(2) 
characters confessedly point. And it has been found impossible not to 
agree with Nylander, that however remarkable the peculiarities of Per- 
tusaria, this is a type of Lecanorei. I deem it proper to add that the 
whole arrangement of Parmeliaceous Lichens, as now to be set down, 
was completed, before any part of the important papers of Professor 
Schwendener (Uxterszuch. tiber d. Flechtenth. in Naeg. Beitr. 2, 3, 4) con- 
taining, if I mistake not, much suggestive of not dissimilar results, was 
known to me. 
The Usneei, as here taken, are most intimately connected among 
themselves; and so close is their relation to the Parmeliei, that I find it 
impossible to make these two families other than immediately contiguous. 
Umbilicaria, now generally accepted as belonging to the tribe, is also, 
through Omphalodium, brought very close to Parmelia; and may be 
regarded as Fries (L. E£. p. 348) foresaw, the immediate link between 
this and Sticta. It is in Sticta, and the other Peltigerei, that we reach the 
true centre of the tribe; which diverges in Pannaria, and still further, in 
the same direction, in Collemei; and descends finally, in Lecanorei, to 
crustaceous types not easily explicable as Parmeliaceous. 
There is no doubt that the ground-structure of the apothecia of 
Lichens is in every respect comparable with that of sporangia of Dis- 
comycetous and Pyrenomycetous Fungi (De Bary JWorph. and Phys. d. 
Pilze, &., p. 277, &e. Fr. Lich. Eur. p. si. &c.). And it is scarcely 
less certain that in all Lichens—J/yriangium, Berk. and Mont., being 
excluded—this elementary structure, which Schwendener (Flora, 1362-4) 
and Fuisting (Dissert., Berol. 1865) have especially illustrated, is much 
the same. All apothecia exhibit, or are at least included in a variously 
modified proper exciple; and this proper exciple may, in any tribe, be 
further conditioned by an accessory margin of the substance of the thal- 
lus. In the great tribe now immediately before us, embracing so large a 
proportion of the most distinguished types of Lichens, the thallus 
assumes however, manifestly, a peculiar importance; and it is not sur- 
prising that the thalline receptacle, dignified here, for the most part, as 
it is, at the expense of the proper exciple, should become itself char- 
acteristical. 
As respects the spores, the Parmeliacei are remarkable for the pre- 
dominance of the colourless type; and even in the genera referable to the 
other, or normally coloured series, a very large part is also colourless. 
The case is the same with the Lecideacei; and we have thus an evident 
distinction of these especially typical groups of true Lichens from the 
remaining tribes (Graphidacei, Caliciacei, Verrucariacei) looking often 
towards Fungi, in which the coloured type is predominant. 
Reckoning the whole number of species of Lichens as somewhere from 
1350 (Nyl. Syn. 1, p. 75) to 1750, Parmeliacei, as here taken, will include 
not very far from one-half of the whole; and Parmeliacei and Lecideacei 
together, will include not much less than two-thirds. 
