SHOWING STRUCTURE, FROM THE RHYNIE CHERT BED, ABERDEENSHIRE. 659 
the branch-trace ( hr . tr.) is cut in the neighbourhood of the parent stele, while the 
most distal part of the branch is shown divided into two ( Ba and Bb ) adjacent 
to the main stem, but not connected with it. 
Possible Fertile Region of Asteroxylon. 
The parts so far described are shown by evidence of continuity, by the existence 
of intermediate grades, and by histological agreement to be the rhizomes, stems, and 
leaves of one plant. We have thus a fairly complete knowledge of the vegetative 
organs of Asteroxylon MacJciei. 
We owe our knowledge of the structures that have now to be described entirely 
to two small blocks of chert, which were found loose. In sections of one of these a 
number of small axes of peculiar type, with single or paired steles (fig. 107), had been 
met with, associated with stems, leaves, and rhizomes of Asteroxylon, when Dr Gordon 
kindly sent us a section he had cut from another loose block of the Rhynie. chert. 
He also sent us the block, which was cut into a series of sections. 
We wish to express our indebtedness to Dr Gordon for this important addition 
to the material upon which this paper is based. 
This block proved to be a bedded peat, free from sand, and largely made up of 
portions of the peculiar type of axis mentioned above. In the peat were a number 
of sporangia of a new type, and numerous scattered spores derived from them. 
The peculiar axes and the sporangia were associated with stems of Asteroxylon of 
various sizes, one large one showing the endogenous branching already described. 
There were also structures resembling the rhizomes of Asteroxylon. Some of these, 
unlike the other remains, tended to cross the bedding as if they had penetrated an 
already formed peat. 
The appearance of the peat in the block we received from Dr Gordon, and 
especially the association with undoubted Asteroxylon of the peculiar axes that 
have to be described, will be gathered from the photographs on PI. XV, figs. 102-106. 
The region in fig. 102 shows a large stem of Asteroxylon and some more or less 
well-preserved smaller stems. The peat in the lower portion of the figure is made 
up of the peculiar axes, and the track of a perished rhizome of Asteroxylon is traceable 
obliquely across the bedding. Fig. 104 shows a fairly large stem of Asteroxylon 
below, while the peat above is made up of a mixture of the peculiar axes and 
of rhizome-like branches of Asteroxylon, or of isolated strands of xylem composed of 
the characteristic tracheides of this plant. In fig. 103 the branching structure has all 
the features of a root-like rhizome of Asteroxylon. It is associated with character- 
istically preserved specimens of the peculiar axes, only the epidermis and the central 
cylinder of which have not perished. Another rhizome-like axis of Asteroxylon is 
shown in transverse section in fig. 106, close to one of the peculiar axes, which is 
exceptional in having the cortex preserved. Isolated strands of xylem are present in 
TRANS. ROY. SOC. EDIN., VOL. Lll, PART ill (NO. 26). 102 
