78 



glaucescent becoming cinerascent and brown ; pale and scarcely 

 fibrillose beneath ; the very thin, flat lobes compaginate, disap- 

 pearing for the most part at the centre in a granulose crust ; 

 apothecia small, and very small ; disk blackish-brown ; margin 

 entire, scarcely ciliate. Spores ^ mic. Spermatia elon- 

 gated, acicular. Nyl. Syn. 1, p. 428 ; Flora, 1862, p. 355. 



Parmelia obscura, v. adglutinata, ScJicer. Spicil p. 444. Physcia, 

 Tuckerman 1. c. p. 399. 



* pyrithrocardia, Miill. j thallus more or less saffron- coloured 

 within. Flora, 1880, p. 278. 



Upon trees and shrubs. New England, Tuckerman I. c. 1860; 

 westward to Illinois, Hall, and Wisconsin, E. L. Greene ; south- 

 ward to South Carolina, Eavenel ; Florida, Beaumont ; Alabama, 

 Peters-, Louisiana, Hale; and Texas, Wright. * Massachu- 

 setts, Willey. Eemarkably characterized by the spermatia. 



The lichen is better exhibited here than in Europe, and appears 

 at length, as Nylander has said, to pass into P. obscura. From 

 that species the present differs very considerably in the impor- 

 tant respect of the fibrils, or want of them ; but agrees with it 

 in the abnormal variation of the colour of the medullary layer. 



XII. PYXINE, Fr., Tuckerm. 



Apothecia sub-scutellseforrn. Hypotheciurn black ; and, 

 in the second section, the whole exciple blackening and 

 Lecideoid. Spores oblong-ellipsoid, bilocular (rarely, in 

 tropical regions, 4-locular) brown. Spermatia oblong, on 

 pauci-articulate sterigmas. Thallus now aduateand aggluti- 

 nate (semi-crustaceous) and now rising into foliaceous and 

 cartilagineous expressions ; the under side more or less fib- 

 rillose. In the parenchymatous cortical layer of the upper 



side of the thallus, as in some other respects of thalline 

 structure, this genus resembles Physcia ; and its very incon- 

 gruous apothecia are found yet, in the first section always, 

 and to some extent in the second, to offer no external dif- 

 ferences from those of the other ; with which it also agrees 

 in its spore-history. 



*Dirinaria. Apothecia scutellceform. Thallus normally 

 white within. 



