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obscurely sustained by analogous discrepancies in other tribes; as, for a 
single example, the Graphidacci. The instructiveness of A. tigillare is not 
however confined to the explanation possibly afforded by it of the lecano- 
roid wing of Acolium ; nor are we wholly without evidence of a tendency 
in the same direction, in the other wing. In New England specimens of 
the lichen just named, now before me, the thickness of the thallus being 
much reduced, the (full-sized) apothecia are largely denuded; and these, 
not expanding, as normally, into a patelleform shape, present rather a 
persistently conical one (observable also in young A. tympanellum) as if 
in anticipation of A. Javanicum (M. & V. d. Bosch) Stizenb. (Trachylia, 
Nyl., Tuck. Pyrgillus, Ny]. Syn.) while in others of the latter, commonly 
quite naked species, the larger part of the mature cone is covered, at 
times, and even conspicuously, by the thallus. 
The more or less crateriform apothecium of Calicium is anticipated in 
those species of Acolium (as A. tympanellum, &c.) which most nearly 
approach the genus first named. But in A. tigillare the proper exciple 
(well exhibited in Laur. Lich. in Sturm D. Fl. t. 32) is rather urn-shaped, 
and will possibly once more explain the extraordinary urn of A. Javani- 
cum ; the external difference of this last not being corroborated by any 
sufficient internal. In the remaining species, or at least the American 
ones, the proper exciple may also be described as crateriform. From 
this, 4. lewcampysz (Trachylia, Tuck. Obs. Lich. l. c. 5, p. 390; and in Wright 
Lich. Cub. n. 21) is yet to be excepted, the apothecia of this curious lichen, 
though in fact not ill-comparable with certain states of A. Javanicum, 
passing yet into oblong, now aggregated, and compound conditions, dis- 
‘tantly suggestive even of Graphidacei ; and, in particular, of Chiodecton. 
In some observations by the present writer on the genus before us 
(Obs. Lich. l. c. 6, p. 264) prominence was given to the pale apothecial layer, 
which originating on the one hand in a modification of the proper exciple, 
passes on the other into the thalamium. It was remarked that this layer 
exhibits itself externally, being traceable into the powdery inner margin 
of A. tympanellum and A. leucampyx ; and that it might deserve to be 
considered by itself. Further examination has tended to confirm this view, 
and even to suggest a stronger expression of it; that we have, namely, 
here, something analogous to the more or less distinct veil of Thelotrema. 
It is perhaps not clear how much this term, taken as it is to include as 
well the ‘interior exciple’ of the last-named genus, should properly cover ; 
but there is no doubt that authors have applied it to what appears com- 
monly, and may be described, as a kind of bloom, and—in this extent — 
it is equally applicable in the Caliciacci ; assuming the character even of 
an accessory margin in several species, of Caliciwm as of Acoliwm, and 
being further the remains, in these, of what has been a continuous exter- 
nal covering. And states may well occur in which greater compactness 
shall give this covering a fair title to be called membranaceous; if indeed 
the two forms of Tylophoron, Nyl., do not sometimes furnish such indica- 
