plymouth and 

 Wembury, S. Devon ; near Penzance and Withiel, Cornwall ; St. Mary's, 

 Scilly ; near Swindon, Wilts ; Malvern, Woi'cestershire ; Nannau, Dol- 

 geUy, Barmouth, and Aberdovey, Merionethshire ; near Ayton, Cleve- 

 land, Yorkshire ; near Staveley, Westmoreland. New Galloway, Kirk- 

 cudbrightshire ; Barcaldine, Argyleshire ; Ben Lawers, Perthshire. 



19. P. astroidea Nyl. Act. See. Linn. Bord. se'r. 3, i. (1856) 

 p. 308. — ThaUus orbicular, thin, closely adpressed, granulosa or 

 leprose in the centre, laciniato-efRgurate at the circumference, 

 greyish-white ; beneath whitish, black fibriUoso-rhizinose ; laciniae 



narrow, contiguous (K^TyeUow, CaCl . yeUow). Apothecia innato- 



sessile, small, concave or plane, brownish-blackish, naked or prui- 

 nose, the thalline margin inflexed, crenulate ; spores ellipsoideo- 

 oblong, 0,017-26 mm. long, 0,008-11 mm. thick.— Cromb. Lich. 

 Brit. p. 39; Leight. Lich. Fl. p. 153, ed. 3, p. 139.— Borrera 

 astroidea et /3. dementi Mudd, Man. p. 108, t. ii. f. 32. Parmelia 

 astroidea Clem. Ens. Add. (1807) p. 302. Squamaria dementi 

 Sm. Eng. Fl. V. p. 196. Parmelia Clementi Turn. Trans. Linn. Soc. 

 ix. p. 146, t. 13. f. 1 ; Gray, Nat. Arr. i. p. 439 ; Tayl. in Mack. 

 Fl. Hib. ii. p. 147. Lichen Clementi Eng. Bot. t. 1779. — Parnwlia 



