(218 ) 
demum et muriformi-multiloculares, fuscescentes ]. decolores. Sper- 
matia oblonga 1. bacillaria 1. acicularia; sterigmatibus simplicibus. 
Thallus crustaceus, wniformis, aut bypophleodes. 
The history of .Arthonia, as above sketched, sufficiently displays the 
uncertainties which have always embarrassed the group. One marked 
type, exhibited in 4. cinnabarrina (Coniocarpon, DC. Coniolome, Floerk.) 
has yet found general acceptance with lichenists; and has lost none of 
its instructiveness by its explanation (Scher. Spicil. p. 244; Koerb. 
Parerg. p. 264) through A. ochrucea. It was indeed with Chiodecton and 
Glyphis that Eschweiler (Syst.; Lich. Bras.) and Fries (S. 0. V.) placed 
Coniocarpon ; which both (in the works named) recognized as a compound 
type, conditioned, like Chiodecton, by a genuine stroma. Nor was even 
this inference, as we may well suppose, Without reason. 4. cinnabarrina 
and 4. ochracea, taken together, are well comparable externally with 
Chiodecton perplerum, Nyl. (elegantly exhibited in Lindig’s New Granada 
Lichens) no less in the earlier and simpler conditions (crowded at length 
into irregular patches) wherein a common margin, or stroma, is clearly 
discernible, than in the confluent, now stellate and now irregular clusters, 
deprived finally of any trace of excipular conditioning by the thallus, into 
which the apothecia of all these lichens finally collect themselves. Other 
examples of an often conspicuous thalloid margin are afforded by A. chio- 
dectella, Nyl., and 4. glaucescens, Nyl., as by our American specimens of 
A.impolita ; and it is scarcely doubtful that analogy should require us to 
assign the same (theoretical) value to the thalline conditions of the 
apothecia of Arthonia, as thus exhibited, that we assign to those of 
species of properly stromatous genera; or that Chiodecton is most closely 
akin (as compare also Massalongo’s observation, Ric. p. 149, already cited) 
to the Arthonia-group represented by A. cinnabarrina. 
But the lichen last named is an exceptional expression of Arthonia ; 
and, taken as a whole, the genus is rather marked by a general obsoles- 
cence of any marginal relation of the thallus, and in place of such margin 
(or presumable stroma) by that confluence of originally or theoretically 
proper exciples into an undistinguishable, and here almost structureless 
mass, which we hare above called pseudo-stroma. This deformation 
appears to be analogous to, and explicable in the same way with extreme 
conditions of the Glyphidei, as of medusuline states of Graphis.1 But 
the accompanying confusion of structure,—leaving only the thekes and 
their contents to redeem Arthonia from an internal obscurity as perplex- 
ing as its external,— though greater than in Chiodecton is yet in the same 
direction; as if to afford yet another indication that the genus before us 
1 « Sie quoque Lecidee nonnulle in formas simillimas abeunt apotheciis dimin- 
utis pluribus confluentibus.” Eschw. Bras. 1. ¢. p. 109. And this author fully 
distinguishes such symphycarpeous fruits, to be compared with those of Cladonia, 
from the proliferous ones so common in tropical Lecideei (Ibid. pp. 251, 257). 
