OF FILAMENTOUS, FRUTICULOSE, AND FOLIACEOUS LICHENS. 265 
Species 4. P. alphoplacum, Wahl., 
Which occurs in North America, as well as in Europe. 
Specimen 1.—ScuARER exs. 330 (sub Parmelia radiosa 8. inflata); on granitic 
alpine rocks; with apothecia. The spermogones are marked by their small, 
brown ostioles, which crown the separate, sterile warts of the thallus. The sper- 
matia are short, rod-shaped, about sath to auth long, and s4nth broad. The 
sterigmata are apparently sub-simple, linear, branching below, measuring with 
the attached spermatia auth to'ith long. The existence of simple sterigmata 
in Placodium is quite exceptional,—arthrosterigmata almost universally occurring. 
SPecIES 5. P. teicholytum, DC. 
This is the type of a section of Placodiuwm characterised by the possession of a 
yellowish thallus (Syn. Parmelia erythrocarpia, Fr.; Lecidea, Scheer.; Blastenia 
erythrocarpia, Pers., Korb. 183; Lichen ceesio-rufus, Sin., E. B. 1040). This 
species, I think, should certainly be merged in Lecanora ferruginea, or, as I should 
arrange it, Lecidea ferruginea. The spermogones are scattered among the apo- 
thecia as blackish, punctiform, depressed bodies, sometimes slightly papilleeform. 
The form of the spermogonal cavity is oblong; it is narrow and simple. The 
spermogonal envelope is black, and this distinguishes the spermogone—on section— 
from the surrounding white medullary tissue. The spermatia are ellipsoid or 
ovoid, about sth long, on arthrosterigmata resembling those of P. murorwm. 
Species 6. P. fulgens, DC., 
A handsome species, which occurs both in Africa and Europe. The spermogones 
are large, distinct, orange-red tubercles, which are apt to be mistaken for, or con- 
founded with, the nascent apothecia. The internal tissue is whitish-yellow; the 
cavity is simple, but it is ultimately obliterated by convergent hypertrophied 
sterigmata. The sterigmata are ramose, and consist of small cubical cellules, 
which become almost solid from thickening deposits in their interior. The sper- 
matia are not above ~ath to qth long, and are in immense numbers. 
Specimen 1.—Hepp. exs. 194; on sandy ground, on the banks of the Rhine, in 
the neighbourhood of Tardisbriicke, near Chur. The spermogones are abundant 
as large, prominent, deep orange-red tubercles or cones, scattered towards the 
periphery of the thallus. They are most easily seen when moistened. The sper- 
matia are sub-ellipsoid, atomic in size, seated on the apices and sides of arthro- 
sterigmata which resemble those of Physcia parietina. 
Species 7. P. aureum, Scher., 
A beautiful native of the Alps and Pyrenees. 
Specimen 1.—Scu&RER exs. 165 (sub Lecidea) ; in the fissures of calcareous 
VOL. XXII. PART I. oY 
