8 
genus.* The consideration of the numerous, sometimes 
sufficiently significant instances, in which nature ap- 
pears to point in the direction we have taken, must be 
left for another place. Let me however be permitted 
at least to say, that if no lchenist would venture to 
separate generically the two forms of Arthonia cyrtodes, 
ofthe present writer, (Wright Zich. Cub. n. 245,246) 
the way then is plainly open for the whole of the argu- 
ME a ee of Biatora, Naeg. & Hepp 
(Hepp Abdild. Sp. t..1) is in entire accordance with the 
view here taken of the spore-characters as well of 
Biatora and Lecidea as of Lecanora; but I am unac- 
quainted with any writer who has touched the instan- 
ces alluded to in a really appreciative way beside Dr. 
Th. Fries (Lich. Arct. p. 187, 185, 226,) though except 
in a very few, isolated examples, as Gyalecta and Rhi- 
zocarpon (Gen. p. 91) the reasoning suggested by his 
observations has not as yet appeared to modify his con- 
structions. 
According to these views Parmelia proper, Ach., will 
fall into . Theloschistes,** Parmelia, and Physcia ; and 
Lecanora into Placodiwm (DC.) Naeg. & Hepp, Lecan- 
ora, and inodina. Excluding the biatorine forms of 
Placodium fromthe JLecdeei, the latter will have no 
examples of the polar-bilocular sub-type ; but Hetero- 
thecvum, correspondin gto Physcia and Rinodina, will 
(*)“Respondent plene” (Patellaria, Fr.) {Lecideis Lichenum, 
in quibus, ut Calictis et omnibus naturalissimis generibus, spo- 
ridia simplicia et eximie septata variant.” Fr. Summ. Veg. 
Scand. p. 366, not. 
(**) Equivalent here to Xanthoria (Th. Fr.) Stizenb., and only 
preferred to the latter on account ofits priority : the section of 
Parmelia called, at one time, Xanthoria by Fries (8. O. V. p. 
246) having never been taken by him in any higher sense, 
