330 DR. LINDSAY ON WEST-GREENLAND LICHENS. 
dothideoid mottling was sometimes so copious as to give the appearance of panniformis 
or vittata. This mottling is probably attributable to Dothidea homostegia, Nyl., which 
generally occurs in a sterile, abortive, or degenerate condition, as is too frequently the 
case with lichenieolous Micro-fungi in general*. In this sterile condition, I have very 
often met with this fungus on P. saxatilis, affecting generally the peripheral, and smooth 
or normal, laciniæ. In its fertile state I have found it only in one or two instances, e. g. 
on P. saxatilis from Barmouth, North Wales, collected by Mr. Leighton in June 1856. 
The parasite here occurs on the microphylline thallus, as black, sublecideoid glomeruli, 
surrounded by a black discoloration or shading of the thallus of the Parmelia. This 
shading often connects two or more groups of glomeruli, forming large, black, irregular 
mottlings of the thallus. The individual fruit-elusters or perithecia vary in size accord- 
ingly as they are young and comparatively simple, or old and compound or confluent; in 
the former case being verrucarioid papille, in the latter, convex, apothecioid, superficial 
bodies, like the apothecia of a Lecidea (e. g. parasema). 
Regarding this parasite, my friend M. C. Cooke wrote me in 1866 as follows :—** On 
it” (the Parmelia saxatilis) “are two or three clumps of Spheria, in fruit, almost the only 
truly mature one which I have found amongst your Spherie on Lichens. This is cer- 
tainly a Dothidea, with 3-septate spores, and agrees with specimens sent me from Ger- 
many, under the name of Spheria homostegia, Nyl. (Prodr. p. 56). I call it therefore 
Dothidea homostegia, and hope you will find it again, as it is a good Dothidea.” 
On some degenerate conditions of the thallus of P. saxatilis, what appears to be a 
Torula studs the surface, as numerous, minute, irregular, black papille. This structure, 
however, is indistinct; and the parasite may therefore really be some of the other licheni- 
colous Micro-fungi, which infest the thallus of many of the Umbilicarie, Cladome, 
Lecanore, and other genera. 
But the most important parasite on Greenland forms of P. saxatilis is what I propose 
to distinguish by the name of the pioneer of Greenland colonization (Hans Egede) as 
Lecidea Egedeana. 
It occurs plentifully on some forms, on the central portions of the thallus, on old 
cracked laciniæ. The apothecia have the colour and appearance of those of L. cornea, 
Sm., than which they are smaller; they are flat, margined, crowded, with difficulty seen 
even under the lens. Fertile asei are very delicate; 8-spored. Hymenial gelatine very 
faint lilac or blue with iodine. Paraphyses with pale brown, agglutinated tips. Sporidia 
brown, 2-locular, broadly ellipsoid ; :0006” to :0009” long, and :0003” to :00045” broad. 
Their general appearance is that of the sporidia of Physcia stellaris and its allies, rather 
than those of Lecanora sophodes or Lecidea disciformis. As is frequently the case in 
alpine, arctic, and even old, specimens or species of lichens, degenerate asci are common, 
having the aspect of brown, ribbon-like masses. i 
. Some of the Greenland forms of P. saxatilis examined by me occupied unusual posi- 
tions: thus, I met with it on some large scyphi of Cladonia pyxidata, and on the lower 
surface of the old thallus of Umbilicaria vellea, just as I have found Physcia pulverulenta 
* What is probably this parasite is figured in my ‘Mem. Spermog. pl. xii. fig. 2, on P. physodes. It also occurs 
on the thallus of saxicolous forms of P. Borreri, Ach., in Bolivia (Nyl. Lich. Exot. p. 215). 
