988 Lichenes of New England. + 
pulverulentus, Schreb. ; & P. = Ach. Meth., 
cum Ic. (sec. Spreng. ), nec Hals. I. c., Mass. Catal. — 
Bark of trees; Cambridge, and elsewhere ; a not un- 
common and handsome species.. The P. venusta, 
Ach., seems, by the cited, description and figure, to 
be too nearly allied to this species, with which it is 
united by, Sprengel. In P. pulverulenta, the bor- 
der of the scutelle is described as either entire; Or 
notched, or quite leafy. 
P. speciosa, Ach. Meth., Scher.! 1. c., Spreng. l. 
c., Hook. l.c., Muhl. 1. c. — Rocks in old woods, 
Waltham, Medford : trunks of trees, not very general, 
Cambridge, Watertown; New Ipswich, N. H. Spren- 
- gives a habitat of this species in Boreal America, 
„Muhlenberg enumerates it in his Catalogue. It 
ps, especially. i in the finely fruited state (un- 
known in Great Britain), in which I have almost — 
always found it, the most beautiful of. our Parmelie. 
Hooker describes the lobes of the thallus as powdery 
at the extremities; but Acharius remarks, that. they 
are sometimes naked: the latter is the most common 
state in our plant. It would seem, from the descrip- 
m tion given in Eaton’s Manual, of one or two species, 
which are named as new species in Muhlenberg’s Cat- 
alogue, that our plants (and especially the saxicoline 
form) are very nearly allied to these; but I am unable, 
at present, to ascertain this, by the necessary com- 
parison of specimens. 'The’saxicoline plant belongs 
o P. speciosa, unless it be found to differ sufficiently 
to form a new species; but the other, which I havé 
mentioned as growing on trees, may, I think, prove 
distinct. Both, however, are nearly related to P. 
speciosa. . 
