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several others, distinctly diverges, exhibiting the characteristical differ- 
entiation of the brown spore; and Gyalecta must be admitted, and is 
admitted, and by authors elsewhere sufficiently disposed to insist on the 
value of such differences, to possess by no means a satisfactory spore- 
character. But Thelotrema, viewed in its whole extent, furnishes an in- 
structive example of a similar confusion of types, on a much larger scale ; 
and the manifest difficulties in the way of dividing this large genus from 
the point of view of the spores, may well influence our construction of 
the smaller assemblage before us. 
The spores of Gyaleeta tend now to an excess of number in the thekes, 
of which G. Valenzueliana, above noticed, G. nana, Tuckerm. Obs. Lich. 
1. ¢. 5, p. 415, and G. corticola (Pachyphiale, Lonnr.) are instances. But 
the last, in the European (Koerb. Parerg. p. 112) as well as the American 
specimens (G. ceratina, Tuckerm. 1. c., fide Nyl. in Bot. Zeit.) reverts 
towards if it does not reach the normal number. 
The thallus is well exhibited in G. Valenzueliana ; but in other cor- 
ticoline species, as G. abstrusa (Wallr.) Arn., G. cornea (Sm.) G. corticola 
(Lénnr.) &c., it finally disappears, and nothing remains but general affin- 
ity to connect the at length biatorine apothecia with the present genus or 
family. With the just-named biatoroid expressions of Gyalecta, I follow 
Nylander in considering G. lutea (Dicks.) and G. pineti (Schrad.) as prop- 
erly associable. 
The denigration of the proper exciple appears an insufficient reason 
for excluding any lichen from the present sub-family which may other- 
wise be referable to it; and instances of the sort are far enough from 
uncommon. Among these we may reckon here the very curious G. rhex- 
oblephara (Lecidea, Nyl. Rhexophiale coronata, Th. Fr. Secoliga sect. 
Sagiolechia, Stizenb.) appearing indeed, at first sight, to have little to do 
with Gyalecta, even in the largest view of the genus. Examined how- 
ever more attentively, the peculiarities of the plant will be found possibly 
more explainable from the point of view of Gyalectine types, than from 
any other; if its position be not in fact determined by that of G. protu- 
berans (Ach.) Anz. (Scher. Helv. n. 203. Herb. Krempelh.) in which the 
exciple is not originally, or truly carbonaceous. Young apothecia of G. 
rhexoblephara are often similar to those of G. exanthematica, except in 
colour. Those of G. protwberans are distantly comparable with G. leu- 
caspis, Krempelh.!; but they rather resemble those of G. lecideoides, 
Massal. (Herb. Th. Fr.) as is remarked also by Koerber (Parerg. p. 109). 
These blackened gyalectine types are especially interesting as illus- 
trations of the near affinity of the present genus to Urceolaria, which 
approaches it in several recedent forms, as particularly in U. actinostoma ; 
while Gyalecta imperfectly anticipates, in like manner, in instances already 
considered, (of which G. lecideoides is one) the Urceolariine spore. And 
it is worth adding that the same radious wrinkling, observable so com- 
monly in the margin of the gyalectine exciple, and deepening into clefts 
