344 DR. LINDSAY ON WEST-GREENLAND LICHENS. 
in Spitzbergen, and generally throughout the arctic lands and islands. The asci and 
.sporidia are those of a Pertusaria, or Pertusarioid Lecanora, such as L. bryontha. The 
hymenium gives a blue reaction with iodine. The thallus, especially when young, gives 
a lemon-yellow with potash. No reaction occurs with bleaching-solution. Water has 
the same effect as potash, in a minor degree—a circumstance that renders this greenish- 
yellow coloration under potash.of little or no significance in the lichens in which it 
occurs. 
I met with two or three different Parasites on Greenland forms of L. oculata. Of these 
the following is of an unusual character. It occupies small wartlets of the horizontal 
thallus of the Lecanora, clustered at the base of the columns. These wartlets are crowned 
with an irregular, stellate-fissured, ostiolar disk of the same obscure brownish-green colour 
as the apothecia of the Lecanora. The disk expands under moisture. The wartlets in 
question might be supposed at first sight to be the spermogonia of the Lecanora. But 
they contain hymenial tissue and sporidia, not sterigmata and spermatia. The hymenium . 
gives a yellow (no trace of a blue) colour with iodine. The asci are 8-spored, sublinear, 
:0012" to 0015” long, and :00022” broad. The young protoplasm is, as usual, granular. 
Neither the paraphyses, which are very delicate and indistinct, as in Verrucaria, nor the 
hypothecial tissue is coloured as is usual in the higher lichens. The sporidia are 
arranged in a single series in each ascus, about :00015” to :00020” in diameter, being 
spherical, like those of Lecidea lugubris*, than which they are smaller. This parasite 
has the external aspect of a verrucæform or papillar Pertusaria, and I therefore assign to 
it the name 
Pertusaria paradoxat. 
Its sporidia are very different from those of Pertusaria ; but I know of no better pro- 
visional position than in that somewhat heterogeneous genus. The colour of the disk 
and hymenium, and their occupation of the ordinary wartlets of the thallus of the host, 
are also striking peculiarities. 
While examining the lichens of the Kew Herbarium in 1858, I met with a plant 
having very similar characters to Pertusaria paradoxa. The specimen was labelled by 
Borrer, 1805, was apparently referred to Lecidea luteola, Ach., and was no doubt 
English, though no locality was given. The apothecia or perithecia were precisely of 
the character of those of P. paradoxa, being subconical warts, with a radiate disk having 
a very torn, irregular margin. The sporidia were simple, colourless, oval, resembling 
those of Lecanora subfusca, but much smaller. Both this lichen and Pertusaria paradoxa 
are apparently closely allied to Lecanora protuberans, Sinrf. (Th. Fries, L. Arct. p. 102). 
* Vide author's paper on L. lugubris, Quart. Journal of Microscop. Science, vol. v. 1857, pl. xi. The sporidia of the 
Lecidea are more regularly spherical, and usually exhibit a distinct double contour. Somewhat similar; also, are the | 
sporidia of Lecidea fuscescens, Smrf., in Nylander's Exs. No. 135, which I found spherical, not ellipsoid, as described 
by Th. Fries (L. Arct, p. 197). | 
T A somewhat similar lichen Th. Fries has apparently described as var. pertusarioides of L. tartarea (L. Arct. 
p.100) But, unless we admit L. oculata to have two forms of apothecia on the same thallus, the pertusarioid 
‘apothecia in >ır Greenland plant must be considered pee 
