(41) 
Fam. 5.—PANNARIEL. 
Thallus horizontalis, frondoso-foliaceus dein multifidus 1. squamu- 
losus, coriaceo-membranaceus, hypothallo pannoso demum evanido. 
Stratum gonimicum indolis varie; e gonidiis viridibus (solitis) aut, 
sepius, cerulescentibus (collogonidiis) constans. 
If we have really reached, in the Peltigerci, the summit of Parmelia- 
ceous lichens, it cannot surprise us to meet next with another group, at 
once approaching the former in essential structural characters, and yet 
shewing marked evidence of degradation. And this is exactly what is 
indicated by the Paunnariei ; or, to cite only, for the present, the chief 
member of the group, Pannaria. In both alike of its principal sections, 
determined significantly, as in most of the genera of the Peltigerei, by 
the twofold structure exhibited by the gonidia, this genus displays the 
foliaceous thallus, disappearing finally in what is only not the crustaceous. 
One of the noble, austral forms of the section distinguished by green gonidia 
(Psoroma, Nyl.) has much of the port at least of Peltigera canina ; but 
the only northern representative of the group is the semi-crustaceous 
P. hypnorum. Of the other section, in like manner, in which blue- 
green gonidia (gonimous granules, Nyl. collogonidia, nob.) replace the 
ordinary type of these cells (Pannaria, Nyl.) we have on the one hand species 
(P. molybdea, plumbea, Gayana, fulvescens) comparable with Sticta, and 
yet on the other, and associable with the first by unquestioned affinities, 
forms not only not foliaceous, but even, finally, in the opinion of almost 
all lichenographers of the present day, not even lichenose. And this 
brings us to the most interesting chapter in the history of Pannaria,—that 
which concerns its relations to Collemaceous lichens. 
It will hardly be doubted that even Sticta is brought into peculiarly 
close, relations with Collema, etc., by its blue-green gonidia; and Fries 
was well able to compare with it (in Mallotiwm, Ach.) such Collemaceous 
plants as Leptogium Hildenbrandii and L. Menziesit. But the affinity of 
the latter to Pannaria is evidently far more intimate. The two groups 
plainly touch at several well-ascertained points ; and there are not a few 
forms now actually in question between Lichenes and Collemacee: thus 
abundantly illustrating the justness of Koerber’s remark that the divid- 
ing line between Collemaceous and true Lichens is by no means so sharply 
drawn, in nature, as we have drawn it (‘dass die Scheidewand 
lange nicht so scharf gezogen sei, als wie wir sie gezogen haben.” Purerg. 
p. 26). If, following the indications of habit, we compare, with the 
microscope, the thalline structure of Pannaria lurida, Nyl. (Collema, 
Mont. Parmelia (Amphiloma) Russellii, Tuckerm. Syn. N. Eng.) with 
that of species of Pannaria externally not dissimilar, it seems impossible 
to refer the former to any other genus: P. fulvescens (Mont.) Nyl. (Herb. 
Mus. Par.) sufficiently mediating, in its perhaps rather lax medullary 
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