353 
— a compilation from those works only to which I have at 
present access. It could be greatly enlarged by contribu- 
tions from foreign authors, for the labours of the microscopi- 
cal school of lichenologists are daily adding to the number 
of the parasites in question. And I trust in time the list will 
be so enlarged. Meanwhile it is sufficiently full to illustrate 
the following points in the Natural History of Lichens : 
I. The difficulties and absurdities of modern Botanical 
Classification and Nomenclature. 
The majority at least of the genera hereinbefore enume- 
rated may be reduced with propriety to the four following 
type-genera : — 
1. Verrucaria . 
Vcrrucaria. 
Arthopyrenia, 
Thelocarpon. 
Thelidium. 
Mierothelia. 
Endococcus. 
Cercidospora. 
Xenosphaeria, 
Tichothecium. 
Pharcidia. 
Polycoccuin. 
Sorothelia. 
Rhagadostoma. 
Spolverinia. 
Endocarpon. 
2. Lecidea. 
Lecidea. 
Biatorina. 
Buellia. 
Abrotliallus. 
Scutula. 
Karschia. 
Nesolechia. 
3. Calicium. 
Calicium. 
Sphinctrina. 
Stenocybe. 
4. Arthonia. 
Arthonia. 
Opegrapha. 
Pseudographis. 
Placographa. 
Trachylia. 
Acolium. 
Lahmia. 
Leciographa. 1 
Celidium. 
Phacopsis. 
Phymatopsis 
1 Stizenberger apparently arranges it under Buellia (‘ Beit. z. Flccht.,’ 161). 
