DR. LINDSAY ON WEST-GREENLAND LICHENS. 345 
Both the columns, and horizontal, verrucose thallus of the Greenland L. oculata are 
studded over with a very minute, black, punctiform parasite, which is partly of the 
nature of pycnidia, containing myriads of stylospores, resembling those of similar 
pycnidia in Cladonia fimbriata; brown or olive, spherical to pyriform; when spherical, 
about *00015" in diameter; sometimes oblong and cohering in chains, like the spores of 
Torula; then deep brown, :0003" long and :00022" broad. The envelope is deep brown 
and cellular. The constituent tissues give no reaction with iodine. It is extremely 
unlikely that these pycnidia are referable, as a secondary form of fructification, either to 
the Lecanora or Pertusaria. It is possible, however, that the perithecia, which contain 
the deep-brown, concatenate, oblong spores are referable to a different parasite from that, 
which contains the much smaller, more delicate, isolated or free stylospores. In this 
case, the first-mentioned group of perithecia may belong to Torula lichenicola*: 
On a specimen of L. oculata (sub nom. Lichen dactyliferus, Whlnb.) in the Kew Herb., 
I find a parasite of a very different kind from any of those which occur on the Greenland 
plant. Seated on and partially immersed in some of the thalline warts are apothecia, 
black, flat, rough on the surface, slightly urceolate sometimes, which appear to be deve- 
loped in, and ultimately to burst through, though they do not project above, the thalline 
warts. The asci and sporidia resemble those of certain Calicia, the sporidia being 
brown, 2-locular, oval, or figure-8-shaped (having a constriction at, or opposite to, the 
central septum), :00050" to :00066" long and :00025" broad. 
4. L. bryontha, Ach.—Mlartlek. A most interesting lichen, having certain characters 
both of Lecanora and Pertusaria, and forming a connecting link between these genera. 
The apothecia are those of Lecanora. There is an open, convex disk, concealing the 
thalline exciple. The sporidia and asci are those of Pertusaria. The sporidia are very 
large, 0060" long and :0024" broad, simple, oblong-oval; double contour distinct; pro- 
toplasmic contents finely granular or muco-granular, intermixed with much oil-globules, 
‘as is common in Pertusaria. The asci are also very large, :0075” long and -0024” broad, 
l-spored, blue with iodine; none of them seen in their entire length on the field of the 
microscope. Both asci and sporidia resemble those of Pertusaria communis. 
The Greenland plant is quite the Pertusaria macrospora, Næg., of Hepp's Exs. No. 
424, and of Mudd's * Brit. Lichens,’ p. 277, with certain trivial modifications. The disk 
has the same dull greenish-brown colour as in Hepp's Swiss specimens; but the apothe- 
cial verrucæ in the Greenland plant are more elongated, more like the columns of Z. 
oculata, more isidioid or stipitate ; while the disk is so convex and tumid as to conceal the 
usual thalline margin. 
It would be equally proper to class this lichen as a Zecanora or a Pertusaria. Inasmuch 
as the external (morphological) characters should always, if possible, take precedence of 
internal (structural) ones, I prefer arranging it, on account of its apothecia, as a Leca- 
nora, beside L. oculata. Th. Fries (L. Arct. p. 117) gets over the difficulty of the Pertu- 
sarioid sporidia by creating specially for this single lichen a separate (sub-)genus, 
Pionospora, characterized by large single sporidia, and which he conveniently considers 
* A new species described in * Observations on new Lichenicolous Miero-Fungi," Trans. Royal Society of Edin- 
burgh, vol. xxv. pp. 515 & 530; and Proceedings, vol. vi. p. 534. 
VOL. XXVII. 
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