W. H. Lang. 1926. Contributions to the Study of the Old Red Sandstone Flora of Scotland. III. On Hostimella (Ptilophyton) thomsoni, and its inclusion in a new genus, Milleria. IV. On a specimen of Protolepidodendron from the Middle Old Red Sandstone of Caithness. V. On the identification of the large "stems" in the Carmyllie Beds of the Lower Old Red Sandstone as Nematophyton. Transactions of the Royal Society of Edinburgh 54(21):785-799 [P. Gensel/C. Bernard/C. Bernard]