535 
of Edinburgh, Session 1868 - 69 . 
while determining the species of various British and foreign Lichen- 
collections submitted for that purpose during the same period. 
The types of the parasites referred to are — 
Torula licbenicola. 
Coniotliecium lichenicolum. 
Sphceria ventosaria. 
Microthelia Cookei. 
Stereocaulicola. 
Umbilicarige. 
Nephromii. 
Microthelia rugulosaria. 
Stictaria. 
Parietinaria. 
Basomycearia. 
atricola. 
vesicnlaria 
Detailed observations are included on the variations of Torula 
lichenicola and Coniothecium lichenicolum. 
The group of parasites described (accompanied with two plates 
of seventy figures illustrative of their minute structure) is repre- 
sentative of a large and important section of obscure and little 
understood organisms that are midway in character between Lichens 
and Fungi, and which have been scarcely studied by either Lichen- 
ologists or Fungologists. The observations made upon them by 
the author illustrate several points of great interest in the physio- 
logy, anatomy, morphology, and classification of the lower orders of 
Lichens and Fungi, e.g . — 
1. The extent to which Lichens are affected with parasitic 
growths. 
2. The external resemblance between these parasites — whether 
Lichens, Fungi, or Fungo-Lichens — and the 
Spermogonia, ) 
Pycnidia, > of Lichens or Fungi. 
Apothecia or Perithecia, ) 
3. The connection between parasitic growth and deformities or 
degenerations of the Lichen-thallus or apothecia. 
4. The closeness of the alliance between Lichens and Fungi: the 
impossibility of drawing lines of demarcation. 
5. The fallacies of supposed diagnostic characters or differential 
tests between Lichens and Fungi: especially the iodine-reac- 
tion-test. 
6. The usefulness of establishing a group intermediate between 
Fungi and Lichens — of Fungo-Lichenes. 
4 A 
VOL. VI. 
