(109 ) 
is described as similar in size and aspect to Lichen fusco-luteus, Dicks. ; 
and, if found in Scotland, may possibly have been included in his species 
by the British author; but an original specimen from the herbarium of 
the latter, in my possession, has the solitary, muriform spores of Hetero- 
thecium (Lopadium) and is the Lopadiwm fuscoluteum of Mudd (Man. 
Brit. Lich. p. 190) who first made the correction.——P. fulvo-luteum 
(Nyl.) is a smaller lichen, with the habit of P. sinapispermwm, and. is 
referred by Th. Fries, from whom I have excellent specimens, to the 
rather uncertain Lichen Jungermannie, Vahl. It occurs in Greenland 
(J. Vahl in Th. Fr. Lich. Arct. p. 121) and also in islands of Behring’s 
Straits (Mr. Wright).——P. sinapispermum (DC.) Hepp, resembling the 
last in the size of its darker, soon convex apothecia, has also been found 
in Greenland by Vahl, and in the alpine region of the Rocky Mountains 
by E. Hall.—P. rupestre (Lichen, Scop. Biatora, Koerb. Syst. L. calvus 
Dicks. Lecanora, Nyl. Scand. p. 447) the whole aspect of which, not to 
speak of the spermogones, refers it here, where both Fries, and Nylander 
have given it a place, differs yet, like P. fulgens, in its simple spores; and 
has not, like that species, afforded tolerably clear evidence of a more 
normal spore-structure. It is yet scarcely to be said that all indications 
looking towards the bilocular stage are wanting to the spores of this 
lichen, as compare Hepp. Abbild. t. 3,n. 7; more than sustained by what 
I observe in the spores of the American plant. This has occurred, on 
lime-rocks, in Vermont (Messrs. Russell and Frost) in the Helderberg 
mountains, N. Y. (Mr. C. H. Peck) and at Trenton Falls, N. Y. 
P. camptidium, Tuck. Obs. Lich. 1. 6. 5, p. 403, & 6, p. 287, is most 
commonly pseudo-biatorine, when specimens often resemble states of 
Biatora rubella v. spadicea, or may be passed over at length as convex 
conditions of Lecanora subfusca; and its range is southern, extending 
southward even to Cuba; but it is not uncommon in Southern Pennsyl- 
vania, and has recently turned up about New Bedford in Massachusetts 
(Mr. Willey).——F rom the last, P. diphasiwm, Tuckerm. Suppl. 1, 1. c., 
p. 426, occurring as yet only in Texas (Mr. Wright) differs in being 
always zeorine, and conspicuously in the colours, resembling rather Leca- 
nora varia. Both the species last named are associable with P. ferru- 
gineum, though differing so strikingly from it; but P. Floridanum, Tuck- 
erm. Obs. Lich. |. c. 5, p. 402, & 6, p. 287 (Florida, Mr. Beaumont ; 
Texas, Mr. Wright) which extends also to Cuba (Wright Lich. Cub. n. 111) 
recedes farther from common types, and reminds us rather of small forms 
of Rinodina sophodes. 
The present genus developes, as has already been seen, analogously 
with Lecanora; but its differentiation is less varied, and the subdivisions 
now far from as strongly expressed. I am still inclined to take P. cinna- 
barrinum (Ach.) Anz., which is common throughout the United States, 
as, equally with some rock-forms of P. aurantiacum (compare here 
Wright Lich. Cub. n. 114) representative of the Lecanorine section Aspi- 
