DR. LINDSAY ON WEST-GREENLAND LICHENS. 339 
Gen. 15. UMBILICARIA. 
1. U. cylindrica, L.—Jakobshavn, fruit abundant; Egedesminde, on granite and 
gneiss, without apothecia, but spermogoniferous. "Thallus sometimes very thick and 
coriaceous, dwarf and complicate; colour of upper surface sometimes ashy grey, be- 
coming olive-green on moisture, sometimes very white, these white or grey conditions 
apparently being accompaniments of age. "The white forms are sometimes also sparingly 
white-pruinose. Under surface sometimes beautifully peach, pink or buff-coloured. 
The cortical or medullary tissues give no reaction either with bleaching-solution or 
potash. Marginal fibrille of thallus seldom very prominent or long. Sometimes, 
however, they are long, tufted, and as pale as the under surface of the thallus. 
This under surface is sometimes very fibrillose or densely rhizinose, at other times 
almost nude. Apothecia frequently deformed or degenerate, most irregular or angu- 
lose; sometimes in forni resembling those of anthracina, save as to gyri; compound 
from the opening up of these gyri; sometimes, when degenerate, white in all their 
parts, like the thallus; frequently stipitate (in age) to various degrees.  Sporidia 
of same size and form as in arctica. Spermogonia frequently, or generally, only peri- 
pheral; sometimes large and verrucarioid, conspicuous on the ash-grey thallus; more 
generally punctiform, frequently immersed and inconspicuous compared with those of 
arctica; become more prominent and brown under moisture; vary in size; frequently 
clustered. Spermatia in myriads; oblong corpuscles, atomic in size, shorter and broader 
than those of arctica. 
2. U. arctica, Ach.—Jakobshavn, on granitie stones; fruit abundant, with characters 
of the Scotch plant. Passes into proboscidea on the one hand, and hyperborea on the other, 
if the latter is not to be associated with arctica under a single type. The thallus gives 
no reaction either with bleaching-solution or potash. In Greenland specimens in the Kew 
Herbarium, the thallus is sometimes complieate; and these forms are generally the most 
plentifully spermogoniferous. Spermogonia occur as conspicuous, minute, black papillæ, 
perched on the rugosities of the thallus, chiefly about the periphery, semiimmersed. 
Spermatia rod-shaped, in myriads. Sporidia simple, oval, colourless ; 00040" long, and 
00022" broad. Some specimens of arctica are copiously studded over with a minute, 
- black, papillæform parasite, which may be confounded externally with the spermogonia. 
Unfortunately it exhibits no structure, so that it is impossible to refer it to Dothidea 
lichenum, Smrf. (Th. Fries, L. Arct. p. 165), or Tichothecium grossum, Körb. (Parerga, 
pp. 40 & 469), which have been described as parasites on arctica, the one as a fungus, the 
otlier as a lichen. 
3. U. hyperborea, Ach.—Jakobshavn, in fruit; Illartlek Glacier, about its base, also 
in fruit; Egedesminde, a few sterile fragments. Thallus only once gave a faint red colour 
with bleaching-solution. In the British-Museum ‘Herbarium I found a large patch 
of hyperborea from Greenland. In that of Kew, in a specimen of the same species, 
from Walden Island, the sporidia are simple, oval-oblong, and :00050” long by :00020” 
broad. It seems to me to be a very arbitrary and unphilosophical classification which 
separates hyperborea and arctica. In truth, among the European Umbilicarie there are 
very few types that stand clearly forth by easily distinguishable characters, while not a 
