342 DR. LINDSAY ON WEST-GREENLAND LICHENS. 
In corticolous forms, occurring on Betula- and willow-stems, the asci are 8-spored, the 
. sporidia oval, colourless, simple, granular; sometimes, in the young state, :0009" to 
0012" long, and :0006" broad. 
On various forms of tartarea, 1 met with a black verrucarioid parasite, possessing both 
sporidiiferous perithecia and spermogonia. It occurred (e. y.) on the verrucæform thallus 
of the Lecanora, about Godhavn, seated, like 4brothallus, apparently on special growths 
of, or from, the said thallus. The parasite is punctiform or papillzform, the perithecia 
being seated on the irregularities of the thalline warts. When occurring as large papillæ, 
these perithecia resemble in external character the smaller apothecia of Adrothallus 
Smithü. The asci are 1- to 4-, never 8-spored, their size about :0024” long, and :0004" 
broad. 'The sporidia vary considerably, equally in length and breadth; their length 
ranges from :0006" to ‘0009" ; their breadth from :00015" to *00030". In form they are 
oval, sometimes fusiform, generally straight, sometimes slightly curved. In maturity 
they ane 3- to 8-locular, the number of septa varying considerably, 2 or 3 being com- 
mon, while there are sometimes 4 or upwards. "The epispore frequently bulges in matu- 
rity opposite the loculi of the endospore. In the young state, within the asci, the 
sporidia are sometimes simple and very granular, or they exhibit only rudimentary 
divisions into loculi. Their colour, according to age, varies from hyaline or pale olive 
(within the asci) to deep or blackish brown. The sporidia are frequently abortive or 
degenerate, and are then of a deep brown colour. Even in this condition they are 
also sometimes simple, or show only traces of division, Sometimes only one sporidium 
is developed in an aseus, acquiring in that position a brown colour, though the remain- 
ing protoplasm of the ascus is hyaline. Occasionally chains of 4 sporidia occur, the 
wall of the ascus having disappeared; or 2 sporidia adhere, and carry as a sort of caudal 
appendage the degenerate protoplasm, or the pedicle of the ascus. In young asci, the 
protoplasm (as it generally is in lichen-asci) is granular, usually colourless, sometimes 
becoming pale olive. | 
This parasite has not, so far as I can discover, been previously detected or described. 
As an apparently new form, therefore, I give it the appropriate name VERRUCARIA 
TARTARICOLA. 
What appear to be its spermogonia occur on similar, but separate, thalline warts, 
studding more copiously their verrucosities, much more numerous, minute, and crowded 
than the sporidiiferous perithecia. | 
Parasitic perithecia, externally resembling those of Verrucaria tartaricola, occur 
on the thallus of var. gonatodes, which, about the Illartlek glacier, coats grass, 
leaves, stems, twigs, and mosses. Here the black parasite is very conspicuous on the 
beautiful white, thin, papery thallus, being dotted copiously over its periphery. But 
the internal structure differs from that of Y. tartaricola in the asci being always 
8-spored, and the sporidia colourless. The paraphyses are filiform and very delicate, 
hyaline throughout, flexuous and interwoven, sometimes indistinct. The asci are sub- 
saccate and subarthonioid, with a very short, inconspicuous pedicle. They occur in tufts 
amidst the web of the paraphyses. They exhibit a brownish-red reaction under iodine, 
