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rock forms, but Segestria, as here taken, is also corticoline. The argument 
for the separation of Pyrenula from Verrucaria is based however on a 
difference of lichenose rank scarcely predicable of the Segestriei, in almost 
half of the species referable to which, the most of them corticoline, 
authors have recognized what we may call lecanorine analogies; and it is 
difficult not to admit that we have to do, in the latter, with a higher, and 
as respects at least the principal assemblage, a not indistinctly marked, 
natural group. 
LXIII.—SEGESTRIA, Fr. S. 0. V., p. 268. 
Segestrella, Fr. L. E. pp. 429, 460 (excl. S. rubra). Spharomphale exparte, 
Porina max. p., Thelocarpon, Thelochroa, Segestrella, Thelopsis, Micro- 
glena, Thelenella, Verrucarie spp., Geisleria, & Weitenwebera, Auctt. 
recent. 
Apothecia in verrucis thallinis immersa, perithecio colorato, 
amphithecio pallido 1. dein nigricante, paraphysibus capillaribus. 
Spore ex ellipsoideo oblonge 1. fusiformes, e simplici bi-quadri- 
pluriloculares 1. dein muriformi-multiloculares, incolores. Spermatia 
(quantum obs.) oblonga 1. acicularia; sterigmatibus simplicibus. 
Thallus crustaceus, effiguratus aut uniformis. 
After much consideration and many revisions of results, I shall venture 
here to set down what I believe to be a conceivable, and in several respects 
desirable interpretation of a group of lichens, the larger part of which 
has not yet been detected in North America; leaving it to others to 
give effect, so far as this ought to be done, to what is suggested. These 
lichens are certainly brought together by much agreement as well in habit 
as in the details of structure; but the application of all standards of 
judgment is especially uncertain in the Verrucariacei. It is however, if I 
do not mistake, the spore-characters upon which later arrangements of 
the types that make up the group largely rest; and the view to be taken 
in this place of the value of the arrangements in question, must depend 
therefore so far on our estimate of these characters. 
When first looked at, the group should appear to embrace types refera- 
ple to the colourless, as others referable to the coloured spore-series, as here 
taken; but the presumption is much against the exhibition of the former 
series in the present tribe; and there is no lack of instances, here as else- 
where, of decolorate conditions of the coloured spore. We may possibly 
find then, that, congruity in habit and general structure leading the way, 
the apparent diversities in the spore-structure shall explain one another, 
and what seemed typical distinctions prove only subordinate ones; gradal 
modifications of one and the same spore-type. The polysporous anomaly 
has elsewhere been touched upon, and I shall add only now that its rather 
remarkable presentation in the group before us is far from sufficient to 
