•J 



rKLTlGKllF.I. 



277 



marginal and adnate eif.her to the upper or the lower surface, or 

 innate and scattered on the ujjper surface of the thallus ; spores 

 8nffi, rarely 4naj or 2n8e, colourless, se])tate and fusiform in the 

 marginul ai)othecia, brown, ellipsoid and bilocular in the scattered 

 apothecia ; paraphyses discrete, articulate, usually thickish. Sper- 

 roogoncs (in so far as known) innnerscd in the tliallus, with jointed 

 sterigmata. 



Nylander points out the analogies of this tribe in various respects to 

 Stictei (I'yr. Or. p. •'<! note): but being less developed, it occupies an 

 inferior place. The tliallus for the most part is without a cortical layer 

 on the lower surface, where also it is destitute of cyphellfc. 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 arrangeuient 

 it is divided into the two following subtribes, distinguished from esich 

 other by anatomical characters (cfr. Flora, 1884, p. 219j. 



Subtribe I. PELTIDEl Xyl. Flora, 1882, p. 457, 1884, p. 21iJ. 



Thallus bearing cephalodia ; gonidial layer composed of gouidimia. 

 Apothecia and spores variable as in the tribe. 



Well characterized by the thallus being cephalodiiferous and gonidi- 

 miose. Of the three genera, Xephroma, Feltidea, and tSolorina, the tirst 

 does not occur in (ireat 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, beuig either 

 epigenous or hypog-'nous or endogenous ; when rhizinae are present, they 

 are composed of fasciculate hlamentose elements. 



49. PELTIDEA Ach. :Meth. (1803) p. 282 pro parte ; Xyl. Flora, 

 186G, p. lltj. — Thallus fragile, the coitical layer not continuous on 

 the under surface, 



b 



which is nerved ntjd 

 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 I'clti- 

 (jvra of the ibllowiug 

 subtribe by the pre- 

 sence of cephalodia, 

 and by the nature of 

 the gonidia. It con- 

 tains only two species, 

 both of which occur in 

 our Islands. 



Fig. 48. 



Pelt idea aphfhosa Ach. — a. Section of (entire) thallus, 

 x2(M). b. Gonidiinia. x350. c. Thec.a and para- 

 pliysis, X 350. d. TJiree spores, X oOO. 



