124 LICHENACEL. [PYCNOTHELIA. 
As limited, this is a very natural tribe, readily known by the form of 
the thallus and the character of the variously coloured, but never normally 
black, apothecia. The five genera of which it is composed, as constituted 
by Nylander (two of which, viz. Heterodea and Cladia, ave 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 habit. 
31. PYCNOTHELIA 
Daf. Bory Ann. Se. Phys. 
(1821) viii. p. 45; Ach. 
Lich. (1810) p. 571 (ut 
sectio  Cenomyces). — 
Thallus crustaceous at 
the base, persistent ; 
podetia papilleform, 
simple or branched, cor- 
ticate, glabrous. Apo- 
thecia small, terminal on 
the podetia ; spores 8nee, 
oblong, simple, colour- 
less; thece, especially 
the apices, bluish with 
iodine. Spermogones Fig. 34. 
normally terminal on the Pycnothelia papillaria Duf.—a. Sections of 
podetia, conical; sper- apothecia, X30. 5. A theca and paraphysis, 
matia cylindrical, and 350. ¢. Spores, x500. d. Section of a 
somewhat acute at either spermogone, x30. ¢. Sterigmata and sper- 
matia, x 500. 
apex, or slightly arcuate. 
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 0,009-0,014 mm. long, 0,0045 mm. thick.— 
Sm. Eng. Fl. v. p. 241; Gray, Nat. Arr. i. p. 424; Cromb. Lich. Brit. 
p. 18; Leight. Lich. Fl. p. 55, ed. 3, p. 52.—Cladonia papillaria 
Mudd, Man. p. 52; Brit. Clad. p. 34. Cenomyce papillarta 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, Madrepore instar 
nascens Dill. Muse. 107, t. 16. f. 28.—Brit. Ews.: Leight. n. 208 ; 
Mudd, n. 22, Clad. n. 80; Cromb. n. 121. 
The thallus in more barren habitats is somewhat determinate, and 
the podetia are often subverruceform, usually somewhat scattered, though 
