ep 

 th 



PHYSCIA.] PHTSCIEI. 311 



rate, sessile, brownish-black, caesio-pruinose or naked, the thalline 

 margin entire or crenate ; spores 0,016-24 mm. long, 0,008-11 mm. 

 thick. Cromb. Grevillea, xv. p. 78. Parmelia stellaris Hook. El. 

 Scot. ii. p. 55 pro parte ; Sm. Eng. El. v. p. 201 pro parte. Lichen 

 stellaris Linn. Sp. PL (1753) p. 1144 ; Ach. Prodr. p. 111. Borrera 

 okscura /3. chloantha (non Ach.) Mudd, Man. p. 110. Physcia retro- 

 gressa Stirt. Trans. Glasg. Soc. Nat. 1875, p. 85 vix differt. As 

 observed by Acharius (Meth. p. 209) the synonymy was then (as it 

 still is) for the most part doubtful. It is, however, the plant of 

 Linnaeus according to specimens in his herbarium. Brit. Exs.: 

 Mudd, n. 81. 



Distinguished from P. pulverulentd and its varieties by the smaller, 

 ruinose thallus, which does not become greenish when moist, and by 

 the smaller spores. It has been almost always confounded with the fol- 

 lowing species, and especially with its var. /3. The apothecia are nume- 

 rous, chiefly central, with the margin often nexuose. The spermogones 

 are not uufrequent, with spermatia equally cylindrical, 0,0045 mm. long, 

 scarcely 0,001 mm. thick. It is a variable plant, presenting the varieties 

 aud subspecies to be described. 



Hob. On the trunks and branches of trees by roadsides, and in avenues 

 of lowland and upland tracts. Distr. Seen only from a very few localities 

 in N. England and the Grampians, Scotland ; no doubt overlooked else- 

 where. B. M. : Near Ayton, Cleveland, Yorkshire. Finlarig, Killin, 

 Perthshire ; Monaltrie House, Ballater, Aberdeenshire. 



Var. (3. leptalea Nyl. Syn. i. (1860) p. 425. Thallus narrowly 

 laciniate ; laciniae discrete, appresscd, fibrilloso-ciliate at the margins, 

 the cilia whitish or brownish ; otherwise as in the type. Cromb. 

 Lich. Brit. p. 39 ; Leight. Lich. El. p. 151, ed. 3, p. 140. Lichen 

 leptaleas Ach. Prodr. (^1798) p. 108. Borrera Tiispida Mudd, Man. 

 p. 106. Lichenoides hispidum minus et tenerius, scutellis nigris Dill. 

 Muse. t. 20. f. 46, A, B, D. 



Differs in the narrower, more discrete, and marginally ciliate lacinise. 

 It must not be confounded, as has sometimes been done, with less forni- 

 cate states of the following subspecies. The apothecia, which are not 

 unfrequent, vary similarly to those of the type. 



Hub. On the trunks of trees, rarely on rocks, in lowland and upland 

 districts. Distr. Occurs only here and there throughout England, in 

 N. Wales, S. W. and Central Scotland ; rare in Ireland. B. M. : St. 

 Leonard's Forest, Sussex ; Lymington, Hants ; Brading, Isle of Wight ; 

 Bolt Head, S. Devon ; near Penzance, Cornwall ; Oswestry, Shropshire ; 

 Aberdovey, Merionethshire ; Island of Anglesea ; near Gainsford, Dur- 

 ham. Near Edinburgh ; Appin, Argyleshire ; Killin and Blairdrummond, 

 Perthshire ; Auchterhouse, Forfarshire ; Cults, near Aberdeen. Carri- 

 galoe, Cork Harbour. 



Var. y. subobscura Nyl. Sallsk. E. et El. Eenn. Forh. ir. 

 (1859) p. 239 ; Syn. i. p. 426. Thallus greyish or greyish-brown, 

 beneath white with scarcely any rhizinae ; laciniae short, narrow, 

 the marginal cilia blackish or dark ; otherwise as in the preceding 



