of Four New Brit Lichens. | 285 
lour, and, with an inattentive obferver, might pafs for different 
fpecies. Its ftate of perfection is that defcribed in the differentia 
Jpecifica, when the ground is a fine polifhed white, and the frusti- 
fication a bright fhining black, with a white margin, fig. A. In 
its fecond ftate, it lofes that gloffy black, fig. B. In its more ad- 
vanced ftage, it becomes ftill paler; and in this ftate I have feen it 
in a collection under the name of L. rupicola, fig. C. As it ap- 
proaches nearer decay, the ícutelle affume an ochreous or buff- 
colour, very different from either of its former appearances, fig. D. 
In its laft ftage, which I had not obferved till after the inclofed 
drawings had been made, it affumes a ftill very different appearance; 
the difks of the ícutelle difappear, and there fucceeds a black 
duft, giving it in fome meafure the refemblance of a fphæria. 
The fingularly-various appearances of this plant afford an oppor- 
tunity of obferving how liable períons are to be deceived by plants 
of this tribe, whi ich. they have anot an opportunity of examining in 
their places of growt! h; | may ferve as a caution, that our zeal 
for difcovering new fubjeéts fhould not hurry us to create new 
fpecies out of imperfect fpecimens. 
Found on the S. W. fide of Anglefea. 
XXVIL An 
