(255 ) 
differentiation of the (normally) coloured type. And the same remark 
holds good of Thelopsis ; T. inordinata, Nyl. (Lich. Kurz. in Flora Ratisb. 
1867, p. 9) differing mainly, it should appear, from T. rzbella, in the spores 
being ‘not regularly 3-septate, but exhibiting also oblique or longitudinal 
dissepiments’; or as Geisleria with submuriform spores from the same 
type with regularly 4—locular ones. 
Thus far the Lichen-clusters considered, with the exception of the 
muscicoline Thelocarpon coccophorum, and Thelopsis, are confined to 
inorganic substrates, or, at least, known only as parasitical; and, taken 
in connexion with a specific type yet to be noticed, might be considered 
as bearing a similar relation to Verrucaria, as, in that case, the remaining 
corticoline members of Segestria would bear to Pyrenzla, in the Pyrenulei. 
The European Thelocarpa would then be to Thelopsis, much as Segestrella, 
Koerb., to Porina, Mass. But the difficulty in distinguishing generically 
the saxicoline and corticoline series in the Pyrenuici is greatly increased, 
as already suggested, in the higher group before us; and there certainly 
seem to be no characters, or no sufficient ones, for the purpose. Thelopsis, 
Nyl. (Segestrell@ sp., Zw. Sychnogonia, Koerb.) is in fact a corticoline 
Segestrella, further differenced by polysporous thekes ; and the argument 
here from general structure will not readily yield to any yet drawn from 
the structural anomaly noticed. 
Scarcely more distinct in aspect and less so in details is the tropical, 
corticoline group represented by Segestria nucula, Fr. (Porine sp., Ach.). 
The marked lichenose features of this group have been recognized by 
almost all lichenographers who have considered it; but differences suffi- 
cient for its separation from the section Segestrella do not appear. 
We found the habit of the last-named, saxicoline section exhibited, as 
well in the corticoline Thelopsis, as combined with entire agreement in 
structural details in Porina ; and it now remains to recognize in a lichen 
from the lime-rocks of the island of Cuba (Mr. Wright) what might well 
be taken for a saxicoline Porina, did not the spores (the differentiation of 
which has here at length fully reached the muriform stage) denote it 
rather a rock-Thelenella. The description of the manifestly Segestriine 
Verrucaria thelostomoides, Nyl. Pyrenoc. p. 41, from which the learned 
author himself says that his V. lwridella, from Bolivia, ‘scarcely differs,’ 
leaves nothing to be desired in its application to this Cuban lichen, and I 
cannot therefore venture to distinguish the latter; which mediates, it 
should seem, on the one hand, between Porina and Segestrella, and com- 
pletes, on the other, the evidence of Geisleria as to the true spore-type of 
the whole group. 
The noticed specimens from Cuba of what is probably to be called 
Segestria thelostomoides agree still further with the corticoline Thelenella, 
Nyl. (Microglena, Koerb.) of Europe, in the contents of the spermogones ; 
the spermatia of the former being needle-shaped and bowed, and borne 
