DR. LINDSAY ON WEST-GREENLAND LICHENS. 349 
(lecideoid) apothecia there is the widest difference ; and it is perhaps not surprising that 
systematists should have variously referred the very numerous and puzzling forms of 
this most variable of all the Lecanore to the genera Lecanora, Urceolaria, and Aspicilia, 
and to a considerable number of supposed species of these genera ! 
In Kudlesæt specimens especially, crystals of hornblende, which protrude through the 
thallus, are apt to be mistaken for apothecia. When fresh these crystals are black and 
glistening, and under the lens their crystalline structure is at once apparent. When 
weathered they become brown and assume more of a biatorine aspect than the apothecia 
of cinerea usually present. In all cases their outline and surface are irregular and 
linear or angular, as contrasted with the smoothish surface and rounded outlines of the 
lichen-apothecia. The difference can therefore be easily detected on careful examination 
under the lens. In all the Greenland forms of cinerea the asci and hymenial gelatine 
assume a very deep blue under iodine. The paraphyses are generally indistinct; in all 
cases short, and compactly arranged. The sporidia vary considerably in size, form, and 
structure. Their length varies from :00015” to 00020" in mierosporous, and to :0006” in 
macrosporous conditions; while their breadth in the former states is 00009" to *00015", 
in the latter 0003" to -00045". Their shape varies from ellipsoid, through oval, to sub- 
spherical. They are always simple and colourless, sometimes possessing double contour, 
occasionally finely granular or muco-granular; or they exhibit one or more (generally 
central) largish, prominent nuclei. 
What was given to me while in Norway in 1857 by the late Professor Blytt as L. 
Myreni is apparently only one of the many forms of cinerea*. Here the apothecia are 
sometimes lecanorine, resembling those of atra, having a prominent raised thalline 
margin. But in other parts of the same thallus they are lecideine and immarginate, sub- 
convex sometimes, even substipitate, or at least prominently seated on thalline eleva- 
tions. In the latter case the thallus is generally old, having become subgranular and 
thin, worn away by weathering—a circumstance that is further shown by the relatively 
greater size and prominence of the protruding hornblende crystals. The old apothecia 
are sometimes deformed—a condition that is common to those of all Lecanore and Lecidea 
in arctic and alpine countries. 
L. cinerea is one of the many crustaceous lichens (abundant in most parts of the 
world) the forms of which exhibit a diversity as great as is the variety of conditions 
regulating growth. ‘Few of these forms or conditions deserve separate rank or nomen- 
clature, by reason of the inconstancy of their characters. Yet systematists manufacture 
out of them both genera and species, and are constantly altering the names and rank of 
these subdivisions—e. g., “ species” being reduced to the position of “ varieties," while 
the latter are elevated to the rank of species +. 
l4. L. calcarea, Ach.—Jakobshavn and Kudleset, on the same trap rocks as Z. 
cinerea, to which, indeed, I refer it as a mere form. Thallus frequently very white or 
cream-coloured, and farinose, or irregular and tartareous, giving at once with potash a 
» * The assignation of L. Myreni in my ‘ Northern Lichen-flora (p. 385) to Lecidea amylacea, Ach. and Whlnb,, is 
therefore an error. 
+ Vide my ‘Northern Lichen-Flora,’ p. 382. 
