vestigated, of finding characteristic forms, which would enable us to place them with certainty as the equivalents of the Lower Silurian rocks, so well defined by Sir Roderick Murchison as occurring in Ross and Sutherlandshire. 2nd. The deposits on the eastern side of the island, and skirting the shore of the Sound of Islay from Ard-na-huamh on the north to Balleochreoch on the south, are of Cambrian age. Although the author has not seen the precise equivalents of the greenish-grey micaceous flags, with the felspathic partings found on the north side of Big-Free-Port Bay, on which we find sun-cracks, rain-prints, and what some suppose to be annelid tracks or burrows, yet they coincide so well with similar rocks, so very clearly shown by Sir Roderick Murchison as occurring in Sutherlandshire, where their relation to the inferior conglomerates is so ably traced, and also those described by the late Mr. Salter from the Longmynd beds in Wales, that if similarity of fossil forms are to govern us in determining the relation of formations, then those stratified rocks exhibited on the shore at Big-Free-Port and to Balleochreoch, folding over and surrounding the basic conglomerate mass, can only be placed in a similar stratigraphical position to those referred to by the above able authors, thus extending our knowledge of Cambrian rocks occurring further south in Scotland than has been hitherto recorded. The author quite agreed with Prof. Ramsay in supposing that these rocks were deposited in an inland and freshwater lake; and that those cracks are due to the influence of the sun is abundantly evident. If they had been deposited in an estuary of the sea, the soft mud would not have got time to crack, as each inflowing tide would have kept the matrix sufficiently moist to prevent its shrinking. 3rd. The metamorphic rocks on the western extremity of the island, and skirting the shores of Lochendale for nine miles to the east, and dipping S.S.W. or nearly at right angles to the plains of stratification of the preceding deposits, are of Laurentian age. They differ so widely both in mineral character and stratigraphical aspect from those of the central valley and eastern side of the island, that there can be little doubt regarding their proper identification. Their lithological aspect and mineral character coincides so well with the fundamental Gneiss of Sutherlandshire, and designated by Sir Roderick Murchison as of Laurentian age, that we have not the slightest hesitation in identifying those of Islay as belonging to the same period. 4th. In the basic conglomerates on the eastern side of the island we have got traces of striated rocks imbedded in the mass, although we are not prepared to speak with any degree of certainty regarding the source or direction of the materials constituting the conglomerate mass. If, however, we glance at the topographical aspect of the Highlands and Island, and compare the imbedded boulders of granite with the granites found in situ throughout the Highlands, we feel the necessity of tracing them to another source, and hope we do not overstep the bounds of prudent speculation in suggesting that those erratics are the reassorted materials of some great northern continent that has yielded to the ceaseless gnawing tooth of time, leaving those scattered fragments as the wreckage of its former greatness, and that the materials of which the mass is composed have in time, deeper than we have hitherto suspected, been transported by the agency of ice. If so, then this is another proof that we are not in a position to limit the agency of ice to any single period of our earth's history. Additions to the Fossil Vertebrate Fauna of Burdiehouse, near Edinburgh. By Prof. TRAQUAIR. On the Structure of the Dictyoxylons of the Coal-measures. Professor W. C. Williamson referred to Mr. Binney's original description, in 1866, of Dadoxylon Oldhamium, and to his own subsequent paper, in which he separated his new genus Dictyoxylon from the Dadoxylons. He then described the former genus in detail, commencing with D. Oldhamium. In this plant there was a central medullary axis of cellular tissue with several detached longitudinal bundles of vascular tissue at its circumference. Outside this is a lax ligneous zone, to the interior of which the bundles just referred to are adherent. The vessels of the ligneous zone are reticulated, and arranged in radiating series, the radiating laminæ being separated at very frequent intervals by thick cellular medullary rays, consisting of numerous vertical series of cells. External to the woody zone is a very thick and characteristic bark, the inner portion of which is loosely cellular, but the exterior has a different structure. It consists of a combination of cellular parenchyma and dense elongated prosenchyma, the latter appearing in the transverse section as a series of dark bands, radiating at varying angles from the inner to the epidermal layer of the outer bark. Vertically these prosenchymatous bands are prolonged as layers, which extend upwards and downwards in a wavy manner, alternately approaching and receding from one another, so that a tangential section exhibits a series of lenticular areola whose longer axes correspond with that of the stem. The outermost bark-layer appears to be a cellular epidermal tissue, which has probably supported external appendages, either scales or leaves. In the inner layer of the bark we see a series of variously developed vascular bundles which spring as branches from the ligneous zone, but which ascend for a considerable distance without escaping through the bark, whilst a second series of branches are given off in like manner, but which at once perforate the bark in their passage outwards. This plant is from the lower coal-measures of Lancashire and Yorkshire. A second form of Dictyoxylon, to which the author gives the name of D. radicans, has evidently been a branching root which has been traced continuously into its ultimate rootlets. This plant has no pith, and its compact woody zone, consisting of reticulated vessels, is furnished with medullary rays of a much simpler construction than those of D. Oldhamium. They are not unfrequently represented in the tangential section by a single cell; and there are rarely more than five or six such cells in each vertical pile. The bark consists of parenchymatous cells arranged in rows perpendicular to the surface. This is also a Lancashire form. A third species of Dictyoxylon discovered in beds of the lower Carboniferous series of Burntisland is named D. Grievii after its discoverer, Mr. Grieve. Its central axis is much deranged, resembling the Heterangium paradoxum of Corda; but several specimens have occurred showing that there was a central vascular axis surrounded by a lax radiating ligneous zone, which in turn was invested by a remarkable cellular bark, which exhibited, both in radiating and tangential sections, a characteristic series of parallel horizontal lines, resulting from a peculiar condition of the cellular parenchyma at the points where they exist. As in D. Oldhamium, vascular bundles ascend through the inner bark. The plants described were connected by the author with some large casts of bark from the Coal-measures, some of which have been described as Sagenaria and Lyginodendra. These specimens have upon their surface elongated lenticular scars arranged as in Lepidodendron; but usually much more elongated in a vertical direction than in that genus, and always lacking the central spots marking the issue of vascular bundles. These areola are not leaf-scars, but casts of depressions in the outer surface of the bark from which the epidermis was removed, and which correspond with the spaces enclosed by the sinuosities of the prosenchymatous layers. The functional uses of these areola are undetermined, and there is as yet much uncertainty as to the true affinities of the genus. On the Structure of Diploxylon, a Plant of the Carboniferous Rocks. By Professor W. C. WILLIAMSON, F.R.S. On the Discovery of a new and very perfect Arachnide from the Tronstone of the Dudley Coal-field. By HENRY WOODWARD, F.G.S., F.Z.S., &c., of the British Museum. The Penny-stone Ironstone of the Coalbrook Dale Coal-field has long been celebrated for yielding, when the nodules are split, impressions of leaves of ferns, Lepidostrobi and other fruits, King-crabs, and the rare remains of Insects. A recently discovered and very perfect specimen of the so-called Curculioides Prestvicii of Buckland (figured in his 'Bridgewater Treatise,' pl. 46", fig. 2), from Dudley, proves this insect to have been one of the "False Scorpions," nearly related to the living genus Phrynus, and not a Coleopterous insect as supposed by Samouelle. The specimen is so preserved as to expose its dorsal and ventral aspect each distinctly preserved upon the two halves of the nodule; the former richly ornamented with rows and rosettes of tubercles, and the latter showing the smooth segmented under-surface of the body bearing the tracheal openings. The hinder border bears four short and stout spines. Four pairs of legs are seen, whose wedgeshaped basal joints meet beneath the cephalothorax, which is very tumid, and has a rather prominent rostrum, probably giving rise to Mr. Samouelle's mistake of calling it a Curculio. Mr. Woodward proposed to name this new genus of "false scorpions Eophrynus, retaining the name Curculioides for C. Ansticii, another example which may truly belong to the Rhynchophora. There are now 44 insects known and described from the Coal-measures, namely 8 Arachnida, 5 Myriapoda, 3 Coleoptera, 13 Orthoptera, 14 Neuroptera, and a doubtful Lepidopterous insect. Relics of the Carboniferous and other old Land-surfaces. Whilst admitting that during particular eras circumstances may have favoured the development of special groups of organisms, which in consequence flourished in greater abundance than the rest, the author deprecated the idea of the prevalence of peculiar conditions at any time since the advent of organic life on the globe. Although in the earlier Palæozoic rocks we have little or no evidences of land, yet the fact of stratified deposits being formed at the bottom of the sea is positive evidence of the waste of neighbouring land-surfaces, which must have been always in existence. And further, if conditions in the sea were favourable to the development of abundance of animal life, those on the land were in all probability equally so. Mr. Woodward referred to the abundance of evidence of land-surfaces everywhere, both in Quaternary and in Tertiary times, the former differing but little, save in the geographical distribution of its fauna, from that of the present day, the latter differing more and more from the existing fauna and flora, and also in its relation to existing lands. When, however, the base of the Tertiaries is reached, the land-surfaces are divided by greater marine accumulations; nevertheless we find, both in Europe and America, freshwater deposits with remains of land-plants and animals often in rich abundance. Even the truly marine deposits (such as the Chalk) testify to the presence of land by the fossil remains of Pterodactyles, Cheloniæ, and other shore-dwelling reptiles. Mr. Woodward instanced the Wealden beds, the Purbeck limestone, and Oolitic plant-shales as affording abundant proofs of Mesozoic lands, whilst truly marine accumulations (such as the Solenhofen limestone) contain swarms of insects, flying lizards, and a true bird, with branches of Coniferæ and other trees to tell of a landfauna adjacent to its waters. The author noticed the earliest mammals found in the Triassic bone-beds of Stuttgart and Somerset, and the ripple-marked slabs covered with bird-like tracks and Labyrinthodont foot-marks, telling of the denizens of the old Triassic sea shores and lakes. He next described the coal-period, with its stores of land-plants and Reptilia, both aquatic and terrestrial, its insects and mollusca. He controverted the arguments of Dr. T. Sterry Hunt as to the exceptional condition of the atmosphere of the Coal-period, and showed that the presence of animal life disproved the existence of an atmosphere charged with carbonic acid gas, and that plants would not be benefitted thereby, as Dr. Hunt supposed. With respect to the wide distribution of coal, Mr. Woodward pointed out that it was not necessary to assume that all coal was formed throughout the world during one and the same epoch, but, on the contrary, he showed that coal might be alike as regards its fauna and flora, and yet of very widely different ages. 1871. 8 He advocated the formation of coal from the slow but sure accumulation of peatgrowth, as that mode of conservation of vegetable matter was proved to be the most certain to yield pure hydrocarbons such as we find the coal to consist of, unmixed with foreign matter. Such pure accumulations could not (in the opinion of the author) be formed in river-valleys, deltas of great rivers, or in marine swamps and marshes, but on wide plains covered with a thick vegetation, and tending, by its clayey soil, to check drainage and produce peat-growth. Mr. Woodward referred to the discoveries of Devonian land-plants and insects by Dr. Dawson in North America, and to the occurrence of seed-spores of landplants in Silurian strata; he suggested that the veins of Graphite may be accepted as evidence of old coal-seams, altered by heat and pressure; and that the oilsprings in the Silurian rocks may be due to the destructive distillation of old coalbeds in Nature's own retort. BIOLOGY. Address by Dr. ALLEN THOMSON, F.R.SS. L. & E., Professor of Anatomy in the University of Glasgow, President of the Section. IN now opening the Meetings of the Biological Section, it is my first duty to express my deep sense of the honour which has been conferred upon me in appointing me to preside over its deliberations. I trust that my grateful acceptance of the office will not appear to be an assumption on my part of more than a partial connexion with the very wide field of science included under the term Biology. I should gladly have embraced the opportunity now afforded me of conforming to a custom which has of late become almost the rule with the Presidents of Sections, viz. that of bringing under your review a notice of the more valuable discoveries with which our science has been enriched in recent times, were it not that the subjects which I might have been disposed to select would require an amount of detail in each which would necessarily limit greatly their number, and that any attempt to overtake the whole range of this widespread department of science, even in the most general remarks, would be equally presumptuous and futile on the part of one whose attention has been restricted mainly to one of its divisions. I am further embarrassed in the choice of topics for general remark by the circumstance that many of those upon which I might have ventured to address you have been most ably treated of by my predecessors, as, for example, in the Sectional Addresses of Dr. Acland, Dr. Sharpey, Mr. Berkeley, Dr. Humphry, and Dr. Rolleston, as well as in the General Presidential Addresses of Dr. Hooker and Professor Huxley. I must content myself, therefore, with endeavouring to convey to you some of the ideas which arise in my mind in looking back from the present upon the state of Biological Science at the time when, forty years since, the Meetings of the British Association commenced-a period which I am tempted to particularize from its happening to coincide very nearly with that at which I began my career as a public teacher in one of the departments of Biology in this city. In the few remarks which I shall make, it will be my object to show the prodigious advance which has taken place not only in the knowledge of our subject as a whole, but also in the ascertained relation of its parts to each other, and in the place which Biological knowledge has gained in the estimation of the educated part of the community, and the consequent increase in the freedom with which the search after truth is now asserted in this as in other departments of science. And first, in connexion with the distribution of the various subjects which are included under this Section, I may remark that the general title under which the whole Section D has met since 1866, viz. Biology, seems to be advantageous both from its convenience, and as tending to promote the greater consolidation of our science, and a juster appreciation of the relation of its several parts. It may be that, looking merely to the derivation of the term, it is strictly more nearly synony mous with physiology in the sense in which that word has been for a long time employed, and therefore designating the science of life, rather than the description of the living beings in which it is manifested. But until a better or more comprehensive term be found, we may accept that of biology under the general definition of "the science of life and of living beings," or as comprehending the history of the whole range of organic nature-vegetable as well as animal. The propriety of the adoption of such a general term is further shown by a glance at the changes which the titles and distribution of the subordinate departments of this Section have undergone during the period of the existence of the Association. During the first four years of this period the Section met under the combined designation of Zoology and Botany, Physiology and Anatomy-words sufficiently clearly indicating the scope of its subjects of investigation. In the next ten years a connexion with Medicine was recognized by the establishment of a subsection or department of Medical Science, in which, however, scientific anatomy and physiology formed the most prominent topics, though not to the exclusion of more strictly medical and surgical or professional subjects. During the next decade, or from the year 1845 to 1854, we find along with Zoology and Botany a subsection of Physiology, and in several years of the same time along with the latter a separate department of Ethnology. In the eleven years which extended from 1855 to 1865, the branch of Ethnology was associated with Geography in Section E. More recently, or since the arrangement which was comnienced in 1866, the Section Biology has included, with some slight variation, the whole of its subjects in three departments. Under one of these are brought all investigations in Anatomy and Physiology of a general kind, thus embracing the whole range of these sciences when without special application. A second of these departments has been occupied with the extensive subjects of Botany and Zoology; while the third has been devoted to the subject of Anthropology, in which all researches having a special reference to the structure and functions or life-history of man have been received and discussed. Such I understand to be the arrangement under which we shall meet on this occasion. At the conclusion of my remarks, therefore, the department of Anatomy and Physiology will remain with me in this room; while that of Zoology and Botany, on the one hand, and of Anthropology on the other, will adjourn to the apartments which have been provided for them respectively. With regard to the position of Anthropology, as including Ethnology, and comprehending the whole natural history of man, there may be still some differences of opinion, according to the point of view from which its phenomena are regarded: as by some they may be viewed chiefly in relation to the bodily structure and functions of individuals or numbers of men; or as by others they may be considered more directly with reference to their national character and history, and the affinities of languages and customs; or by a third set of inquirers, as bearing more immediately upon the origin of man and his relation to animals. As the first and third of these sets of topics entirely belong to Biology, and as those parts of the second set which do not properly fall under that branch may with propriety find a place under Geography or Statistics, I feel inclined to adhere to the distinct recognition of a department of Anthropology, in its present form; and I think that the suitableness of this arrangement is apparent, from the nature and number of the appropriate reports and communications which have been received under the last distribution of the subjects. The beneficial influence of the British Association in promoting biological research is shown by the fact that the number of the communications to the Sections, received annually has been nearly doubled in the course of the last twenty years. And this influence has doubtless been materially assisted by the contributions in money made by the Association in aid of various biological investigations; for it appears that, out of the whole sum of nearly £34,500 contributed by the Association to the promotion of scientific research, about £2800 has been devoted to biological purposes, to which it would be fair to add a part at least of the grants for Paleontological researches, many of which must be acknowledged to stand in close relation to Biology. The enormous extent of knowledge and research in the various departments of Biology has become a serious impediment to its more complete study, and leads to |