348 DR. LINDSAY ON WEST-GREENLAND LICHENS. 
olarioid or sorediiferous) states of L. tartarea. They also grow occasionally on old Umbi- 
licarie, or the rudimentary horizontal squamules of Cladonia. The apothecia are some, 
times very large, at other times very small; their disk very black, or as brown as in sub- 
fusca, convex or flat. The larger apothecia have sometimes a squamulose or crenulate, 
or irregularly wavy, exciple, like that of Pannaria brunnea. The exciple is sometimes 
very white, and then conspicuous, or very dark, and then apt to be confounded with the 
disk. The whole apothecium, especially when small, may then be mistaken for that of a 
Lecidea—the more so that the Lecanora is frequently associated with various forms of 
Lecidea parasema. The examination of the sporidia, however, at once distinguishes the. 
two very different plants. In the Lecanora they are normally deep brown and 2-locular, 
ellipsoid or oval, with or without a central constriction opposite the septum (becoming in 
the former case figure-8-shaped), varying considerably in size, from :0006” to 0009" long 
and 00030" to 00045" broad. In the young state they are sometimes simple and olive; 
or the contents show a tendency to, or distinct, bilocularity, the loculi having bold out- 
lines, surrounded by a broad hyaline envelope so delicate as to resemble mucus. Occa- 
sionally the young sporidia are slightly curved as in Physcia and Ramalina. There is con- 
siderable variety in structure, resembling, in this respect also, some of the Physcie (e. g. 
stellaris or pulverulenta). Sometimes there are three large prominent nuclei. Occasion- 
ally there is a protrusion of the epispore at each end—apparently the first effort at ger- 
mination. Sometimes the loculi assume a bipolar character—isolated, or connected, as 
in certain Physcie, both of the stellaris and parietina groups. In the young state, the - 
sporidia are more frequently pale-olive than colourless. Sometimes the loculi are granular, 
or exhibit both nuclei and granules as in Abrothallus Smithii and many other lichens, 
which have brown 2-locular sporidia. The hymenial gelatine assumes a beautiful blue 
colour with iodine, as do also the asci; and the latter when full of young sporidia, whose 
loculi are nuclear and 2-polar, pale olive, prominent, button-like bodies, are fine objects 
under the microscope. The asci are 8-spored, about 0024" long and :00075" broad. The 
paraphyses are agglutinated at the tips and indistinct throughout their length. 
18. L. cinerea, L.—Jakobshavn ; Kudlesæt ; in both cases on trap. Occurs in various 
* forms," some of them having the aspect of different ** species." 'The young thallus some- 
times consists of a series of dull lead-grey, pulvinate areolæ, resembling those of some 
forms of Lecidea atro-alba. The mature thallus is frequently uniformly white-granulose or 
farinose; and in this condition it generally gives a deep greenish-yellow reaction with 
potash. Other forms of the white mealy thallus, however, give a beautiful lemon-yellow, 
while some exhibit no reaction. The apothecia are sometimes lecanorine, with a distinct 
thalline margin, or lecideine and immarginate; very convex, flat, or urceolate. Some- 
times the disk is slightly white-pruinose as in Lecidea abietina. The urceolate forms 
are seated on or sunk in an areolate thallus—frequently of a leaden hue. Sometimes 
the apothecia are very minute in the young state and crowded, but always conspicuous. 
The lecideoid apothecia are sometimes as subspherical and prominent as in L. calcarea, 
into which cinerea undoubtedly passes by a series of gradations. In an intermediate 
stage between the lecanorine and lecideine apothecia, the disk is flat sometimes with a 
= 
thin, black, wavy margin. Between the forms bearing concave (urceolate) and convex | 
