(16 ) 
Nylander (in Prod. Fl. N. Gran. p. 14, not.) who observes in connection 
with this full revision of the plant that it makes no slight approach to the 
still embarrassed Cetraria tristis. A. Fremontii, Tuckerm. Suppl. 1,1. c. 
p. 422 (Evernia Lich. Amer. exs. n. 52) distinguished by its coarser, pitted 
thallus, and especially by its larger, yellow-pruinose apothecia (exceeding 
at length 3™™- in width) from filamentous conditions of A. jebata, passes 
yet into slender forms, which, if infertile, may readily be confounded with 
the older species. 
Usnea has often been regarded, and with justice, as constituting an 
extreme, and the highest, of Usneei; themselves recognizable as the 
highest extreme of Parmeliacei, as of Lichens. And though Alectoria in 
fact brings up the rear in the present, linear arrangement, it is by no 
means to be taken for (so to say) a descendant of Usnea. Much rather 
would we regard both groups as parallel lines of ascent to Evernia ; 
Usnea taking its departure from that modification of Evernia which begins 
in £. vulpina; and Alectoria, as represented by its principal type (.4. ochro- 
leuca) from E. Prunastri. But the centre of the family is shared with 
Evernia by Cetraria; and from the last we have in Ramalina a descend- 
ing line, in another direction, strictly analogous to Usnea; as in Roccella 
a sufficient contrast and tolerable counterpart to Alectoria. Unlike how- 
ever to Alectoria which we have supposed to constitute a distinct line of 
deviation from their common centre, parallel with Usnea, Roccella 
descends itself, it might seem, from Ramalina, and partakes with it, to 
at least a certain extent, in its peculiar analogy to Usnea. 
Fam. 2.—PARMELIEI. 
Thallus horizontalis, foliaceus, expansus (raro adscendus evernie- 
formis, rarissime alectorioides) cartilagineo-membranaceus, subtus 
normaliter fibrillosus. 
In nothing perhaps is the far too artificial character of the Method of 
Acharius more evident than in his attempted co-ordination of the genera. 
The remark is substantially Fée’s (£ss. p. xxi.) but this author, though 
he led the way in a more natural arrangement, and gave effect to the 
real affinity of Umbilicaria, left yet (Meth. Lich. in Ess. 1824) the Pelti- 
gerei between the Usneei and Parmeliei ; including also in the latter the 
genus Sticia. As Fries understood Parmelia (S. O. V. 1825. Lich. Eur. 
1831) no other disposition’ of the Peltigerei remained open to him; and he 
also arranged the latter between the former and Usneei. When however 
the sections of Parmelia, Fr., gained gradually acceptance as genera, 
some reconstruction of the relations of all these groups might well have 
been looked for; and had been in a measure anticipated by Fries himself, 
