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of differentiation, the original group has passed now into near a dozen ; 
representing Pannaria analyzed. It is impossible, however, that this 
should be the end; and the grave differences of opinion among lichen- 
ologists as to the value and limitation of these clusters, —what is Pan- 
naria with one becoming Coccocarpia with another, what is Plerygium 
with one, Lecothecium with another, and what is Lecothecium with one, 
Pannaria with another,—point not uncertainly to a future reunion of 
the sundered types; when the long lost idea, ennobled by the rich results 
of study, shall once more be recognized in its integrity. 
The preliminary observations sufficiently shew that the present writer 
jis, for his part, unable to adopt the opinions of those lichenographers who 
have elevated the anomalies of Pannaria into generical, and even ordinal 
distinctions. To do this is to disregard the natural connection and even 
continuity of most intimately related clusters of forms; a fact tacitly 
admitted indeed by the most experienced of modern lichenologists, as 
well in his observations on the relations of his Psoroma and of Coccocar- 
pia to Pannaria proper, as in those on the affinity of P. nigra (Lecothe- 
cium & Collolechia, of authors) to Pterygium ; and if he has recognized 
as sufficient the unsatisfactory difference which should separate the lat- 
ter, this cannot destroy the value of his testimony as to all the former. 
Psoroma, Nyl. (Disp. Psorom. d: Pannar.) embraces almost the whole 
of the Pannarie, of other authors, the gonimous system of which exhibits 
the normal structure of the Parmeliacei. Represented at the north only 
by the squamulose P. hypnorium,—the apothecia of which none the less 
interestingly exhibit the genuine Parmeliaceous type, so soon to disappear 
in the succeeding sections, accompanied also, in the var. paleacea, with 
other features of resemblance to Sticta, recurring there, —this group 
developes, at its centre, in the austral regions of the earth, into conspicu- 
ous, at length frondose-foliaceous forms, well worthy of its position as the 
highest extreme of Pannuria ; looking towards Sticta, and the Parmeliei. 
P. lanuginosa (Ach.) Koerb., the fruit of which is, at present, quite 
unknown, offers little to connect it with Psoroma beyond similar gonidia. 
From these recedes Pannaria proper, conditioned, sometimes most 
perplexingly and in a manner unknown to the similarly receding groups 
of Peltigerei, by the seemingly abnormal structure of its gonimous system; 
and no less by its frequently pseudo-biatorine fruit. It is observable 
however, that the section before us is mainly lecanorine, as respects its 
best developed species; and that it is the reduced forms which in this, as 
in other respects, anticipate the various irregularities of the next. The 
highest cluster, or that more immediately represented by P. rubiginosa, 
is best exhibited in the tropical P. pannosa, and, especially, in the 
Polynesian P. fulvescens (Mont.) Nyl. The latter is unknown to North 
America; but P. pannosa reaches, seen as yet only infertile, the low 
country of South Carolina (Ravenel) and Louisiana (Hale) and, in the 
tropics at least, is very evidently, not to say more, to P. nigro-cincta 
