DR. LINDSAY ON WEST-GREENLAND LICHENS. 341 
into groups, often also becoming on their surface very irregular, sorediiferous, or granu- 
lar. Sometimes the thallus is inconspicuous, or appears to be altogether absent, the apo- 
thecia being scattered directly over the surface of various mosses, especially Racomitrium 
lanuginosum. In other cases the moss is coated only with an obscure thin white film ; 
or there are only a few isolated verrucæ. The spicula, which are the characteristic 
feature of the forms known as gonatodes and its allies, are thus developed :—The leaves 
of mosses become first covered with the thin, white crust of the lichen. In course of 
growth, this crust assumes the form of nodules or warts on the surface, spicula being 
protruded at its margins. The ends of the primary spicula are frequently the seat of 
‘minuter, secondary, divergent ones. Occasionally the spicula are so long and vermi- 
form, that the states of thallus bearing them might appropriately claim the designation 
vermicularia, resembling, as they do, moreover, certain conditions of Thamnolia vermi- 
cularis. | 
With potash, the young white smoothish thallus gives a beautiful lemon-yellow, 
becoming orange. With bleaching-solution, the same condition of thallus gives " bright 
blood-red reaction; as a general rule, all forms of thallus, including the muscicolous 
ones, developed a beautiful blood-red, or more brilliant crimson, or vermilion colour, 
slight attrition being required. The colour was most easily developed, and proved 
richest, on the denser, verrucseform states of thallus. In other cases, however, there was 
either no reaction, or it was very faint. Thus there was none with the young apothecia 
scattered, without thallus, over Racomitrium lanuginosum. With gonatodes, it was fre- 
quently very feeble, though at other times very brilliant ; while with the verrucæform 
sterile young thallus, there was sometimes no reaction, either with potash or bleaching- 
solution. Greenland forms of the type and of its varieties frigida and gonatodes yielded 
at once, under ammoniacal maceration, a port-wine-red colour—a result which I obtained 
also in Icelandie, Norwegian, and Faroese forms*. 
The apothecia are frequently very large, irregular in outline, and as if composed of a 
series of confluent individuals. They are also variously deformed by erosions or other- 
wise. I measured one old apothecium, which was nearly $" across. Sometimes new and 
smaller apothecia are developed on the surface of the old ones. Occasionally eroded 
portions of the hymenium are replaced by new tissue. Sometimes there is central 
erosion through all the tissues, or to various degrees, as in the apothecia of Parmelia 
perforata, the edges being generally very irregular, becoming thickened, and assuming 
the pale colour and characters of the thalline exciple. Where the hymenium disappears, 
the excipular subjacent tissue, which is of a whitish or cream-colour, becomes exposed. 
Where only part of the hymenium decays, the brownish red of the remainder contrasts 
euriously with the paler colour of the denuded exciple. The central parts of the disk, 
where not eroded, are frequently much areolate or fissured. The thalline margin 
(exciple) is sometimes very thin and inconspicuous, or it disappears, or is concealed by 
the swelling subconvex disk; in other cases it becomes greatly swollen and involute 
on the hymenium. Apothecia, both old and young, normal and deformed, occur some- 
times, apparently or really, by themselves, the thallus being either obseure or absent. 
* « Northern Lichen-flora,” Journal of Linnean Society, vol. ix. Botany, p. 415. 
