SHOWING STRUCTURE, FROM THE RHYNIE CHERT BED, ABERDEENSHIRE. 859 
those of the fungus described above under Fungus No. 2. These resting-spores, 
specimens of which are represented in figs. 12 and 13, were about twice the size of 
those of the preceding fungus, their diameter being about 500 m, though the 
specimens in this case also exhibit considerable differences in size. The thick 
hyphal stalk bearing the resting-spore is all that has been seen of the mycelium 
of this type. Although when typically developed this is a very distinct form, 
it must be kept in connection with Fungus No. 2, since specimens of resting-spores 
intermediate in size have been met with (of. fig. 12 on the right). These large 
resting-spores do not show the distinct double wall that is so often, though not 
always, met with in the preceding form. The thick wall (fig. 14) is here best 
described as distinctly stratified. There is first an outer layer, the surface of which 
is brown ; then a wide, intermediate, more or less clear layer ; and lastly, an inner 
brown layer. The intermediate layer is sometimes laminated or stratified (fig. 13). 
These layers remain connected, but the contents, limited by a thin or thick brown 
membrane, often contract more or less from the wall. 
Fungus No. 4. (Figs. 15 and 16.) 
The fungus represented in figs. 15 and 16 is placed here, since its resting-spores, 
like those of the two preceding forms, have thick walls showing a differentiation into 
layers. It occurred in a decaying portion of a stem of Asteroxylon. A moderately 
fine mycelium was present in the tissue, and in relation to it were the thick-walled 
oval or spherical resting-spores shown in the figures. These are evidently mature, 
and, though exhibiting a rather wide range in size, the diameter of most of them 
is in the neighbourhood of 120 u to 150 u. This is considerably smaller than the 
spores of Fungus No. 2, from which these resting-spores also differ in the absence 
of any indications of separation of the layers of the wall. A few of the resting- 
spores in the group (which are not shown in the figure) are distinctly larger, and 
thus narrow the interval between this form and Fungus No. 2 ; on the other hand, 
some are distinctly smaller than the majority, and approach in this respect the 
resting-spores to be described next. 
Fungus No. 5. (Figs. 17 and 18.) 
This form is only placed here on account of the relatively thick wall of the 
small oval resting-spores, the major diameter of which was about 60 m. It does 
not call for more detailed description in addition to its representation in figs. 
17 and 18. 
Fungus No. 6. (Fig. 19.) 
We may place here as naturally as anywhere the rather ill-defined form of 
fungus shown in fig. 19. This occurred in a decaying stem of Rhynia major, and 
had the branched, non-septate mycelium, swelling into moderately small vesicles, 
well preserved. Since adjoining stems of Rhynia major showed oval thick- walled 
