(174) 
look like outlying representatives of the same type; of which the tropics 
offer us many more modifications. It is difficult not to follow Flotow in 
referring the European Biatora pachycarpa to a variety of H. tuberculo- 
sum; and if the American B. porphyritis is, at present, geographically 
considered, and hence possibly otherwise, more distinct, examples are 
not wanting of forms from the warmer regions of the earth which approach 
it so closely, that we may well doubt whether the remote ancestor of our 
New England lichen differed at all from the predecessor of the tropical 
ones. Nor is it safer here to rely upon the number of spores in the thekes, 
than in Pertusaria ; upon the perplexities in this regard in which genus, 
and especially in the stock represented by P. leioplaca, Koerber (Parerg. 
p. 318) and especially Nylander (in Prodr. Fl. N. Gran. p. 37) furnish 
instructive observations. Thus viewed, the group of lichens now imme- 
diately before us, will be associable possibly in something like the 
following order. 
Heterothecium tuberculosum (Fée) Flot. 
a, porphyrites: apotheciis nigrescentibus, primitus albo-pruinosis, 
margine concolori ; sporis solitariis, 3-6—locularibus. Biatora porphy- 
ritis, Tuck. Syn. N. E., p. 61, & Lich. evs. n. 96.—Trunks in the White 
Mountains; and in swamps in Western Massachusetts. New Bedford, 
Mass. (Mr. Willey). Vermont (Mr. Frost). Distinguishable, as compared 
with the next, by its dark, pruinose apothecia, and shorter spores; and 
remarkable for its northern range. In the finest condition of the lichen, 
which inhabits the original forest, at an elevation of not far from 3000 
feet, in the White Mountains, the apothecia are very large, reaching from 
2 to 3™™, and at length exceeding 4™™., in width. Spores also large, as in 
all the forms; which are scarcely to be well distinguished by differences 
in this regard. 
B, pachycarpum : apotheciis rufo-fuscis (nigrescentibus) margine pal- 
lido dein denigrato ; sporis solitariis, 6-12-locularibus. Lecidea tuber- 
culosa, Fée Ess. p. 107, t. 27, f. 1, & Suppl. p. 103. Biatora pachycarpa, 
Fr. L. E. p. 259. Heterothecium tuberculosum, & v. pachycarpum, Flot. 
in Bot. Zeit. 1.c. Bombyliospora versicolor & B. pachycarpa, Massal. Ric. 
p. 115.——Trunks in tropical countries (Wright Lich. Cub. n. 228. Lin- 
dig. Herb. N. Gran. n. 709, 723, 755, &e.) and occurring also, but rarely 
fertile, in western Europe, and in the Bavarian Alps, (Herb. Borr. Zw. 
exs. 0. 80. Herb. Krempelh. Herb. Th. Fr.) Apothecia commonly 
lighter coloured than those of the last, and the spores longer; but the 
former difference will not hold; and in a Hong Kong specimen, with 
blackened apothecia (Mr. Wright) before me, the spores are quite the 
same with those of the American plant. Nylander remarks (Prodr. 
p. 118) that Fée’s species is scarcely more than an exotic form of Biatora 
pachycarpa; and I am at a loss to indicate any distinction between them. 
