856 DR R. KIDSTON AND PROF. W. H. LANG ON OLD RED SANDSTONE PLANTS 
below. It is probable, however, that the forms which have been met with in the 
examination of the numerous sections prepared for the study of the vascular plants 
and the composition of the deposit afford a not inadequate idea of the remains of 
lower plants preserved in the Rhynie peat-bed. Their description will fittingly 
complete the account of our investigation of the Botany of the deposit. 
1. The Fungi of the Rhynie Deposit. 
The most abundant remains of lower plants in the Rhynie deposit are clearly 
Fungi, of which a considerable number of forms can be distinguished. Along 
with Bacteria, which will be considered in the next section, they formed an integral 
constituent of the peaty mass, as they do of recent peats. 
Although the fungi are often as perfectly preserved as were the vascular plants, 
they do not afford characters that are reliable as evidence of their classificatory 
position. All the fungal remains to be described below consist of stout or fine 
hyphse of the vegetative mycelium and various types of vesicles and resting-spores 
(chlamydospores) borne on this. The mycelium is usually non-septate, although 
one example of a clearly septate condition will be described. 
Even when they appear to retain recognisable forms that recur in the deposit, 
it is hardly possible to be sure of the specific distinctness of the various types of 
mycelium with resting-spores found in the more or less decayed plant-remains and 
the peaty matrix. No student of existing fungi would, we believe, feel justified 
in distinguishing fungi found in a mixed growth in decayed organic matter when 
he had only vegetative mycelium and chlamydospores to deal with. Distinctive 
reproductive organs or constancy under culture would be required, even in the 
case of Imperfect Fungi, and the investigator would be prepared for the same 
species assuming a variety of forms as regards diameter of hyphse and size of 
resting-spores. 
It is necessary, however, to bring as much order as possible into the description 
of the various fungi met with so abundantly in the fossil condition in the Rhynie 
peat. The plan adopted will be to describe and illustrate the main form-types 
depending on appearance, relative size, and also in part on the place of occurrence. 
The possibility of distinguishing specific forms will then be considered, and some 
well-chaTacterised forms will be named and diagnoses given for them. 
We have deliberately ignored doubtful remains, and in all cases sought for 
evidence of definite organisation, such as the attachment of vesicles or spores to 
hyphse, or the structure of the spore-wall. 
The fungi occur mainly in the portions of the vascular plants, but to some 
extent in the matrix. In most cases they had evidently lived as saprophytes. 
The question as to whether any of them may have been mycorrhizal during the 
life of the vascular plants will require consideration in the general discussion which 
will follow the particular descriptions. 
