
OF FILAMENTOUS, FRUTICULOSE, AND FOLIACEOUS LICHENS. 231 
its whole surface more or less mealy. The spermogones are scattered chiefly peri- 
pherally ; in some the ostiole is depressed, in others it is girt by a slight ring of 
the thallus, giving it a pseudo-papillate aspect. 
Specimen 2.—On the bark of trees, Riverstown, Cork; coll. Carrotu. On one 
specimen there are a few old spermogones, dotted about the margin of the lobes 
of the thallus; some of them appear seated on a flattened thalline papilla, others 
are girt by a thalline ring, as in No. 1. 
Specimen 3.—LEIGHTON exs. 231 (Eng. Bot. t. 1780); Twycross, Leicester- 
shire; no apothecia. The thallus is abundantly sorediiferous. The spermogones 
are peripheral in regard to distribution; the spermatia are short and acicular, on 
articulated, ramose, delicate sterigmata, as in P. tiliacea. 
Specimen 4.—ScH#RER exs. 361 (sub Parmelia dubia); on trunks of trees and 
palings, Switzerland. A few spermogones are dotted over the margins of the lobes, 
but they are old, and contain no free spermatia. 
Specizes 18. P. conspersa, Ach. 
A cosmopolite. There are two chief forms of the plant: one with narrow, linear 
convex lacinize, the var. stenophylla, or minor, of some authors; and the other, 
with broad, round lobes, flattened, and resembling occasionally P. caperata, usually 
described as var. major. Ina very large suite of specimens I have examined, from 
every part of the world, in the Hookerian Herbarium, Kew, I have rarely found 
spermogones absent. Moreover, they generally occur in great plenty scattered 
over the whole surface of the lacinize, or thallus. So much so is this the case, 
that the name of the plant may be supposed to have been bestowed in allusion to 
the great profusion of the spermogones. They are usually minute, black, puncti- 
form, immersed bodies, with an imperceptible ostiole. But, with age, the latter 
expands and becomes patent, having either a round, triangular, or stellate-fissured 
shape, as is the case in P. sawatilis and P. physodes. Hence, the plant is frequently 
studded over with a profusion of black, lacerate perforations, which are the ostioles 
of old spermogones. It frequently happens that the apothecia of this species are 
degenerate or abortive; the disk falls out, and a cup-shaped cavity remains, of the 
same colour as the exciple and the thallus. The exciple, at the same time, gene- 
rally becomes corrugated, and the whole organ assumes a coarse, warted appear- 
ance. On these apothecia, disk and exciple alike, the spermogones are frequently 
studded as plentifully as on the thallus, giving them a peculiar black-punctate 
character. KorsbeEr apparently implies that the apothecium becomes barren and 
degenerate as a consequence of the spermogones taking possession of it as a site. 
But I see no evidence for regarding the phenomenon either as a propter hoc, or a 
post hoc. It rather appears to me that, the apothecia being degenerate from other 
causes, the spermogones are developed upon them. Were we theorizing, on physio- 
’ logical and analogical grounds we might suppose that the spermogones should be 
