334 DR. LINDSAY ON WEST-GREENLAND LICHENS. 
few of the so-called “ species ” are to be regarded as mere conditions, e. g. erosa, cylindrica, 
and proboscidea. 
4. U. vellea, L.—Egedesminde, sterile. The natural grey of the thallus is changed into 
deep olive-green by potash,—a reaction which, however, is equally produced by bleaching- 
solution and by water—one which is common in the foliaceous lichen-thallus, and one 
that has no significance or value. Various forms of Parmelia sawatilis and Physcia stel- 
laris grow on its old thallus, sometimes on its upper grey cracked surface, sometimes on 
the lower, copiously fibrillose, black or brown one. In the Kew Herbarium, apothecia 
are rare in this so-called * species," while Greenland specimens are sterile. 
My herbarium contains two specimens apparently of vellea, collected by the late Henry 
Paul, of Edinburgh, in or before 1851, the one labelled * Norway," the other “ Dunoon ” 
(Argyleshire). I examined both in 1852, and found them to possess 2-locular sporidia, a 
condition apparently not previously observed, or recorded as occurring, in the genus Umbi- 
licaria, none of the British species, as then described, having sporidia of other character 
than simple. I found, however, that in several European species of Umbilicaria there is 
a tendeney, not only to bilocularity of the sporidia, but to muriform division, as well as 
to the acquisition of colour (e. g. spodochroa). These conditions of the sporidia have been, 
long subsequent to my observations, found by other authors in various foreign Umbili- 
carie (e.g. flavovirescens and haplocarpa). In the Dunoon vellea the sporidia are large 
and distinct, generally 2-locular, sometimes simple; loculi pale yellow or colourless, gra- 
nular or not, according to age; generally broadly oval, frequently pyriform, variable in 
size and form, having sometimes a projection at one end, indicating the commencement of 
germination. Asci sometimes 1-spored ; that is (as is common in the genus), only one 
sporidium reaches maturity. In other cases there are 4 to 8 sporidia in each ascus. 
Possibly there may have been some transposition of the labels in Paul's *Dunoon' 
plant, both suites of his specimens being really Norwegian. But not necessarily; for 
Mudd (Brit. Lichens, p. 120) gives vellea as a British species, he having seen specimens 
from Lancashire. My own Dovrefjeldt specimens, collected in 1857, are sterile. 
U. flavo-virescens, Leight. (Journal of Linn. Soc. vol. x. Botany, p. 33), a South-African 
species (if it is an Umbilicaria at all), has 2-locular, brown sporidia, as has also U. haplo- 
carpa, Nyl., a Peruvian species, in which there are 6 sporidia in each ascus. Such irre: 
gularities in the number of sporidia in each ascus would now appear to be common. The 
spermatia and sterigmata of U. flavo-virescens, as figured by Leighton (Pl. iv.), are not those 
usual in Umbilicaria, while the — are flat, simple and lecidine, a condition, how- 
ever, less unusual. 
Paul's Norwegian specimens bear a white parasite— possibly a neun 
grows on and about the apothecia. It possesses, however, the structure of the 
apothecia already deseribed in the Dunoon plant; and though Mr. Leighton, who 
kindly examined the specimens, refers the 2-locular sporidia “indubitably ” to the said 
fangus, 1 believe they really belong to the normal apothecia of the Umbilicaria. The 
asci give a pale blue with iodine, a circumstance which is at least suspicious in any 
reference of them to a parasitic fungus. The paraphyses cohere at the apices, which are 
brown; their filaments are very delicate. The asci are large, 8-spored; one or more 
