PART IV.—This paper concludes the authors’ account of the Vascular Cryptogams found in the Rhynie deposit. Restorations of the four plants, Rhynia Gwynne-Vaughani, R. major, Hornea Lignieri, and Asteroxylon Mackiei, are given. A few additional features, supplementary to the descriptions of these plants in the preceding papers of the series, are described and illustrated. The hemispherical projections of Rhynia Gwynne-Vaughani are shown to have originated underneath stomata. A comparison is made between them and certain intumescences in existing plants. Areas of necrosis and marked wound-reactions of the tissues around them are described for both species of Rhynia. The apex of a stem of R. major is figured. For Asteroxylon additional figures are given of a large rhizome, of the leaf-arrangement and immature structure of the stem in the region of a shoot-apex, and of the longitudinal markings on the epidermal cells resembling those found in Rhynia Gwynne-Vaughani. The discussion summarises the authors’ views on the main bearings of the facts described in Parts 1–4 on various problems in plant morphology.

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.