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Trib. IJ.—LECIDEACKEI, Fr. 
Apothecia libera, rotundata, patelleeformia, aperta, dein et hemi- 
spheerica globosave cephaloidea; excipulo proprio; thallino normal- 
iter nullo. 
The important part filled by the thallus in the Parmeliacei is conspic- 
uous also in the (at least ideally) always present thalline receptacle of the 
apothecium. But, in the present tribe —otherwise now sufficiently resem- 
bling Lecanorei, and now not ill comparable with Usneei— this thalline 
border is deficient; and the hymenium is bordered only by the proper 
exciple: a rule not invalidated by sundry exceptions (as Béomyces eru- 
ginosus, Buellia albo-atra, &c.) in which the apothecium is conditioned 
also extraordinarily by the thallus. The two tribes differ then, to use an 
expression of Acharius (Meth. p. 32) ‘ quantum patellule a scutellis disce- 
dant” And this originally patelleform type of fruit, characteristi®al of 
Lecideei, and often called biatorine, is predicable equally of Stereocaulon 
and Cladonia; which genera are scarcely in fact to be well separated 
from Biatora, but by the thallus. 
There is really nothing to distinguish the crust of. Beomycei and 
Lecideei from that of Lecanorei: but the thalline evolution of Cladoniei, 
— combining as it does, especially in Cladonia, together with biatorine 
apothecia, both the horizontal and vertical types of thallus—is so 
Tremarkable, that we can hardly avoid allowing it an influence on our total 
estimate (as compare Fr. S. 0. V. p. 247) of the tribal characters ; 
whether or not, with Eschweiler (Lich. Bras. p. 240; followed herein by 
one or two others, as, according to Th. Fries, by Massalongo, and by the 
present writer in Syn. Lich. N. Eng.) we go so far as to regard it, in some 
sense, the highest expression of lichenose vegetation. 
The position of Canogonium is uncertain: but the constitution of the 
thallus forbids its association with Collemei; while the apothecia are evi- 
dently biatorine. Is it possible then to conceive of it as occupying, in 
the present tribe, a position analogous to that of Pannariei-Collemei (to 
look at these for the moment as one) in Parmeliacei? Canogonium will 
in that case interrupt the natural contiguity of Cladoniei and Lecideei ; 
but only as Pannaria, &c., interrupt that of Parmelia and Lecanora. 
The tribe is a large one, and though much smaller, in the number of 
species, than the Parmeliacei, greatly exceeds this, in the colder and 
especially the arctic regions of the earth, in the number of individuals; 
Cladonia being as remarkable in this respect, as it is also for its variable- 
ness. “‘ Nulla certe vegetabilia,’ Nylander remarks of this genus (Syz. 1, 
p. 188) ‘copia majori et lutius distributa inveniuntur.” 
