440 THALLOPHY.TES 



Var. a. stettarirexpama, Fr. thallus stellate-expanded, fibres shorter. 



Var. b. tribracia, Fr. lobes squamulose, ascendant, sparingly fibrillose, the 

 apices pulverulent. 

 Hob. Roots, rocks, Ac., among mosses : frequent. 



22. P. pliaea, Tuckerm. MS. [Fuscous] : Thallus subcartila- 

 gineous, naked, glaucous-white; beneath whitish and sparingly 

 ciliate with short black fibres ; laciniae linear, many-cleft ; apothe- 

 cia appressed ; disk convex, naked, a little shining, rufous-fuscous ; 

 margin not elevated, at length granulated. 



Hab. On quartz rock : very rare. 



Obs. The species is established on a single plant. Should more 

 perfect specimens be obtained, they may render some modification 

 of the characters necessary. 



23. P. Obscftra, ,Fr. [Obscure]: Thallus submembranaceous, 

 greenish, becoming livid-fuscous when dry ; under side black and 

 fibrillose; lobes sublinear, incised-multifid, often sorediiferous, or 

 the margins pulverulent ; apotheeia sessile, very entire, naked, black- 

 fuscous. 



Var. b. ulotiirix, Fr. lobes linear, sub-cfliate; apotheeia fibrillose beneath. 

 Sab. Trunks of trees ; dead wood, &c. : frequent. 



24. P. fibrdsa, Fr. [Fibrous] : Thallus suborbiculate, the lacer- 

 ate laciniae concrete and subcrustaceous at the centre, those of the 

 circumference flat, from green becoming more or less yellow, be- 

 neath cinereous-fibrous ; apotheeia crowded, vey entire, orange, 

 fibrose-radiate beneath. 



Var. b. stdlata, Tuckerm. MS. laciniae discrete, stellate. 

 Sab. On shrubbery, and the branches of small trees. 

 Obs. We have only the var. b. here. 



SECTION" 2. 



ThaUux subfoliaceous, st length subgranular, arising from a fifcrfllose hypo- 

 tlsallufl, which is adnate to th matrix. 



SUBSECTION Z. PYX'IKE. 



Apothetia erunrpent, closed, palish, becoming patellaeform, and, witli tie altered! 

 thallfoe margin, black; finally cephaloid, excluding the margin. 



25. P. MOrediata, Tuckerm. [Sorediate]: Thallus swbcrusta- 

 ceous-foliaceous, laciniate-multifid, green becoming glaueescent and 

 cinerascent; under side black, with crowded greenish-nigrescent 

 fibres ; lobes linear, channelled, incised, obtuse, imbricate and con- 

 crete at the centre, often sorediiferous ; apotheeia at first pale, and 

 concave, becoming black, convex, finally proliferous-papillate and 

 irregular. 



Hab. Trunks, and rocks. Often sterile. 



Obs. A variable species ; but not presenting any well-marked 

 varieties. 



SUBSECTION 4. AMPHILO^MA. 



Apotheeia erumpent, subcoronate, with an accessory thalline margin ; disk waxy, 

 thickish, naked ; thallus foliaceous, submonophyllous, rounded, becoming crus ta- 

 ceous at the centre; hypothallus spongy-pannose. 



