( 84 ) 
save only in the extreme case, already repeatedly referred to, of O. phyl- 
lisca (Phylliscum, Nyl.). 
But this plant, if well-comparable as respects its collogonidia with 
species of Synalissa, is yet in no other respect than the size of these or- 
gans separable from recognized types of Omphalaria, with which group 
it obviously better agrees in its foliaceous thallus; and being thus and to 
this extent clearly Collemeine, the presumption that its fruit shall be 
explicable from the same standpoint is as strong, as in any other case in 
which this explicableness is admitted. Nor in fact is the fruit really in 
the way. A certain form of anamorphosis being given, we should expect 
this modification of structure to reach at length its full exemplification. If 
all the other conditions of inexplicate apothecia before us are admissible as 
abnormal gymnocarpous types, the present can hardly be refused admis- 
sion into the same category because simply the anamorphosis is here com- 
plete, and the wholly immersed disk becomes, as of course it must, no 
longer imperfectly, but perfectly nucleiform. O. phyllisca (Nyl. Syn. t. 
3, f. 5) diverges no further from O. phylliscoides, Nyl., (J. c. f. 3) in this 
regard, than it were beforehand presumable, from the point of view of 
the latter, that another species should possibly diverge; and there is in 
short no other appreciable difference than what depends on this final 
completion of the process of reduction; of which we need not go beyond 
the present genus to find every other step. We cannot then speak, with 
Massalongo (Neag. p. 7) of a double exciple in O. phyllisca, without 
admitting the applicability of the same term in the case of other species, 
the understood character of the anomalies of which makes it impossible; 
nor of an amphithecium without the same consequence. 0. leptophylla, 
Tuck. (Wright Lich. Cub. n. 1) is, I take it, admissibly an Omphalaria; 
and yetit is not without interest that this lichen has also been referred, and 
by authority so high that its citation is an element of value in this dis- 
cussion, to Phylliscum. Even more similar, as well in colour as especially 
in the depressed apothecia opening equally by a pore-like aperture, is the 
Cuban O. deusta, already elsewhere described. And there is yet another 
new lichen, the significant relation of which to O. phyllisca can hardly be 
passed over. To refer the crustaceous Synalissa phylliscina to Phyllis- 
cum, Nyl., we must disregard that important distinction in the thallus 
upon which the very existence of Synalissa and Omphalaria, as separate 
groups, depends; and it is certainly no easier to elevate it to the rank of 
a genus. If then the Synalissa belong where we have placed it, why 
should not the type of Phylliscum be referable to Omphalaria? 
Like Synalissa, Omphalaria has always been taken to be characterized 
by simple spores. Evidence of probable exceptions to this rule has how- 
ever been given by Nylander, in the case of the former genus; and may 
well yet appear, as respects the latter. Collema elveloideum, Ach. (Nyl. 
Syn. p.116. C. phylliscinum, Nyl. Prodr., fide auct.) in which the spores 
are described as bilocular, cannot but approach very closely to Ompha- 
laria, as here understood. 
