( 22 ) 
(Lindig Herb. N. Gran. n. 799) as well as in a corresponding condition 
of P. tiliacea (v. flavicans, Tuckerm. in Wright Lich. Cub. n. 74). And 
what is possibly quite as remarkable is the similar change of color of the 
medullary tissue in P. sulphurata, Nees and Flot., P. aurulenta, Tuck- 
erm., and P. isidiocera, Nyl. —— The evrernioid rerergence of this subdi- 
vision is observable also in P. perforata ; which, in the var. cetrata, Ny1., 
passes, more or less, into narrowed, many-cleft, channelled lobes, compar- 
able often, apart from their type, with nothing but P. Camtschadalis —— 
And it is with the same extreme type of Parmelia that one is tempted to 
compare the elongated, lax forms of P. physodes. That this species is 
near akin to P. colpodes (Anzia, Stizenb.) cannot well be denied; but the 
anomalies and contradictions of the cluster, so constituted, are unexam- 
pled in the genus. 
But the accumulation of marked features which distinguishes the 
group here typified by P. levigata is not yet complete. P. saratilis and 
its nearest allies belong to the group: and, in a well-known, alpine con- 
dition of the former (v. omphalodes, Hoffm.) it passes also into the brown 
series; now very briefly to be considered. We have here, not to more 
than allude to the evernieform P. ryssolea, Nyl. (Dufourea, Ach.) or the 
still more anomalous P. lanata, Nyl. (Cornicwlaria, Ach.) so distinct an 
approach in P. Fahlunensis, as respects at least the spermogones, to 
Cetraria, that the predominantly Parmeliine character of the plant, and 
its admitted, close affinity to P, stygia, have proved insufficient, with the 
most learned lichenographer of the day, to retain it in Parmelia. It 
must, however, be admitted that the systematic value of the spermogones 
and spermatia is extremely uncertain; and an illustration of this is. 
afforded by the little cluster of species made up of P. aleurites, P. pla- 
corodia, and P. ambigua. Judged by the spermogones and their con- 
tents, these species, as Nylander has shown, might almost seem in diffi- 
cult proximity to Lecanora § Squamaria; but the real stress of their 
affinities keeps them, without doubt, in Parmelia. 
P. sulphurata, Nees and Flot., occurs fertile in Louisiana (Hale.) —— 
P. aurulenta, Tuckerm. Suppl. 1,1. c. p. 424; Nyl. Syn. p- 382, distin- 
guished, like the last, by its pale-yellow medullary tissue, occurred origi- 
nally on rocks in Virginia, but has been sent to me from most parts of the 
south, and from Illinois (E. Hall.) —— P. Texana, of the same memoir, 
is sorediiferous, and especially comparable with small, smoothish, south- 
ern states of P. Borreri; the lobes, in my numerous specimens, showing 
scarcely any trace of that tendency to elongation so characteristical of 
the American P. tiliacea (P. scortea ‘lobis longiusculis,? Ach. Syn.) 
though the lichen sufficiently agrees with the latter in the spores, and is 
referred to it by Nylander (Syn. p. 383.) ——P. aleurites, Ach., Sommerf., 
Ny, (P. hyperopta, Ach., Imbricaria, Koerb.) is the fertile plant so named 
in Syn, Lich. N. Eng. p. 27, and is common in the higher forest (black 
growth) of the White Mountains, very often in company with P. ambigua. 
