PELTIDEA. ] PELTIGEREI. 277 
marginal and adnate either to the upper or the lower surface, or 
innate and scattered on the upper surface of the thallus: spores 
8nx, rarely 4nez or 2ne, colourless, septate and fusiform in the 
marginal apothecia, brown, ellipsoid and bilocular in the scattered 
apothecia; paraphyses discrete, articulate, usually thickish. Sper- 
mogones (in so far as known) immersed in the thallus, with jointed 
sterigmata. 
Nylander points out the analogies of this tribe in various respects to 
Stictei (Pyr. Or. p. 31 note); but being less developed, it occupies an 
inferior place. The thallus for the most part is without a cortical layer 
on the lower surface, where also it is destitute of cyphelle. It is a small 
tribe, though most of the species are widely distributed in the colder and 
more temperate regions of the globe. In Nylander’s recent arrangement 
it is divided into the two following subtribes, distinguished from each 
other by anatomical characters (¢fr. Flora, 1884, p. 219). 
Subtribe I, PELTIDEI Ny). Flora, 1882, p. 457, 1884, p. 219. 
Thallus bearing cephalodia ; gonidial layer composed of gonidimia. 
Apothecia and spores variable as in the tribe. 
Well characterized by the thallus being cephalodiiferous and gonidi- 
miose. Of the three genera, Nephroma, Peltidea, and Solorina, the first 
does not occur in Great Britain. It is distinguished from the others by 
the thallus being continuous beneath, with the apothecia adnate on its 
lower surface. ‘I'he cephalodia are variable in their position, being either 
epigenous or hypogenous or endogenous; when rhizine are present, they 
are composed of fasciculate filamentose elements. 
49, PELTIDEA Ach. Meth. (1803) p. 282 pro parte; Nyl. Flora, 
1866, p. 116.—Thallus fragile, the cortical layer not continuous on 
the under surface, : 
which is nerved and 
erhizinose. Apothe- ®@ 
cia adnate on the 
marginal lobules of 
the upper surface of 
the thallus, ascending 
or horizontal ; spores 
3- or pluri-septate, - 
fusiform ; hymenial 
gelatine bluish with 
iodine. Spermogones 
unknown. d 
A small genus dis- 
tinguished from Pelt?- 
gera of the following z a 
subtribe by the pre- 
sence of cephalodia, Fig. 48. 
and by the nature of 
the gonidia. Itcon- Pyitidea aphthosa Ach.—a. Section of (entire) thallus, 
tains only two species, x 200. 6. Gonidimia, x 350. cv. Theea and para- 
both of which occur in physis, * 350. d. Three spores, x 500. 
our Islands. 
