SHOWING STRUCTURE, FROM THE RHYNIE CHERT BED, ABERDEENSHIRE. 887 
of comparison with this group. The wide non-septate tubes of Nematophyton 
have long been recognised as being more readily comparable with the tissues of 
such Algse as the Udotese than with the septate cell-rows of the tissue derived 
by cell-division that make up the thallus of the Lgminariaceie ,* although the size 
attained by the fossil plant suggested comparisons with the latter. 
While the general structure makes it somewhat difficult to think of Nematophyton 
as a land-plant, this possibility gains prominence in the light of the occurrence 
of the plant in the Rhynie deposit. Dawson’s view of Nematophyton Logani in 
the Lower Devonian rocks of Gasp6 was that its large trunks had grown rooted 
in soils which were covered with a growth of Psilophyton and Arthrostigma, 
and that, while probably a marsh-plaut, it was not marine. f The presence of 
Nematophyton in the terrestrial Rhynie deposit supports the conclusion drawn 
from the mode of occurrence of N Logani at Gasp6. Such a terrestrial mode 
of life of the plant would not be inconsistent with fragmentary remains being 
preserved in what are more probably marine deposits, while it is difficult to 
account for the repeated occurrence of a marine plant in terrestrial deposits. 
The facts so far known, although they involve difficulties, would thus appear to 
be in favour of Nematophyton , whatever its systematic position may prove to 
be, having been a marsh- or land-plant of Silurian and Devonian times. 
Nematophyton Taiti, n.sp., Kidston and Lang. 
Small fragment showing a construction of wide and narrow tubes characteristic 
of the genus. Tubes of wider system showing a range in size from 20 n or less 
up to 52 n ; mostly about 40 n. Thickness of wall varying from 2 n to 14 n or 
more, probably in relation to condition of preservation. Some narrow tubes of this 
* It may be noted that a recent suggestion, while emphatically dismissing comparison with the Laminar icex, 
treats Nematophyton in connection with massive Fungi (Church, Thalassiophyta, p. 49 and footnote). 
t Dawson’s views on this -point are expressed in a number of his publications (e.g., The Fossil Plants of the 
Devonian and Upper Silurian Formations of Canada, 1871, and The Geological History of Plants, 1888), but most 
clearly and recently in Penhallow and Dawson, Trans. Canad. Roy. Soc., vol. vi, 1888, pp. 27-36. It will be 
remembered that these views were founded on study of the mode of occurrence of the plant as shown in the rock- 
sections exposed at Gaspe and the Bay des Ohaleurs. Their nature may fairly be given by some extracts from the 
last-named paper, though the context should be consulted. “ The mode of occurrence and state of preservation 
of the specimens seemed to make it certain that they had belonged to land-plants ” (p. 27). “ I also found stumps 
with branching roots apparently rooted in situ in the shales and argillaceous sandstones of the locality ” (p. 28). 
“ I also ascertained that these remarkable plants had probably grown in the clays and sands in which Psilophyton 
and other plants had been rooted, and consequently, that though probably marsh-plants they were not marine. 
They must have grown on low flats, probably often inundated, though whether this was with salt or fresh water 
is indicated merely by the negative fact that no properly marine organisms occur in the containing beds ” (p. 28). 
“It was further found that Psilophyton princeps, P. robustins, Arthrostigma gracile, and Cordaites angustifolia were 
constant associates of these plants” (p. 29). In connection with the last quotation, it is to be noted that the 
remains referred to as Cordaites angustifolia were regarded by Dawson as of quite uncertain nature, and are even 
discussed as possible foliage of Nematophyton ( loc . cit., p. 34). Fig. 3 in the paper from which the above extracts 
have been made shows a trunk of Nematophyton Logani resting on an underclay filled with Psilophyton. Fig. 4 
shows another trunk embedded in a bed of shale containing Psilophyton, the bed being underlain and overlain 
by sandstone. 
TRANS. ROY. SOC. EDIN., VOL. LII, PART 1Y (NO. 33). 136 
