SHOWING STRUCTURE, FROM THE RHYNIE CHERT BED, ABERDEENSHIRE. 891 
sporangia. The stems in Bed 1 14, though somewhat (decayed, are hardly compressed 
and lie loosely in the peaty matrix which separates them. The smaller stems have 
a stellate outline, due to unequal contraction with ridging of the surface ; they were 
evidently less firm and rigid in life than the larger stems. The section of Bed K 
shows that the lower portion consists mainly of peaty and sandy matrix, above which 
comes a narrow layer of peat with uncompressed stems that are almost amorphous. 
In the lower (L 16) and upper (LIT) portions of the following Bed L, which still 
contains Rliynia major only, the preservation of the tissues is of the usual type. 
Very well-preserved stems, which may even show the contracted protoplasmic 
utricles of the cells, occur alongside others that are more or less decayed or broken 
down. In Bed M a change in the composition of the peat is met with. Stems of 
Rhynia major are found as in the preceding beds ; mixed with these in M 186 and 
throughout the upper portion (M 18a) forming a pure peat, there are remains of 
Hornea -stems, rhizomes, and sporangia being present. Hornea having thus 
reappeared in this section of the chert-band, persists in the two levels of the last 
peat-bed N. In N 19 the prominent remains are large and very perfectly preserved 
stems of Rhynia major , but stems and sporangia of Hornea are associated with 
them. In N 20, the uppermost bed of the chert-band showing a peat formed of 
plant-remains, this is composed entirely of the parts of Hornea with their usual 
rather imperfect preservation. The last bed of the section, marked 0, which 
consisted of siliceous sandstone with carbonaceous remains, was not examined in 
detail. 
Having thus traced the vertical distribution of the vascular plants through this 
section of the deposit, the general distribution of the Thallophyta remains to be 
indicated. This need not be treated in detail, for there is evidence that some 
forms of fungi are present in the lowest and highest beds. Their nature and 
abundance in the various beds show a general relation to the remains of vascular 
plants composing the peat and their mode of preservation. Practically all the 
Thallophyta that have been described occurred in Bed A"l at the base of. the 
deposit ; it has been shown above that all the vascular plants were present in 
this region also. Some of the fungi have only been found in this lower region 
(e.g. Palseomyces Asteroxyli, P. Horneae). Others, such as P. agglomerata and 
the intrusive fungus described as Fungus No. 14, occurred here and are met with 
again in the Hornea peat of the uppermost beds. The most widely distributed 
fungus was Paldeomyces Gordoni, often with intrusive forms of the types described 
under Fungus No. 15. 
Of other Thallophyta, unicellular Bacteria were probably widespread, but, for 
reasons that have been given, are difficult to identify. The filamentous form described 
as Schizophyta No. 2 ( Archaeothrix contexta) was typically present as a felt above 
the Rhynia Gwynne-Vaughani peat at certain places in Bed A"l. It also occurred 
around decaying fragments of R. Gwynne-Vaughani , and is met with again in Bed 
