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exciple is wholly black, or ‘entire,’ (G. assimilis, Nyl.) if less common 
than the other, occurs, at least, in so many of the marked varieties of the 
species, that it may perhaps be presumed to occur in all; and G. analoga, 
Nol. (Lich. exot.1.c. p.244) as described, should seem to be scarcely more 
than an analogous condition of one of the similarly variant, and other- 
wise undistinguishable forms of G. scripta, with spores now finally muri- 
form (G. sophistica, Nyl.). 
Of the next succeeding group in Nylander’s disposition of the genus, 
the typical species is G. dendritica. The exciple of this is, more com- 
monly, wholly black, or ‘entire’; but forms, in all other respects similar, 
and exhibited in a precisely similar series of variations, frequently occur, 
in which the hypothecium is colourless below (G. inusta, Ach., Nyl., 
G. Smithii, Leight.) as in the ordinary states of G. scripta ; which thus 
illustrates, in this phase of variation, and is illustrated by, the present. 
But the peculiar line of development of G. dendritica is sufficiently 
marked; its dilated exciples now offering rounded conditions, comparable 
rather with Lecanactis (to which such conditions have in fact been 
referred) and the Lecideei ; and now passing into confluent ones (Medusula, 
Auctt.) reckoned at first even alien to the tribe. It does not at least 
appear to me to be questionable that the North American G. dendritica 
passes directly, in both its ‘entire’ and ‘dimidiate’ states, into genuine 
Medusule of authors. Ustalia, Fr., Eschw., pro p., aremarkable tropical 
cluster of species, with flat, reddish disks, is not only near to the group 
represented by G. dendritica (as compare Fr. L. E. p. 373) but perhaps 
not easily, in any wide view, if we deny stress to biatorine analogy, to be 
separated from it. There seems to be no more reason for distinguishing 
the Ustalie, properly so called, from the Graphides dendritica, than for 
separating, generically, the coloured or colourless species of the next 
succeeding group from those with black exciples; as, for instance, 
G. chrysenteron, Mont. (Leucogramma, Mass. Esam.) or G. hololeuca, 
Mont. (Glaucinaria, Mass.) from G. Afzelit, Ach. (Diplolabia, Mass.). 
Fries, at first (S. 0. V., with which compare Z. £. p. 373) referred 
G. Lyeliii, of our last section, to his Graphis ; the type of which was 
G. Afzelii. But interesting as is this indication of apparent affinity in the 
two sections, we have only to look at the species last named when denuded 
of its white vesture, to incline to place it, with Eschweiler, not in his Leior- 
reuma, with G. Lyellii, but rather with G. comma and G. intricata, in his 
Graphis. And there isno doubt that the great, central group of Graphis, 
now before us, of which G. Afzelii has been regarded by some writersas rep- 
resentative, as is G. frumentaria, Fée, by Nylander, takes hold at once of 
both of the preceding groups, and exhibits the summit of development 
to which the genus attains. It is here too that lecanoroid features become 
especially marked, and that Thelotrema is so plainly touched, that it 
appears doubtful to which genus certain species shall be referred. Like 
the Ustalig, the group is a wholly tropical one, though extending here 
