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 

 Snse, rarely 4nae or 2nae. 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 cyphellae. 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 (cfr. Flora, 1884, p. 219). 



Subtribe I. PELTIDEI Nyl. 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. The cephalodia are variable in their position, being either 

 epigenous or hypogenous or endogenous ; when rhizinae are present, they 

 are composed of fasciculate filamentosa 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 6 



erhizinose. Apothe- 

 cia adnate on the 

 marginal lobules of 

 the upper surface of 

 the thallus, ascending 

 or horizontal ; spores 

 3- or pluri-septate, 

 fusiform ; by menial 

 gelatine bluish with 

 iodine. Spermogones 

 unknown. 



A small genus dis- 

 tinguished from Pelti- 

 yera of the following 

 subtribe by the pre- 

 sence of cephalodia, pj g 43 



and by the nature of 



the gonidia. It con- Peltidea aphfkosa Ach. a. Section of (entire) thallus, 

 x200. b. Gonidimia, X 350. c. Them and para- 

 physis, x35U. d. Three spores, X500. 



tains only two species, 

 both of which occur in 



ir Islands 



