350 DR. LINDSAY ON WEST-GREENLAND LICHENS. 
beautiful lemon-yellow. Like cinerea, it occurs in several forms; but it is far from 
being so variable. In one form (Kudleset) the apothecia are slightly white-pruinose, 
black, irregular in outline and surface, sessile, flat or more or less convex. The sporidia 
are simple, colourless, oval, :0003” long and :00022" broad. In what appears to be 
simply another condition from the same locality, the sporidia are smaller, oblong, or 
ellipsoid; the apothecia flat, regular in outline, with a distinct exciple. The appearance 
of these two forms is very different—nearly as much so as it is different from the asso- 
ciated urceolate forms of cinerea. All the forms described here, under both cinerea and 
calcarea, appear to me to be properly referable to a single type. In Central Europe Le- 
ciographa parasitica, Mass. (Korb. * Parerga, p. 463), is sometimes parasitic on the 
thallus of calcarea. 
15. L. leucorea, Ach. About the Illartlek glacier, both terricolous and muscicolous ; 
Jakobshavn. This plant seems to me referable to Z. ferruginea, which is more pro- 
perly to be regarded as a Lecidea than as a Lecanora—the exciple, where it exists, having, 
usually at least, the same colour as the disk. | 
Genus 19. LECIDEA. 
Even to a greater extent than Lecanora does, the genus Lecidea illustrates the ten- 
deney of the modern or Continental school of lichenologists to split up the generally 
excellent genera of the Acharian era into subgenera, founded on the too frequently 
variable characters of the sporidia. Differences in the character of the sporidia, when 
constant, and especially the degree to which their contents are divided into loculi by 
septa or interspaces, may be and are useful, in large genera like Lecidea and Lecanora, in 
subdividing them into sections or groups. But it is not, I think, desirable to give these 
sections generic importance or rank. This elaboration, which appears to me (as I have 
elsewhere explained) unscientific and unnecessary, is sufficiently exhibited in Th. Fries's 
* L. Arctoi,’ who classes the arctic Lecidee under the following separate genera * :— 
(1.) Lecidea. Apothecia black. Sporidia 8, simple, ellipsoid, colourless. 
(2.) Thalloidima. Apoth. Lecideine. Sporid. 2-locular, ellipsoid, colourless. 
(3.) Buellia. Apoth. Lecideine. Sporid. oblong, 2- to 4- or multilocular, brown. 
(4.) Rhizocarpon. Apoth. Lecideine. Sporid. oblong, 4-locular to muriform, brown. 
(5.) Arthroraphis. Apoth. Lecideine. Sporid. acicular, multilocular, colourless. 
(6.) Rhexophiale. Apoth. Lecideine. Sporid. fusiform, 4-locular, colourless. 
(7.) Biatorina. Apoth. variously coloured, not black t. Sporid. 2-locular, colourless. 
(8.) Biatora. Apoth. Biatorine. Sporid. ellipsoid, simple, hyaline. 
. (9.) Psora. Apoth. Biatorine. Sporid. linear, 4- to multilocular, colourless. 
(10.) Bilimbia. Apoth. Biatorine. Sporid. oblong, 4-locular, colourless. 
(11.) Blastenia. Apoth. Biatorine. Sporid. polari-2-locular, ovoid, colourless. 
* Restricting these illustrations—as in the case of the genus Lecanora—to sub-genera represented in Greenland. 
_ + The distinction between brownish or reddish, and black, apothecia in Lecidea is far from being constant or satis- 
factory. Illustrations of the inconstaney of this character may be found in the Greenland forms of L. parasema, 
L. sanguineo-atra and L. Friesiana. There is therefore no good (scientific) ground for separating Biatora and 
Lecidea as genera. 
