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generical separation of the ascendant forms (Anuptychia, Koerb. Syst. 
Tornabenia, Mass.) penetrate really, in Physcia, within the circuit of the 
horizontal ones ;—these last (or the horizontal Physcie agreeing ana- 
tomically with P. ciliaris) being themselves reconcilable, as Nylander has 
shown (Sy2.) with the cluster represented by P. stellaris, through the 
mediation of other states, associable together in every other respect, in 
P. pulverulenta. 
It was not within the proposed scope of the skilful vegetable anato- 
mist first cited to compare generally the apothecia of Physcia and Par- 
melia, but Fries had already done this: and it was only left to De Nota- 
ris (Framm. Lich. 1844) to show the uncertainty of the supposed dis- 
tinction between the presence or absence of gonidia in the portion of 
thallus immediately under the hypothecium ;! and fully to describe the 
spores. By this description the spore-character of the genus was shown 
to possess a remarkable precision and uniformity, and no exceptional 
facts offered, to disturb the estimate. That another estimate was how- 
ever possible, might well have been inferred from the spore-phenomena 
of other groups; and such amended valuation has now become necessary. 
If then we look at the bilocular modification exhibited by the spores of 
most Physcie as only one of a series of changes accomplished, in the 
process of its differentiation, by the brown spore, the value of this modi- 
fication, in the system, is at once qualified; and there will be no pre- 
sumption, but the contrary, against the possible occurrence of any or all 
the other gradal differences of the same spore-type, within the circuit of 
the same natural genus. And Nylander has described, within the small 
cluster represented by P. obscura, quadrilocular spores (P. obscurascens, 
Nyl. Syn. 1, p. 429) and 6-8-locular, verging on sub-muriform (P. plin- 
thiza, Nyl. Lich. N. Zeal. in Linn. Soc. Lond. Journ. 9, p. 249).? 
About two-thirds of the more conspicuous forms of the genus are known 
to occur within our territory. As compared with Parmelia, in which 
species extending northward are largely predominant, Physcia has a 
1 See the cited memoir under Hagenia obscura and H. stellaris (p. 11) and 
also under Ricasolia (p. 5) and Ramalina (p. 33). The variableness of the point 
in question might also be illustrated from Parmelia, and Usnea; but the charac- 
ter has kept its place in the books, with few exceptions. On a full review of the 
forms of Lecanora subfusca, Stizenberger (Bot. Zeit. 1868, nu. 52) has found it im- 
possible, —in which conciftsion, the present writer, having repeated his analysis 
with some care, cannot but accord —to allow this feature even specifical weight; 
L. Parisiensis, Nyl. (Lich. Jard. Luxemb. in Bull. Soc. Bot. Fr.) proving to be 
quite inseparable from the older species. 
2 The modification of spore-structure exhibited in P. obscurascens is foreshad 
owed indeed in the spore-history of the ascendant conditions of P. speciosa (Tuck. 
in Wright Lich. Cub. n. 82, 83) as Nylander (Syn. p. 415) has fully indicated; but 
it is easy to see that the spores of this noble species, taken in its full extent, are 
typically bilocular. 
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