The glaciation of the South Orkneys is very similar in its general character to that of Graham Land, and it will be convenient, before going on to the detailed description, to give a short summary of already published accounts of the glaciers of that region.

Our knowledge of the Antarctic fish-fauna has greatly increased during the last ten years. The Belgian expedition to Graham Land (1897–1899) was followed by that of the Southern Cross to Victoria Land (1898–1900), fitted out by Sir George Newnes. Next were the British expedition of the Discovery to Victoria Land and Edward Land (1901–1904), the German voyage of the Gauss to Kerguelen and Willhelm Land (1901–1903), and Nordenskjöld's Swedish expedition to South Georgia, the South Shetlands, and Graham Land. Then came the voyage of the Scotia to the South Orkneys and Coats Land (1902–1904), and Charcot's expeditions to the Palmer Archipelago and Graham Land in the Français. (1904–1905) and the Pourquoi Pas? (1908–1910), and finally Shackleton's expedition (1908–1909).

The genus Cephalodiscus was instituted by M'Intosh for a species, C. dodecalophus, which had been obtained by the Challenger Expedition. After the publication of the full account of this species, by M'Intosh and Harmer (87) in the Challenger Report, succeeding papers for nearly twenty years were all based on the original Challenger material. The subject was in particular re-investigated by Masterman in a series of papers (971, 972, 98, 99, 03). The Siboga report, published by Hakmer (05) in 1905, added three Oriental species to the genus. Schepotieff (05, 07, 08) devoted several papers to a further description of the Challenger material; while, more recently (09), he has described an interesting new species, C. indicus, from Ceylon. In 1906 Ridewood (06) described C. gilchristi from South Africa; and in the following year he gave an account (071) of the two species which had been dredged by the Discovery Expedition; and (072) of the development of the plumes in four species of Cephalodiscus. One of the Discovery species, C. nigrescens, had been described two years earlier by Lankester (05), in a preliminary paper; and Ridewood (12) has recently brought forward evidence to show that this species had been dredged by the Erebus and Terror Expedition in 1841 or 1842. In 1907 Andersson (07) added no less than six species to the genus, in describing the results of the Swedish South Polar Expedition, though we give some evidence (pp. 559–563) to show that one of them, C. inæquatus, is synonymous with C. hodgsoni, which had been described by Ridewood (071) earlier in the same year, from the Discovery collection. The most recent addition to the list of species has been given by Gravier (12), who has published an account of C. anderssoni, a new species which was obtained by the second French Antarctic Expedition.

During the voyage of the Scotia in the Weddell Sea, and during her wintering at Scotia Bay, South Orkneys, I measured as many of the seals taken as possible. I was usually assisted in this work by Mr WILTON. When a seal was killed near the ship, and it could be arranged, I also weighed them both in whole and in part, weighing the different viscera as at a human post-mortem examination. The results of these investigations are now summarised in tabular form, which makes it easy at a glance to make comparisons. In addition to the measurements and weights of the true seals of the Antarctic regions, those of a fine specimen of Otaria jubata (the Patagonian Sea-lion) secured at the Falkland Islands are also given.

The present report deals with the whole of the Schizopoda and Stomatopoda in the Scotia collections, and with those Isopoda which were taken in localities outside the limits of Antarctica. I am indebted to the courtesy of Dr W. S. Bruce for the opportunity of examining and reporting on these collections. The report on the Antarctic Isopoda is being prepared by Mr T. V. Hodgson.

I also include a few notes on a small collection of Schizopoda which were taken by the Discovery on its outward journey to the South Pole, for the opportunity of examining which I am indebted to the kindness of Dr W. T. Calman, of the British Museum. These latter records are most appropriately included here along with those of the species which the Scotia captured on her outward journey, over very nearly the same ground.

The Principles of Archimedes*—It is well known that the mechanics of floating bodies, and the laws which govern their equilibrium, were established and enunciated by Archimedes, the Sicilian, in the third century before our era. The following propositions, demonstrated in the first book of his treatise on this subject, embody the fundamental principles of the hydrometer :—

(a) The surface of any fluid at rest is the surface of a sphere whose centre is the same as that of the earth.

(b) Of solids, those which, size for size, are of equal weight with a fluid will, if let down into the fluid, be immersed so that they do not project above the surface, but do not sink lower.

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

The present section does not include the teeth, which, belonging properly to the skin, will be described when the skin and its appendages are dealt with. It will be noticed from time to time that I have to record striking differences from results obtained by other authors. Such differences must, of course, be recorded; but in recording them it must not be understood, unless the contrary is expressly stated, that the observations under discussion are necessarily inaccurate. One cannot investigate Myxinoid anatomy without frequently coming up against somewhat astonishing variations, and I have long been convinced that there must be races or colonies of Myxine which have not been distinguished specifically, but which, nevertheless, possess anatomical features in common. To give one instance out of many. Mr R. H. Burne has described in detail an anal slime gland in Myxine.

The main purpose of the following investigation is to improve the existing Approximate Theory of Beams by bringing it into closer relationship than has hitherto been done with exact solutions of the fundamental differential equations of equilibrium. In its aim, method, and results the paper closely resembles one already published in these Transactions on the corresponding Theory for Plates (vol. xli., 1904). It is less comprehensive than the latter paper, as it deals only with a beam of circular section; but the analysis is of such a nature that the chief results can be extended almost immediately to a beam of any form of section, on the assumption merely of certain Existence Theorems.

The instrument being closed, its true weight is constant.

Let it be assumed that our experiments are actually made in vacuo, at the sea-level in lat. 45°. In these conditions the standard gram exerts a vertical pressure of 1 gram (true).

We weigh the hydrometer and find its weight to be W grams. We now float it in distilled water contained in a suitable cylinder. In the construction of the hydrometer the internal load has been so adjusted that, when immersed in distilled water of the standard temperature T, which is to remain unaltered during the whole of the experiments, the surface of the water shall cut the stem in some line C, near its junction with the body of the instrument. Then the weight of the water displaced by the hydrometer is exactly W grams.

Au retour de sa belle campagne de 1902 à 1904 dans l'Antarctique, M. le Dr. WILLIAM S. BRUCE m'a fait l'honneur de m'offrir l'étude des Spongiaires recueillis à bord de la Scotia. Voici de quoi se compose cette collection qui, à certains égards, offre un intérêt considérable.

Although the osteology of Antarctic seals has been very completely discussed, notably by the late Dr J. E. Gray, Sir William Turner, and Professor Robert Thomson, yet the literature regarding the subject is somewhat scattered. I have therefore considered that it might be important from the point of view, as it were, of an index to publish a complete series of photographs of a set of the skulls of seals taken by the naturalists of the Scotia during the Antarctic voyage of 1902–1904.

When determining the specific gravity of a saline solution by the hydrometric method, it is necessary first to find the weight which must be added to the hydrometer to immerse it to the 50-mm. mark when floating in the saline solution at the chosen standard temperature. This added weight is found by a series of observations in exactly the same manner as with the hydrometer in distilled water (see § 14 et seq.).

The details of three series of observations with hydrometer No. 17 in a solution of ⅛ gram-molecule of cæsium chloride in 1000 grams of water at 19·50° are given as an example in Table C. This table is arranged in the same manner as Table A1.

The material brought home by the Scotia and available for examination consists in all of fifty-five samples of deposits from the floor of the ocean. The majority of these consist of true “deep-sea” deposits, i.e. material from depths of over 100 fathoms; but, for convenience, the description of a few samples from shallow waters (mostly in the neighbourhood of the S. Orkneys) is also included in this report.

The number of deposits is considerably less than the number of soundings taken by the Expedition, because, for various reasons, a sample of deposit was not obtained in every case where a sounding was taken.

For the opportunity of examining these specimens I am indebted to Dr W. S. Bruce, the leader of the Scottish National Antarctic Expedition, 1902–1904. I should like to take this opportunity of expressing my thanks to him, and also to Dr Marett Tims for his assistance during the preparation of the paper.

A considerable number of Chætognatha were collected on the Scottish National Antarctic Expedition of 1902-1904. Some two or three hundred tow-nettings were examined, and about ninety yielded some of these forms. Beside the tow-netting samples there were twelve tubes of these animals taken in the vertical net or the trawl.

A laboratory is an inhabited room, and in Northern Europe the temperature of such apartments lies generally between 12° and 20°C. Consequently we find that a large amount of specific gravity work has been done at 15°C. by Gerlach, at 19·5° C. by Kremers, and at 17·5° C. by others ; while the calorimetric work by Julius Thomsen, extending over the last half-century, was all done at the temperature 18° C.

The fauna of the Polar regions is of deep interest to zoologists generally, that of the Antarctic specially so, and in this the Rhizopodist can justly claim his share.

Since the return of the Challenger Expedition in 1876, the later British expeditions to this area, with the exception of the Scottish National Antarctic Expedition, did but little in the way of sounding and trawling in the deeper waters of the Antarctic. Although much additional work has been carried out, and many new and rare species of the higher forms of marine life from this region have been brought to light, comparatively little has been added to the Rhizopod fauna since the results of the Challenger Expedition were published. The following pages on the Foraminifera are due to the energy and enthusiasm of Dr W. S. Bruce, F.R.S.E., and his colleagues. The genera and species here enumerated and described have been obtained from samples of deposits sent to me at intervals by Dr Bruce and Dr J. H. Harvey Pirie, collected by them, during the S.Y. Scotia Expedition in 1903-4, chiefly from the area of the Weddell Sea, where the ocean floor is covered with terrigenous deposits of Blue Mud, or (as Dr Pirie calls them) Glacial Muds and Clays.

The collection of Scotia corals is naturally small, since the main work of the Scottish National Antarctic Expedition was in high Southern latitudes, but, during the outward and homeward journeys of the Scotia, collections were made, when opportunity presented itself.

The species are interesting distributionally, but their soft parts are largely decayed. There are five species, of which one is a known species; three dead masses, generically determinable; and the last, a new species, which may in future prove of even greater interest than at the present time.

The Scottish specimens described in this memoir are all the property of Mrs Robert Gray, and I am exceedingly indebted to her, not only for entrusting them to me for description, but for allowing them to remain in my hands for a lengthy period. None of the collections of the Geological Survey, nor those of Glasgow University, contain any cystids from Girvan. Besides her Cystidea, Mrs Gray has submitted to me her Crinoidea and several interesting specimens of Edrioasteroidea.