It was the intention of Dr Kidston and myself to deal with the main plant-remains of the Old Red Sandstone of this country in preparation for a systematic account of the flora. I cannot continue the work alone without expressing in affection and gratitude how much I owe to my association with him in it. The loss of Dr Kidston's experience, insight, and judgment in dealing with the obscure and peculiar plants of this early period can hardly be estimated. No further results of our joint work had been prepared for publication; but, since we had for some years made common stock of our observations and notes on the subject, Dr Kidston's views on many points are known to me and will be utilised wherever they apply.

The influence of Size as a factor in the stelar morphology of the Filicales (2) and of some Primitive Plants (3) has already been discussed in the Proceedings of this Society. The aim of the present investigation is to determine by actual measurement to what extent Size may have acted as a causal factor in determining the structure and arrangement of the vascular system of Selaginella.

The first five parts of this work on the skeleton, muscles, vascular system, and visceral organs were published in the Transactions of the Society in 1905, 1907, 1909, 1912, and 1913.

The present section deals with a difficult and puzzling system which adds to its fundamental incongruity a range of variation which reduces the normal status to a condition of speculative uncertainty. The works of A. A. Retzius, J. Müller, and Jackson have resulted in a fairly accurate knowledge of the arterial system; but the venous system, which is much more important as regards its morphological bearings, is only imperfectly known, and the series of so-called veno-lymphatic spaces hardly known at all. Unhappily, material for a study of the development of the vascular system of Myxine has still to be obtained. The smallest individual out of many hundreds which I have collected was over 10 cm. long. Beard records a badly damaged 6·5 cm. specimen and Maas one of 8·5 cm. The structure of Beard's example, which I have examined, does not differ in any noteworthy respect from that of the adult, and hence throws no light on embryonic conditions. Consequently the interpretation of the venous system which has been adopted in this paper awaits embryological confirmation, and is to be regarded in the meantime as a working hypothesis only. The spawning grounds of Myxine have not yet been discovered, and it seems likely that the animal spawns in deep water in places remote from its summer resorts.

This piece of work was undertaken as the result of certain observations made during class-work on irregular nutrition. This particular species of Cuscuta was being successfully grown at the time in Glasgow Botanic Gardens, and my sincerest thanks are due to Mr Banks, the Curator of the Gardens, who has very kindly allowed me to have abundant material at all times, and has also provided me with various host-plants upon which to grow the parasite. He has also allowed me to make observations on the plants growing in the Gardens, and to take photographs whenever I wished.

The existing Cycads, with their nine genera and about eighty known species, represent the last lingering survivors of an ancient race that existed in Mesozoic times. There is very little evidence of their geological and geographical distribution throughout that great period; but it seems that up to the close of the Cretaceous they constituted an important feature of the Land Vegetation, with the Bennettitales, Ginkgoales, and Coniferales as their contemporaries. During that long period they were probably represented by many genera and species, and apparently enjoyed a very wide geographical distribution. The nature of their seed as an organ of reproduction seems to have endowed them with great powers of propagation and dissemination, which enabled them to spread over the earth and to occupy dry soils which probably had never before been occupied by Land Plants.

The word “kame” is regarded by one usage as the Scottish equivalent of the Irish term “esker”; according to another usage, the terms are not synonymous, for an esker is regarded as the British representative of the Swedish “osar” and as a ridge of sand and gravel deposited along the course of a river within a glacier, while a kame is a ridge of similar materials deposited outside the glacier along its edge. The Polmont kame, as seen from the railway, strikingly resembles the Swedish osar; but it and those at Carstairs, the best known of Scottish kames, proved, on examination, not to have the cross-banding characteristic of osar, and to be marginal deposits. The typical Irish eskers are also marginal deposits (Gregory, “The Irish Eskers,” Phil. Trans., A, 210, pp. 115–51) and of the same origin as the Polmont and Carstairs kames. A few small Irish eskers have the structure of osar, while many are the remnants of denuded sheets of sand and gravel. I therefore suggested that the term esker, being Irish in origin, should be applied generally, as it is in Ireland, to hills of glacial sand and gravel.

Drumlins are mounds of boulder clay and are characteristic features of the minor topography of Southern Scotland. The word drum or drumlin as the name of these drift hills is indigenous both in Scotland and Ireland. It is common in Scottish place-names as in Drymen, Tyndrum, and Drumadoon. J. Jamieson's Etymological Dictionary of the Scottish Language (1880, vol. ii, p. 116) defines a drum as a knoll or ridge, and refers to its use in the Statistical Account of Scotland as early as 1797. Joseph Wright, English Dialect Dictionary (1900, vol. ii, p. 190), attributes drum to Scotland, but quotes drumlin from Ireland in Antrim and Down. Its first use as a technical term in geology appears to have been in Ireland by Scouler in 1833, who applied it to eskers and to mounds of boulder clay; its restriction to the latter is due first to Maxwell Close (Journ. Roy. Geol. Soc. Ireland, i, 1866, pp. 212, 213.)

At the commencement of the 1924 geological expedition to Iceland, which was conducted by Dr G. W. Tyrrell and the present writer, aided by a grant from the Carnegie Trust, the author took advantage of his earlier arrival in Iceland by devoting his time to a detailed survey of Viðey, a small island which lies 3 miles E.N.E. of Reykjavík. His interest having been aroused by a study of the curious rock specimens which Mackenzie collected from that locality in 1810 (author, 1925), the writer intended at first to make only a rapid examination of the island in order to ascertain their field relations, and, if possible, to determine their mode of formation. A day's field work, however, convinced him that a more protracted survey would be amply repaid, and this was accordingly undertaken; during two days, out of the total of ten which were devoted to this work, the writer enjoyed the invaluable assistance of Dr Tyrrell.

Benbecula signifies “the hill of the fords,” and the island was so designated owing to the fact that there is on it only one hill of any prominence, and that it is connected with the larger islands to the north and south by fords passable only at low water. The origin of the name “Uist” is referred to in a previous communication.

These islands occupy a central position in the Outer Hebrides, lying between South Uist and Harris. They are bounded on the west and north-west by the Atlantic Ocean; on the north-east by the Sound of Harris; on the east by the Little Minch, which at its narrowest part is about 16 miles broad; and on the south by a narrow channel separating Benbecula from South Uist. The area embraced in this communication extends from the Isle of Shillay in the north to the Isle of Wiay at the south-east corner of Benbecula, and includes not only the main islands of North Uist and Benbecula but also a number of smaller isles adjoining the main ones. Including the intervening channels, the total length from Shillay in the north to the southern extremity of Benbecula is about 28 miles.