PTERYGIUM.] 



35 



at the circumference, subcoralloideo-multifid or microphylline and 

 usually diffracto-globulose in the centre, dark-olive or olive-brownish- 

 black, opaque ; laciniae thin, plane, multifid, imbricately crowded, 

 obsoletely rugulose. Apothecia small, plane or slightly convex, 

 black ; spores ellipsoid, 3-septate, 0,015-20 mm. long, 0,006-8 mm. 

 thick ; hymenial gelatine deep blue with iodine. Cromb. Gre- 

 villea, v. p. 108 ; Leight. Lich. JF1. ed. 3, p. 12. 



This is externally somewhat like Pannaria triseptata Nyl., hut differs 

 in the absence of a hypothallus, and in the laciniae being radiate at the 

 circumference and usually digitate at the apices ; the spores also are 

 somewhat smaller. In the only fertile British specimen seen the apo- 

 thecia are sparingly present. 



Hob. On schistose rocks in alpine situations. Distr. Very local and 

 scarce amongst the S. Grampians, Scotland. B. M. : Summit of Craig 

 Calliach, Perthshire. 



3. P. Lismorense Cromb. Grevillea, v. (1877) p. 108. Thallus 

 thin, subfurfuraceous, thinly or obsoletely radiate, adnate, variously 

 confluent, blackish or olive-black. Apothecia small, thinly mar- 

 gined, black, dark within; spores oviform, 1-scptate, 0,010-0,011 

 mm. long, 0,005-0,006 mm. thick ; epithccium bluish-black ; hypo- 

 thecium cellular, and (with the perithecium) violet-blackish ; hyme- 

 nial gelatine bluish, then dark-yellowish with iodine. Nyl. Flora, 

 1877, p. 221; Leight. Lich. Fl. ed. 3, p. 12. Brit. Exs: Cromb. 

 11. 101. 



The thallus spreads rather extensively, though not continuously, over 

 the substratum. In its younger state the radii are more discrete at the 

 circumference. It is allied to P. asperellum Nyl., from which it differs 

 in the thallus and the smaller spores. 



Hab. On calcareous rocks in maritime tracts. Distr. Local and scarce 

 in the S.W. Highlands. B. M. : Island of Lismore, Argyleshire. 



11. LEPTOGIDIUM 



Nyl. Flora, 1873, p. 195 

 (cfr. Cromb. Grevillea, v. 

 p. 76). Thallus minute, 

 fruticulose, branched, 

 somewhat fragile ; goni- 

 mia moniliform ; cortical 

 layer cellular, distinct. 

 Apothecia subbiatorine ; 

 spores 8nae, ellipsoid, 

 simple, colourless ; hyme- 



Fig. 7. 



nial gelatine bluish with LeptogWum dcndriscum Nyl.-a Thalline 

 n- o , branch and branchlet, X oO. b. Transverse 



iodine. Spermogones not section of a branch / x 2oa c- Apex of a 



bifurcate branchlet, showing the moniliform 

 chains of the gouiinia, X 200. d. Two 

 series of gonimia, X 350. 



seen rightly developed. 



This genus, recently in- 

 stituted by Nylander, is 



