LECANORA] LECANORACE 267 
Apothecia reddish-brown. 
11. L. subfusca Ach. Lich. Univ. p. 393 (1810) pro parte (incl. 
var. argentata).—Thallus thinnish, opaque, developed beneath 
and above the bark, effuse or determinate, slightly wrinkled, 
unequal or occasionally granular, whitish or ash-grey 
(K + yellowish). Apothecia moderate in size, rarely up to 
2 mm. across, scattered or crowded, rather prominent and attached 
by a narrow base, rounded, the disc plane or generally convex, 
brownish-red, the thalline margin rather thin, not prominent, 
entire or sometimes slightly crenulate; paraphyses slender, 
subdiscrete, more or less distinctly septate, straight or flexuose, 
variously formed at the tips, sometimes slightly clavate or 
swollen, and tinged with a bright-brown ‘colour or embedded in 
a brown gelatinous epithecium ; spores oblong-ellipsoid, 11-16 
long, 7-9 » thick, but occasionally: larger ; hymenial gelatine 
blue, the asci dark tawny-coloured, with iodine.—Hook. FI. 
Scot. 11. p. 47 pro parte and in Sm. Engl. Fl. p. 189 pro parte ; 
Mudd Man. p. 146 pro parte; Cromb. Lich. Brit. p. 51 pro 
parte (incl. f. argentata) & Monogr. i. p. 409; fig. 65; Leight. 
Lich. Fl. p. 201; ed. 3, p. 185 (incl. f. argentata). Lichen 
subfuscus L. Sp. Pl. p. 1142 (1753) pro parte. 
Easicc. Johns. n. 110; Larb. Lich. Hb. n. 217. 
The species and varieties are distinguished by the thin thallus, 
best seen towards the margin, as in time it may become piled up and 
thickish towards the centre. The apothecia in the species have a 
prominent disc, the margin is thin and normally entire, but occasion- 
ally becomes crenulate. Spermogones in this and allied species are 
black at the opening, with mostly curved spermatia about 16-20 or 
~24 p long. 
There is a group of ‘“‘ forms,” ‘‘ varieties,” or ‘“‘ species ”’ intimately 
associated with Lecanora subfusca, and variously designated by 
different workers, probably all of them included under Lichen sub- 
fuscus L. A large series of these from different collections have been 
examined by Hue (Bull. Soc. Bot. Fr. 1. p. 22), and the results 
obtained by him have been verified on our British specimens. There 
are differences among them in the development of the thallus and of 
the apothecial margin, which are not sufticiently constant to be 
specific. The microscopic characters are also variable to some extent, 
but the differences there seem to be largely due to age. They include 
the form of the tips of the paraphyses which are slender and flexuose 
in all, and more or less conglutinate, but in some are slightly capitate 
or clavate, in others of equal width throughout. In the latter case 
they are colourless; the wider types are often brown, generally the 
epithecium is a brown gelatinous layer and granulose or non-granulose. 
Steiner (Verh. K.K. Zool.-Bot. Ges. lxi.) differentiated the typical 
species as having capitate paraphyses, but that character appears, 
though rarely, in several of the forms ; he also considered the inspersed 
granulose condition as specific, but that character also is untrust- 
worthy and seems to be a growth condition. The reaction with 
iodine, which Nylander relied on to determine species, is practically 
the same for them all: with a very dilute solution, the hymenium 
