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XXXIII. — On Old Red Sandstone Plants showing Structure, from the Rhynie 
Chert Bed, Aberdeenshire. Part V. The Thallophyta occurring in the 
Peat-Bed ; the Succession of the Plants throughout a Vertical Section of 
the Bed, and the Conditions of Accumulation and Preservation of the 
Deposit. By R. Kidston, LL.D., D.Sc., F.R.S., and W. H. Lang, D.Sc., 
F.R.S., Barker Professor of Cryptogamic Botany in the University of 
Manchester. (With Ten Plates and One Figure in the Text.) 
(Read May 2, 1921. MS. received June 28, 1921. Tssued separately November 30, 1921.) 
In this concluding part of the series of papers # on the plants preserved in 
the Rhynie chert-band, various remains of lower plants that occur in the peat 
will be described, and some general questions concerning the accumulation and 
preservation of the deposit considered. The paper is divided naturally into the 
parts enumerated below. 
1. An account will be given of a number of forms of Fungi which are met 
with in the decayed remains of the vascular plants, and also in the peaty matrix. 
The fungal remains are so generally distributed that they can be regarded as 
forming an integral part of the peat. In connection with them, the question as 
to whether there is evidence of a mycorrhizal relation between any of the Fungi 
and the Vascular Cryptogams will be considered. 
2. The occurrence of Schizophyta will then be considered and a few well- 
characterised forms, that can be placed in this group, described. 
3. A remarkable algal organism, to which the name Algites ( Palseonitella ) 
Cranii is given, will be described ; scattered remains of this have been found 
at a few spots in the deposit, and we provisionally associate with these some 
interesting but more doubtful remains. 
4. Certain fragments that belong to an organism with the characteristic structure 
of N ematophyton will be described and discussed. These have been met with 
in a limited region of one block of the chert. 
5. The succession of the plants, as determined by the study of a vertical series 
of microscopic preparations, extending from the bottom to the top of a complete 
section collected when the Rhynie deposit was exposed in situ, will be described. 
6. In the light of these facts and of some others obtained from loose blocks of 
the chert, the question of the conditions of accumulation and preservation of the 
Rhynie deposit will be briefly considered. 
More exhaustive study of the deposit will doubtless lead to the recognition of 
further types of Thallophyta, and add to our knowledge of some of those described 
* Part I, Trans. Boy. Soc. Edin., vol. li, p. 761 ; Part II, ibid., vol. lii, p. 603 ; Part III, ibid., vol. lii, p. 643 ; 
Part IV, ibid., vol. lii, p. 831. 
TRANS. ROY. SOC. EDIN., VOL. LII, PART IV (NO. 33). 
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