rHLYCTlS,] LKCAXO-IJ;CIDEi:i. 513 



brook, Isle of "Wight; New Forest, Hants; Ilsham Walk, Torqiiaj', 

 S. Devon ; Batliampton Downs, Somersetshire ; Cirencester, fJloueester- 

 sliire ; Ilarboro' Magna, Warwiek.-liire ; Ilnglith, near C'hnrch 8tretton, 

 and O.sAve.stry, Shropshire: Djirnu/nth and Aberdovey. jNlerionethsliire; 

 Airyliolme AVood and Hoggart's AN'ood, Cleveland, Yorksliire. Kits- 

 boro', lliverstone and Castlehernard Park, to. Cork ; Dunkerron, 

 Killarnej, co. Kerry. 



2. P. argena Koerb. Syst. Lich. Germ. (Is55) p. 391.— Thallus 

 effuse, thin, smoothish or rugose, pulverulent, silvery-grey or 

 cream-coloured (K + yellow, then deep rod). Apothccia minute, 

 brownish-black, Ctesio-sufl'used ; spores solitary, oblong or cylindrico- 

 oblong. very large, 0,100-0,140 mm. long, 0,027-50 mm. thick. — 

 Miidd, Man. p. 280; Cromb. Lich. Brit. p. 61 ; Leight. Lich. Fl. 

 p. 246, ed. 3, p. 237. — Vuriolaria arrjena Turn. & Eorr. Lich. 

 Brit. p. 75; Sm. Fng. Fl. v. p. 171. Lichen ar(/enus Ach. Prodr. 

 (1798) p. 8 ; Eng. Bot. t. 1923. 



Subsimilar to the preceding, from which it at once differs in the non- 

 apiculate spores. It usually occurs only in a sterile condition, when it 

 is verv apt to be overlooked. The apothecia are either scattered or 

 aggregate, and in the former case are with difficulty detected by the 

 naked eye. 



JIab. On the trunks of old trees in upland tiacts. — Uistr. Local (at 

 leas't in fruit) in S. and W. England. — B. M. : Epping Forest, Essex ; 

 Ightham, Kent; New Forest, Hants; Hasleniere, Surrey ; Beckey Falls, 

 S. Devon ; Burnham Beeches, Bucks ; Charnwood Forest, Leicester- 

 shire ; Barmouth, Merionethshire ; Oswestry, Shropshire. 



65. THELOTREMA Ach. Meth. (1803) p. 130 pro parte; ^'yl. 

 Mem. Soc, Cherb. t. iii. (1855) p. 324. — Thallus thinly crustaceous, 

 continuous, containing chrysogonidia. Apothecia verruca?f'orm, at 

 first closed, then open, with a proper and a thalline margin ; spores 

 variable in number (l-4n8e or 8n8e), oblong or fusiform, usually 

 colourless ; paraphyses slender ; hymenial gelatine not tinged with 

 iodine. Spermogones with simple sterigmata and short straight 

 spermatia. 



A genus well characterized by the fructification. Nearly all the 

 species are exotic and natives of warm regions. The three which occur 

 in Europe, one of which is confined to our Islands, belong to the sub- 

 genus Euthehtrema Nyl. 



1. T. lepadinum Ach. Meth. (1803) p. 132 pro parte: Syn. 

 p. 115. — Thallus subeffuse or rarely determinate, thin, smooth or 

 slightly rnguloso-unequal, protuberant around the apothecia, whitish 

 or cream-coloured (K + red, CaCl— ), Apothecia submoderate,urceo- 

 lato-scutelliform, dark-brown or blackish, csesio-pruinose or naked ; 

 the proper margin lacerate, inflexed, the thalline margin thin, even ; 

 spores (4nge) 8nse, oblongo-fusiform, colourless, 0,035-70 mm. 

 long, 0,011-16 mm. thick. — Leight. Angio. Lich. p. 31, t. 12. f. 1; 

 Lich. Fl. p. 247, ed. 3, p. 238 ; Cromb. Lich. Brit. p. 61 ; Mudd, 

 Man. p. 278, t. 5. f. 116; Turn. & Borr. Lich. Brit. p. 180; Sm. 

 Eng. Fl. V. p. 101 ; Grav, Nat. Arr. i. p. 494 ; Hook. Fl. Scot. ii. 



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