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Trib. IIL—GRAPHIDACEI, Eschw., Nyl. 
Apothecia difformia, seepius elongata (lirelleeformia) excipulo 
proprio, aliquando indistincto. 
At first sight, Graphis, as exhibited in the tropics (and we might 
add Pyrenula, as here taken) appears well comparable with Thelotrema; 
and even in the feature which compels us to refer the latter (as compared 
both with Pertusaria and Urceolaria) to an extreme type of Parmeliacet. 
But, viewed more attentively, the large tribe before us is seen to be far 
less conditioned by the thallus; and to present unmistakable evidences 
of a quite inferior position in the scale of lichenose vegetation. Esch- 
weiler indeed (Syst. p. 13) degraded the Graphidacet (‘forma nimirum 
apotheciorum elongata, hinc minus perfecta quam concentrica, que vege- 
tationis summa est, &c., Lich. Bras. p. 65) to the very bottom of the 
Lichen-system; but Fries (LZ. E. p. 359) has vindicated for the tribe its 
now generally accepted place, as a deformation of the Lecidea-type; 
which, here as elsewhere, ascends, exceptionally, into lecanoroid 
expressions: Graphis being, in this view, to Heterothecium perhaps much 
as Opegrapha to Buellia. 
At one extreme, represented by Lecanactis and Platygrapha (Fam. 
Lecanactidei, Stizenb.) the Graphidaceous type reverts, even in form, to 
those of the two preceding tribes, and has, in this condition, been some- 
times associated with them: but the passage from such outlying groups 
into the true center of the tribe before us (Fam. Opegraphei, Stizenb.) is 
imperceptible; as is also that by which the compound Glyphidei, Fr., and 
the abnormal Arthoniei, Koerb., depart in the other direction. 
Of one of the two principal groups (both of the colourless series) 
constituting the Lecanactidei, almost a fifth inhabits extra-tropical 
regions, and, of the other, almost the whole. The Opegraphei, on the 
other hand, though represented, at one extreme, by some, mostly small, 
genera, a large proportion, and, in one case, two-thirds of the members 
of which are also northern, find their type in the great tropical group 
Graphis, of which only one-ninth reaches beyond the tropics. The 
proportion varies a little in the Glyphidei ; for though Glyphis be almost 
confined to tropical countries, a quarter of Chiodecton (of the colourless 
series) extends beyond. It is probably far from time to estimate 
Arthonia ; but, according to Nylander’s enumerations, while the genus is 
distributed more equally than others, the preponderance of forms is still 
in favour of the tropics. 
The elucidation of the spore-types is sometimes sufficiently embarrass- 
ing in the present tribe, but I incline to consider four-fifths of the species 
