1--1 LICHENACEr. [PYCNOTKEMA. 



As limited, this is a very natural tribe, readily known bv the form ol" 

 the thallus and the character of the variously coloured, but liever normallv 

 black, apothecia. The five genera of which it is composed, as constituted 

 by Xylander (two of which, viz. Heterodm and Cladi<t, are exotic), while 

 closely related to each other, are separated by the basal thallus and the 

 podetia. The species are for the most part very social in Jiabit. 



31. PYCNOTHELIA 



Daf. Bory Ann. Sc. Phys. 

 (1821) viii. p. 45; Ach. 

 Lich. (1810) p. 571 (ut 

 sectio Cenomyces). — 

 Thallus crustaceoiis at 

 the ' base, persistent ; 

 podetia papillaeform , 



simple or branched, cor- 

 ticate, glabrous. Apo- 

 thecia small, terminal on 

 the podetia ; spores 8na3, 

 obloug, simple, colour- 

 less ; theca3. especially 

 the apices, bluish with 

 iodine. Spermogones 



normally terminal on the 

 podetia, conical ; sper- 

 matia cylindrical, and 

 somewhat acute at either 

 apex, or slightly arcuate. 



Fig. 34. 

 Ptjenofhelia papillaria Duf. — a. Sections of 

 apothecia, X30. b. A theca and pai-apbysis, 

 X350. c. Spores, x500. d. Section of a 

 spermogone. X 30. e. Sterigraata and sper- 

 matia, x500. 



Though usually regarded as a section, or at most a subgenus of Cla- 

 donia, this seems a distinct genus characterized by the crustaceous thallus 

 and papillate podetia. The texture of the thallus is entirely that of 

 Cladonia {vide Nyl. Syn. i. pp. 188, 189). 



1. P. papillaria Duf. Bory Ann. Sc. Phys. (1821) viii. p. 46.— 

 Thallus granulose at the base, forming a more or less effuse crust, 

 whitish or pale yellow-greyish ; podetia short, clavato-cylindrical or 

 cylindrical, very fragile, egranulose, simple or subsimple, white or 

 glaucous (K-|- yellowish, CaCl — ). Apothecia at first somewhat plane 

 and marginal, at length convex, solitary or aggregate, brown or 

 reddish-brown; spores 0,000-0,014 mm. long, 0,0045 mm. thick. — 

 Sm. Eng. Fl. v. p. 241 ; Gray, Nat. Arr. i. p. 424 ; Cromb. Lich. Brit, 

 p. 18 ; Leight. Licb. Fl. p. 55, ed. 3, p. 52. — Cladonia papillaria 

 ^ludd, Man. p. 52 ; Brit. Clad. p. 34. Cenomyce papillaria Tayl. in 

 Mack, Fl. Hib. ii. p. 82. Lichen papillaria Ehrh. Phyt. (1780) 

 n. 100 ; Dicks. Crypt, fasc. i. p. 13 ; With, Arr. ed. 3, iv. p. 45 ; 

 Eng. Bot. t. 907. Coralloides minimum fragile, Aladrqwrce instar 

 nascens Dill. Muse. 107, t. 10. f. 28.— Brit. E.vs. : Leight. n. 208 ; 

 Mudd, n. 22, Clad. n. 80 ; Cromb. n. 121. 



The thallus in more barren liabitats is somewhat determinate, and 

 the podetia are often subverruca'form, usually somewhat scattered, though 



