(86) 
blastus, et Collema, Arn. Lich. Fragm. in Flora Ratisb. 1867, n. 8-9, 
t. 1-4. 
Structuram exposuerunt Tulasne, Mém. pp. 28, 45, 64, 178, t. 6, 7; 
Schwendener, Untersuch. 1. c, 3, p. 153, 4, p. 185, t. 22. 
Apothecia scutelleformia. Spore ovoideo-ellipsoide, 1. simplices, 
1. dein fusiformi-elongate bi-pluriloculares, 1. muriformi-plurilocu- 
lares, Sub-incolores. Spermatia ellipsoidea oblongave; sterigmatibus, 
in plerisque, articulatis. Thallus foliaceus aut rarissime fruticulosus; 
strato corticali plerumque nullo 1. indistincto; collogonidiis fere 
semper moniliformi-concatenatis; filamentis medularibus conspicuis, 
laxis. 
We reach, in Collema, not indeed the highest expressions of lichenose 
vegetation afforded by Eucollemei, but certainly the central and most 
typical representatives of the group. Here all the peculiarities of Colle- 
meine structure find their best exhibition; and so marked at length is the 
development of mucilage and its conditioning influence upon the thallus, 
that even the unquestioned Parmeliaceous affinity indicated in the 
apothecia has proved insufficient, in the opinion of a majority of authors, 
to assure to these plants a place among ‘true Lichens.” It is not how- 
ever too much to say that instead of confirming the judgments of those 
writers who make of Collemei a separate Order, the best later research 
has in fact tended to invalidate these judgments; and if there now 
remain any clearly sufficient ground for the exclusion of the jelly-lichens 
and what go with them from that place in the system to which they 
should be referred by their fruit-characters, it is at least unknown to the 
present writer. 
The well-marked difference of these lichens was still not one to 
escape attention; and when Dillenius (Hist. Musc. p. 137, t. 19, f. 19-35) 
had contributed, as he did, above all others who had preceded and many 
who followed him, to their elucidation, it was not long in finding expres- 
sion in a generical name (Collema, Hill, 1751) which, taken up, long after, 
by Schreber (in Linn. Gen. Pl. 1791) and provided with a character, pre- 
pared thus a way for the special labors of Hoffmann (D. Fl. 2, p. 98, 1795) 
and finally of Acharius. Some writers indeed among those who suc- 
ceeded the latter, as Wahlenberg, Meyer, Wallroth, and Scherer, in his 
principal work (Spicil. p. 511) declined to recognize in Collema anything 
higher than a section of Parmelia ; but Eschweiler’s careful review (Syst. 
Lich. 1824. Lich. Bras. 1. c. p. 231) and justification of the distinctions 
of the group, undoubtedly better expressed the opinion of the time. 
This was in fact now ready for a more searching analysis; and Fries’s 
limitation of Collema by the exclusion from it of Thermutis, Synalissa, 
and Leptogium (S. O. V. 1825, p. 255, where the Dfallotia appear also to 
be within the author’s view) determined at length the course of subse- 
