132 FIRST FORMS OF VEGETATION. 
loveliest of all our lichens, with its remarkably 
neat orbicular thallus of a snowy white colour, 
closely pressed to the stone, and plaited and 
lobed at the margin, contrasting beautifully with 
its central black apothecia, which, however, it 
rarely produces. 
There are three splendid foliaceous lichens found 
in Britain, whose proper home is in the Tropics. 
They are members of a family—the Stictas— 
which attains the largest size, the greatest beauty, 
and the widest distribution in the forests of South 
America, the West Indies, New Zealand, and in 
the South Sea Islands. Of the three British 
species, I found a solitary specimen of one, the 
Sticta crocata, on a mossy rock in the ‘ Birks of 
Aberfeldy.’ How it got there was a puzzling cir- 
cumstance. It is distinguished by the bright yel- 
low powder with which the tubercles or warts on 
the upper surface, and the little cavities among the 
down on the under sutface, are covered, and which 
is more abundant, and of a richer golden colour in 
New Zealand specimens. This lichen occurs in 
three or four places in Britain very sparingly ; but 
it has a very wide geographical range, being found 
on the mountains of New Zealand, in Jamaica, 
along the western slopes of the Andes, in the 
Sandwich Islands, down to the Straits of Magellan, 
and the Falkland Islands, in New Zealand, 
