48 THELOSCHISTES. 



8. euploca (T.uckerm.) Trev. ; thallus smooth but dull, fus- 

 cescent, or now whitening above ; beneath white; the regularly 

 very much divided, filiform branches scarcely a little compressed, 

 intricately interlacing; apothecia small, scattered, sessile ; the 

 flat, rufous-fuscous disk finally convex, and excluding the mostly 



entire margin. Spores, -jj^ mic. Physcia, Tucker m. Suppl. 1, 



I c.p. 424. Obs. Lich. I. c. 4, p. 388. Nyl. Syn. 1, p. 413. 



Shaded rocks on the banks of streams, in Western Texas 

 (Wright] Tuckerman I. c. 1858. On calcareous rocks in Kansas, 



Hall. More appressed, and much more regularly limited than 



Parmelia lanata (L.) Wallr. ; and it is perhaps easier, on most 

 accounts, to refer the Texan plant to Physcia, than the other to 

 Parmelia. But we cannot overlook the fact that the spores of 

 our Texan lichen are irreconcilable with those of Physcia; as 

 the whole plant is with Theloschistes. 



IX. THELOSCHISTES, Norm., Emend. 



Apothecia scutellseform, the disk yellow. Spores ellip- 

 soid, polar-bilocular (the spore-cells occupying the tips of 

 the spore and conjoined more or less by a tube) or (n. 3) 

 simply bilocular; or simple; colourless. Spermatia ellipsoid, 

 and oblong; on multi-articulate sterigmas. Thallus folia- 

 ceous j or now reduced and squarnulose ; appressed ; or now 

 ascendant and EverniaBform; cartilagineous-membrauaeeous, 

 mostly yellowish. A well-defined group, offering diffi- 

 culties only in its relation to Placodium in Lecanorei ; from 

 which it is yet distinguished exactly as Lecanora from Par- 

 melia. The anatomy of the thallus is explained in Schwend. 

 Untersuch. I. c. 2, p. 157, 161, t. 4,/. 16-17; 3, p. 154, 160, 

 t. 8, /. 10-12. It is observable that the considerable ana- 

 tomical differences between the Everniaiform and the folia- 

 ceous types of Theloschistes (differences soon to recur again 

 in Physcia) are insufficient to obscure the naturalness of 

 their association as members of the same genus. 



* Thallus ascendant; the cortical layer not parenchymatous ; 

 the medullary in part now coalescing into solid cords. 



1. T. chrysophthalmus (L.) Norm.; thallus tufted, erectish 

 or spreading, or at length pendulous, sub-cartilagineous, more or 



