(190) 
now to be set down, as to the real value of the distinction derived from 
the number of spores contained in the thekes, the writer cannot hesitate 
to subordinate the differences based upon that distinction by Flotow, and 
to return to the conception, viewed now indeed in the light of more recent 
knowledge, of Fries. And here it is also to be added, that, as those forms 
which recede from the rest in their much larger and fewer spores, are in 
fact forms of the most perfect condition of the species, and might be 
subsumed under that condition with only an extension of its spore- 
character, their place in the arrangement is rather before than after the 
more common, and, as respects the spores only, more normal states. — 
B. petrea (Flot. emend.). (Lecid. atro-alba (Ach.) Fr. L. E. p. 310, max. 
Dp.) a, Montagnei (Lecid. Montagnei & L. geminata, Flot. Koerb. Syst., 
sub Rhizoc. L. geminata, Nyl. Prodr. Rhizocarpon Montagnei, Koerb. 
Parerg. p. 229. Buellia, Tuck. Lich. Calif.). Spores solitary, or in twos, 
in the thekes. Granitic rocks, Greenland (J. Vahle Th. Fr. 1. c.) and 
elsewhere, on the same rocks, in arctic America (Dr. Kane). Massachu- 
setts, on similar rocks, best comparable with Fr. Lich. Suec. n. 406, A, and 
with Anz. Lich. Ital. Sup. nu. 306; as are most of ourspecimens. Vermont, 
on similar rocks, Mr. Frost; the spores commonly solitary. New Jersey 
(Mr. Austin). Rocky Mountains (Prof. Hayden). California, on mica 
slate (Mr. Bolander).——,j, vulgaris (Lecid. petrea, Flot. Koerb. Syst. 
p. 260, sub Rhizoc. L. petrea, Nyl. Prodr.; Lich. Scand. p. 233). Spores 
normally in fours, or in eights. A very common and variable lichen, 
occurring on granitic, and other rocks, especially northward; in Green- 
land (J. Vahl, e Th. Fr. 1. c.) Canada (Mr. Drummond) and New 
England; following the mountains southward to Virginia and North 
Carolina (Rev. Dr. Curtis) and appearing also on the Pacific coast (Mr. 
Bolander). On often inundated rocks in our mountains, the areoles 
disappear in a thin, contiguous thallus (v. lavata, Fr.) or, both areoles 
and apothecia being greatly reduced in size, and the crust oxydated, we 
have, commonly in the mountains and on the north coast of New 
England, the conspicuous v. Oederi, Koerb.——B. geographica (L., 
Scher.) occurring, probably everywhere, on the rocks of arctic America 
(Hook.; Th. Fr.) abounds also in alpine and subalpine districts in Canada 
and New England, and descends far below, in the mountains. It has 
been found southward in the mountains of North Carolina (Mr. Buckley) 
and is common on the sandstones of the coast of California (Mr. Bolander). 
——B. alpicola (Nyl.) Anz., is less distinctly characterized, in such 
European specimens as I have seen (Herb. Torssell. Scher. Helv. n. 173. 
Anz. Lang. 0.199. Rabenh. Eur. n. 618) except by the spores, which 
offer the instructive anomaly of not advancing beyond the bilocular stage. 
In the White Mountains however, the corresponding condition with 
bilocular spores (which is confined to the alpine region) is recognizable 
not merely by the brighter colour of its smaller fronds, contrasting often 
pleasingly with the greener expansions of a, and its larger areoles, but is 
