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should belong to Heterothecium, Massal.) that there is possibly no other 
way to distinguish it from H. Domingense (and Bombyliospora) than by 
the mural spore-cells. 
The Buellia-spore is at first colourless and simple; and if we conceive 
this primary condition as becoming (like other modifications) typical, and 
in a lichen otherwise referable to the present, large-spored group, we 
shall have perhaps the best, and in some points of view a far from unin- 
teresting explanation of one of the anomalies of H. sanguinarium. 
The position of myriosporous lichens in the system, must, it is evi- 
dent, be determined, by those lichenists who allow to the anomaly 
referred to only a subordinate value, by whatever other evidence the 
plants afford. Biatorella becomes thus reducible to Biatora ; and Spora- 
statia to Lecidea. And Flotow exercised only a similar act of judgment 
in referring Lecidea conspersa, Fée, to Heterothecium. The very minute 
spores of this species shew indeed no trace of structural modification, 
like that which illuminates those of Rinodina constans ; but the whole 
habit of the lichen associates it, not with Biatora § Biatorella, but with 
the present genus. And the same must be said of the myriosporous 
Lecidea Wrightii (Obs. Lich. 1. ¢. 6, p. 275; Wright Lich. Cub. n. 235) 
which, associable with Biatorella by nothing but the minuteness and 
number of the spores, offers a tartareous thallus ill to be compared with 
anything representing thallus in the group just-named, and apothecia 
with the exact aspect of those of Heterothecium tuberculosum v. porphy- 
itis. 
The genus is, as already remarked, mainly confined to the warmer 
regions of the earth. Of the conspicuous forms known (rather exceeding 
forty) four fifths are intertropical; five of which extend northward into 
our Southern States. Only five are decidedly northern; two of which 
are common to Europe and the northern half of North America, one is 
peculiar to the latter, and two are found only in Europe. 
The designation Megalospora is retained by Massalongo, and by 
Koerber, for H. sanguinarium (L.) Flot., with which species, in several 
respects apparently anomalous,’ the view we have now to offer of the 
genus, as represented here, may not improperly commence. This well- 
known lichen, occurring commonly, on trunks, dead wood, rocks, and on 
the earth-incrusting mosses, in the mountains of New England, where it 
ascends to alpine districts, and also on the north-eastern coast, extends 
probably through arctic America, where Mr. Wright found it in islands of 
Behring’s Straits, and descends the west coast to California (Mr. Bolander). 
Its apothecia are described by several recent writers as structurally im- 
1 Considered as a Lecidea, in the sense of Fries, the plant, or its stock (com- 
pare Nyl. in Prodr. Fl. N. Gran. p. 72) is in fact isolated; whether still kept within 
the larger group, as by Nylander, or made to rank as a separate generical type, as 
by most other recent lichenographers. But this isolation is at least less marked 
from Flotow’s position. 
