(43) 
of some Collemacee, is perhaps better explained by another American 
lichen (Pannaria flabellosa, Tuckerm. Obs. Lich. 1. ¢. 5, p. 401) not readily 
removable from the same family, or even the same genus with P. trypto- 
phylla. Itis evident here that the writer is unable to adopt Nylander’s 
estimate of the value, as a structural difference, of the indistinctness or 
even obsolescence of the hypothallus, in his Pterygiwm. 
The indications afforded by the family last preceding of a disappear- 
ance of the thalline exciple, find their complement, in the present, in 
pseudo-biatorine forms, which considered apart from their obvious con- 
nections, should be referable to the Lecideacei. Coccocarpia, Pers., Mont., 
constituted, it is probable, by only the varying forms of a single species 
(Tuckerm. in Wright Lich. Cub. n. 104-107) is without doubt to be 
referred to the number of such pseudo-biatorine Pannari@ ; a conclusion 
suggested by if not involved in Nylander’s reference of P. pluimbea to 
Coccocarpia. 
Psoroma, Nyl., only differs from Pannaria of the same author, in the 
structure of its gonidia; but his more recent reference of the former to 
Lecanora (Lich. N. Zeal. in Journ. Linn. Soc. Lond. 9) hardly sufficiently 
takes into account its well-marked habit. The tropics furnish us, how- 
ever, with two other remarkable types, neither of them wholly alien to 
Pannariei, and both characterized by green gonidia. One of these (Par- 
melia gossypina, Mont. Wright Lich. Cub. n. 110. Crocynia, Mass. 
Esam.) is associated by Nylander with the still doubtful Lichen lanugi- 
nosus, Ach., in Amphiloma, Nyl.; but recedes remarkably in its byssus- 
like thallus, and in the habit of the apothecia is not ill-comparable with 
Heterothecium Domingense. The other, Physcidia, Tuckerm. Obs. Lich. 
l.c. 5, p. 899 (Wright Lich. Cub. n. 92, 93) combines a thallus now like 
that of some Physcia, and now resembling rather a squamulose Lecanora, 
with a byssoid hypothallus, comparable with the thallus of Parmeli« 
gossypina, composite (zeorine) apothecia with much of the aspect of 
those of Pannaria sphinctrina, Mont., and acicular, quadrilocular spores. 
Heppia, Naeg., referred to the present family by Nylander, appears 
finally to agree with it in some particulars of habit, as it does also in 
internal characters. The proximity of the Pannarici to the Peltigerci is 
illustrated by this little lichen, referred by other authors, without excep- 
tion, to the near neighborhood of Solorina ; and perhaps even more evi- 
dently by Frioderma, Fée, here placed with Peltigere?, but by Nylander 
with Pannaria. 
It has been stated elsewhere that the whole manuscript of this 
arrangement of Parmeliaceous lichens was completed, essentially as it 
now stands, before the researches of Professor Schwendener on the 
anatomy of the thallus had, in any form, become known to the writer. 
The passages cited below of a portion of the German author’s general 
observations on the family now before us, and on its close relations to that 
next to follow, are therefore pertinent; and I add here a rough outline, 
