(203) 
cited above only those writers the scope of whose observations embraces 
the whole genus. It will be readily seen how various have been the 
judgments upon it. The acuteness of Eschweiler led him indeed into 
discriminations in the present tribe, especially in Graphis, and Opegrapha, 
which have not been followed; and some of which he abandoned himself. 
Others, as Fries, have questioned the validity of distinctions, which yet, 
with the insufficient material before them, they did not wholly reject. But 
it was left to Nylander to revert to the simplicity of Acharius’s conception ; 
and, in fact, to found Graphis, enriched now with a vast accession of 
forms, anew. 
The lecanoroid character of the large group before us, becomes at 
length marked in many tropical conditions, and easily influences its 
separation from Opegrapha, though the feature is finally indistinct ; but 
there can be no doubt that Graphis touches Thelotrema, and is illustrated 
by the latter at least equally multiform natural genus; as also by the 
lecanoroid group of Biatorei (Heterothecium). The variations in colour 
of the very commonly concealed proper exciple of Thelotrema have 
scarcely received the attention that has been given to those of Graphis, 
but there is no doubt of their occurrence ; and the generical inseparable- 
ness of such varying conditions of the former genus from each other, may 
well influence our judgment of the exceptionally coloured or entirely 
colourless exciple (as, for example, in the clusters once separated as 
Ustalia, and Fissurina, by authors) in the latter. In neither of these 
genera, nor in Arthonia, does it appear that we can (ceteris paribus) 
separate generically biatorine from lecideine types ; however natural and 
convenient such discrimination be in the Lecideei. 
The large group of species represented by G. scripta and G. elegans, 
approaches so closely to Opegrapha as at length to be only distinguishable 
by the spores; and the group is referred to Opegrapha by Fries and 
Montagne; as it was also united with Opegrapha, under Graphis, by 
Meyer; and, latterly, by Eschweiler. It recedes, however, from the other 
type, not merely in the more or less conspicuous thalline margin, but 
further in what must be called a tendency to modification of the proper 
exciple; this being, largely, colourless below (perith. mere laterale, Eschw. 
Excip. propr. incompletum, Fr.). The latter distinction is, notwith- 
standing,-to say nothing more, an uncertain one; and the clusters of 
forms exhibiting it afford also, not seldom, complete evidence of a return 
to the wholly black exciple (perith. integrum, Eschw.) thus leaving little 
but habit, and the internal characters, to connect the group with Graphis, 
ashere taken. Every stage, if Imistake not, in the gradual transformation 
of the ‘merely lateral’ into the ‘entire’ exciple may be observed in the 
universally distributed G. scripta ; and notwithstanding the great author- 
ity of Nylander in the present tribe, it is no more easy to follow him in 
elevating the difference in question into a specifical distinction, than 
Acharius, in taking it for generical. The state of G. scripta in which the 
