Elsewhere two of the present authors (Davies and Francis, 1941) have expressed the opinion that a specialised cardiac conducting system, consisting of nodal and Purkinje fibres, is a newly evolved one in birds and mammals. The general morphology and topography of this system in the heart of the bird (Davies, 1930 a, 1930 b) is similar to that in the heart of the eutherian mammal, and we have postulated (Davies and Francis, 1941) that the system has undergone parallel evolution in these two classes of homoiothermal vertebrates in response to functional requirements, and that in particular its presence can be correlated with the rapidity of the heart-rate in proportion to its size. On the other hand, Keith and Flack (1907), Keith and Mackenzie (1910), and Mackenzie (1913) maintain that the sinu-atrial node, atrio-ventricular node, and atrio-ventricular bundle of the mammalian heart are remnants of more extensive tissues of similar structure in the hearts of lower vertebrates. They trace the evolution of the conducting system of the mammalian heart from a simpler and more definite form which they described in the fish, and state that as one ascends the animal scale the concentration and reduction of nodal tissue becomes more marked. We ourselves (Davies and Francis, 1941) have failed to find any nodal or Purkinje fibres in any part of the hearts of the following cold-blooded vertebrates: fish (eel, gurnard), amphibia (salamander, frog), and reptiles (tortoise, Mississippi alligator, Sphenodon). We therefore believe that, whereas the ordinary cardiac muscle is able to conduct the impulse for cardiac contraction quickly enough in these slowly contracting cold-blooded vertebrate hearts, a specially developed system is evolved in the much more rapidly beating hearts of birds and mammals. Amongst mammals themselves, the nodal and Purkinje fibres of the monotreme heart (Davies, 1931) have the same general disposition as those in the eutherian mammal. The present work is concerned with the conducting system of the heart of the remaining sub-class of mammalia, namely the Didelphia. No previous detailed study of this system in the marsupial heart has been made.

Five orthopteran specimens from the uppermost Middle–lowermost Upper Jurassic of Daohugou, Inner Mongolia, China are described and attributed to the genus Sigmaboilus Fang, Zhang & Wang, 2007 (Prophalangopsidae); and a new species, S. calophlebius sp. nov., is established herein. The diagnostic characters for Sigmaboilus are revised and a key to species of Sigmaboilus, based on male forewings, is provided. Intraspecific variation in forewings of this genus is also discussed.

Ramsay Heatley Traquair, the eminent Victorian Scottish palaeoichthyologist and museum curator, procured an extensive collection of Palaeozoic fishes from across Scotland with the help of local miners and quarrymen. One very productive locality near Edinburgh was Loanhead. Traquair described numerous fossil fish from this Serpukhovian site, including four lungfish taxa: Ctenodus interruptus, Sagenodus quinquecostatus, Uronemus splendens and Ctenodus angustulus. The first three are now quite well known, but the fourth was only briefly described and never figured. It is based entirely on tooth plates, which are unusual both in their very small size and the arrangement of the tooth ridges. They lack the diagnostic characters of Ctenodus tooth plates and are here renamed Clackodus angustulus. A further taxon, Conchopoma sp., has recently been identified. Represented by a spade-shaped parasphenoid and denticulated jaw elements, it is the earliest known occurrence of the genus, extending its range into the Mississippian. A sixth taxon may be represented by an isolated parasphenoid bearing an anterior process, previously only seen in Devonian lungfish. The presence of up to six lungfish taxa at a single locality is unprecedented in the Carboniferous and indicates that the high level of lungfish diversity encountered in the Tournaisian of the Scottish Borders continued throughout the Mississippian, adding to the growing evidence that post-Devonian lungfish evolution was not as limited as previously proposed. This may have been due to changes in tooth plate growth, enabling greater variation in dentition and diet. In most Devonian taxa, tooth plate growth can be explained by comparison with that in extant forms, but analysis of Carboniferous tooth plates suggest growth was different in many taxa, possibly based on more than one pioneer tooth, allowing for novel patterns of tooth ridges and different types of teeth to develop on the same plate.

To understand the physico-chemical processes associated with migmatisation is an interesting petrological problem. New developments in microfluidics and chaotic mixing experiments have helped us to better perceive these processes from the migmatic rocks of the Proterozoic Chotanagpur Granite Gneiss Complex (CGGC), eastern India. The migmatic rocks of CGGC have preserved folded leucocratic veins in amphibolites representing viscous folding. The viscous folding phenomenon occurred due to the interaction between leucosome and melanosome. Based on textural features and mineral chemical data interpretations, we infer that when granitic and pegmatitic magmas intruded the gneissic rocks and amphibolites of our study area, diffusion of heat and volatiles from the hotter felsic magmas to the colder country rocks initiated partial melting in the amphibolites, forming melanosomes. After their formation, the highly viscous felsic magmas veined into the melanosomes, by progressively melting them and then interacting, leading to chaotic mixing dynamics. The development of chaotic mixing allowed the leucosome to venture into the melanosome as veins by stretching and folding dynamics. As the leucocratic veins or leucosome traversed through the partially molten rock or melanosome due to advection, the veins underwent viscous folding owing to the exertion of compressional stress brought about by the viscosity difference between the two mediums. The occurrence of viscous folding exponentially increased the contact area between the leucosome and the melanosome, eventually leading to enhanced diffusion and augmented mixing between the two mediums. Evidence of mixing through elemental diffusion is well documented by the compositions of amphibole and biotite occurring in the leucosome and melanosome. These minerals show substitution of magnesium and ferrous ion that show linear variation between the endmember compositions.

The feature distinguishing typical angiosperms from gymnosperms is that their ovules are enclosed before pollination. Bennettitales were formerly related to angiosperms because of the flower-like organisation of the former's reproductive organs. There is little information on how the naked ovules of Bennettitales became enclosed in angiosperms because fossil evidence for such a transition, if it exists, has not been described. Here, we report a reproductive organ, Zhangwuia gen. nov., from the Middle Jurassic of Inner Mongolia, China. Like many Bennettitales, the arrangement of the foliar parts around the female part in Zhangwuia demonstrates a resemblance to typical angiosperm flowers. It is noteworthy that the ovule is secluded from the exterior space in Zhangwuia, therefore implying the existence of angio-ovuly. Although Bennettitales have been related to angiosperms for more than a hundred years, their way of ovule-enclosing was not previously revealed. The discovery of Zhangwuia prompts a rethinking of the relationship between Bennettitales and angiosperms, as well as of the origin of angiosperms.

In a previous paper on the anatomy and affinity of Platyzoma microphyllum R. Br. (Trans. Roy. Soc. Edin., vol. li, No. 20, 1916), the structure of a single herbarium specimen of this rare Australian fern, collected by Professor Baldwin Spencer in 1902, at Boorroololoo, N.T., was described. Attention was directed in particular to the remarkable heterophylly, the anomalous stelar structure, and the unique sporangia and spores. The facts detailed made it difficult to indicate any known fern with which Platyzoma could be reasonably compared. They might be considered to suggest a probable derivative position for Platyzoma from some Gleicheniaceous source; but their divergence from the Gleichenia characters was so pronounced that it seemed impossible to retain a view of close affinity between Gleichenia and Platyzoma.

Nice is situated on the shore of the Mediterranean, in lat. 43° 41′ 16″ N. and long, east of Greenwich 7° 16′ 37″. The county of which Nice is the capital, was comprehended in the Roman province of the Maritime Alps: it was included, while under the influence of France, in a department to which the same name was given; and now, it is restored to the sovereignty of Piémont, it may be considered as bounded on the west by the Var, which separates it from France, on the north and east by the mountains of Dauphiné and Piémont, and on the south, it is washed by the Mediterranean.

Since the publication, about a year ago, in the Transactions of this Society, of my paper on the Lower Devonian Fishes of Gemünden, a review of it has appeared in the pages of Science by Professor Bashford Dean, of New York. In this review Professor Dean endeavoured to throw doubts on the correctness of my orientation of the elements of the dermal skeleton of Drepanaspis Gemündenensis, in the following words:—

“Thus, his grounds seem inadequate for distinguishing dorsal and ventral sides. In no specimen figured is the relation of the dorsal lobe of the tail shown convincingly to be continuous with the so-called dorsal aspect; moreover, the eyes occur on the side which Traquair regards as ventral. Unless additional evidence is forthcoming, it would accordingly seem to me more probable that the ‘labial’ of Traquair was the ‘rostral’ plate, a structure which appears constant in Heterostracans.

The inquiries of scientific persons into the various departments of knowledge, have very generally for their sole object the investigation of truth, and the progress of science, without any reference to trade or the usual business of life. Hence to the practical man they seem generally dry and without interest, his mind being directed towards immediate utility, public or individual. Should I in the course of the present inquiry, (which in its essential nature is strictly anatomical and physiological, and can be investigated with advantage only by the anatomist and physiologist,) seem to the strictly scientific to have paid too much attention to practical details, apparently unconnected with the scientific part, and consequently out of the line of my vocation, my apology is, that in the course of the observations, I found this to be unavoidable, although my utmost efforts were made to prevent the inquiry running into this laborious and expensive train; and I entertain a firm belief, that, on a careful perusal of the observations, taking all matters into consideration, it will be found that I could not have done otherwise.

The facts and observations I have now the honour to bring before the Society, were fully made out, and their general correctness ascertained, somewhat more than three years ago. Since that time I have been in the habit of alluding to them, and demonstrating the strictly anatomical part, in my summer course of lectures on comparative anatomy; so that, in short, they may be considered as having, to a certain extent, undergone the ordeal of public opinion. I have thought it right to mention this circumstance, inasmuch as the statements and opinions to be brought forward this evening are contradictory of others which have been promulgated by some anatomists of high standing, and have been received and admitted by naturalists, and by the non-professional, as observations not to be doubted nor controverted; as matters of fact which call for no deeper inquiry; as statements on which unerring doctrinal points might be founded.

Our knowledge of this remarkable genus of freshwater Oligochæta is at present entirely due to Dr Gustav Eisen. Within a year or two of discovering the type species, Sutroa rostrata, Dr Eisen found a second species, evidently referable to the same genus, which has been named Sutroa alpestris. Examples of both of these species have been most kindly forwarded to me by Dr Eisen; and I therefore take the opportunity of offering a few observations upon the structure of the genus, and upon its relations to other Oligochæta, as I am able, in a few matters, to supplement Dr Eisen's papers.

The account given by Eisen of Sutroa alpestris is evidently based upon a study of the living worm; it is therefore very full as regards the vascular system, but not quite so detailed where it concerns the generative organs, which are more conveniently studied by the section method. It is more especially to these organs that I desire to again draw attention.

We naturally regret our failure to convince the British Geological Survey's Southern Uplands team of the nature and importance of the fault which separates Northern and Central Belts, two of the three fundamental divisions of the Southern Uplands terrane which were so brilliantly recognised and defined by their illustrious predecessors (Peach & Home 1899). We welcome the opportunity to clarify the basis of our argument and correct some quite erroneous impressions.

The paper which follows is based in the main on the magnetic records of the observatories at Lerwick (Shetland) and Eskdalemuir (Dumfriesshire), though reference is made to the data of Abinger (Surrey), Sitka (Alaska), Sodankylä (Finland), Colaba (Bombay), and Mauritius, and to records made at different times at Arctic and Antarctic stations. The situation of the Lerwick observatory, just within the auroral zone, might be expected to give to its records an outstanding value in any investigation connected with magnetic storms; the expectation has not been disappointed. The distance between Abinger and Eskdalemuir is about 470 km., and between Eskdalemuir and Lerwick about 550 km.—both quantities small compared with the dimensions of the earth—yet the mean ranges of disturbance at these three places appear to run roughly in the ratio 1:2: 4½. This at once suggests that in the extreme north of the British Isles we approach a zone of exceptional interest from the point of view of magnetic disturbance; and further,-that with suitable magnetic data some attempt might be made to compute the disturbing electric fields, at least in their main features, and possibly to arrive at some idea of any seasonal and annual changes to which these fields may be subject.

The attempt to account for the behaviour of gases by attributing their apparently continuous pressure to exceedingly numerous, but nearly infinitesimal, impacts on the containing vessel is probably very old. It certainly occurs, with some little development, in Hooke's tract of 1676, Lectures de potentiâ restitutivâ, or of Spring; and, somewhat more fully developed, in the Hydrodynamica of D. Bernoulli, 1738. Traces of it are to be found in the writings of Le Sage and Prévost some 80 or 90 years ago. It was recalled to notice in 1847 by Herapath in his Mathematical Physics, and applied, in 1848, by Joule to the calculation of the average speed of the particles in a mass of hydrogen at various temperatures. Joule expressly states that his results are independent of the number of the particles, and of their directions of motion, as also of their mutual collisions.

Teilia Quarry, from which the fossils described in this paper have been collected, is situated about a quarter of a mile north-east of the village of Gwaenysgor, which is distant about five miles from Rhyl and one from Prestatyn.

The geology of the district has been fully described by Mr G. H. Morton, F.G.S., from whose paper the following notes are compiled:—

A considerable part of North Flintshire is occupied by a great development of limestone, which is generally referred to in writings on the subject as “Carboniferous Limestone.” It forms a tract of hilly ground, some of the higher points rising to a height of over 800 feet. These limestones lie immediately beneath the Cefn-y-Fedw sandstones, and occupy a hollow of considerable extent in Silurian strata.

The experiments which form the subject of this paper are designed, in the first place, to test the relation pointed out by Maxwell between Joule's discovery of the lengthening of iron in the direction of magnetisation, and Wiedemann's later researches into the twisting of iron under the influence of longitudinal and circular magnetisations, and, in the second place, to investigate the corresponding properties of nickel.

Echimyidae is the most widely diversified family among hystricognath rodents, both in the number of species and variety of lifestyles. In the Patagonian Subregion of southern South America, extinct echimyids related to living arboreal species (Echimyini) are recorded up to the middle Miocene, whereas all the known southern fossils since the late Miocene are linked to terrestrial and fossorial lineages currently inhabiting the Chacoan open biome in eastern South America. In this work, we describe a new genus of echimyid rodent, Paralonchothrix gen. nov., from the late Miocene of northwestern Argentina and western Brazil. Its single recognised species, Paralonchothrix ponderosus comb. nov., is represented by two hemimandibles. One of them comes from a level of Loma de Las Tapias Formation, underlying a tuff dated at 7.0 ± 0.9 Ma (Huayquerian age, late Miocene); the other specimen comes from the ‘Araucanense’ of Valle de Santa María (type locality, Huayquerian age, late Miocene). A phylogenetic analysis linked Paralonchothrix to Lonchothrix, both being the sister group to Mesomys. Thereby, for the first time, an echimyid linked to living Amazonian arboreal clades is recognised for the late Miocene of southern South America. Paralonchothrix gen. nov. thus represents an exceptional record that raises the need to review the postulated evolutionary pattern for echimyids recorded at high latitudes since the late Miocene. The new genus provides a minimum age (ca.7 Ma) in the fossil record for the divergence between Mesomys and Lonchothrix. The palaeoenvironmental conditions inferred for the late Miocene in western and northwestern Argentina suggest savanna-type environments, with areas with more closed woodlands in peri-Andean valleys. The record of Paralonchothrix gen. nov. supports the hypothesis that this area would have maintained connections with tropical biomes of northern South America during the late Miocene.

For over thirty years problems of stelar structure in the Ferns have claimed the attention of anatomists. By common consent protostely has been recognised as a primitive state. It is seen in all phyla of primitive vascular plants, except the semi-aquatic Equisetales, it figures universally in the juvenile plants of the Filicales, and is maintained in the adult stems of a number of their primitive genera.

But as to the origin of pith, inner phloëm, and inner endodermis, and the steps by which during descent the primitive protostely has in many instances been replaced in the adult by other more complex stelar states, there is no general agreement. On the one hand, the pith, inner phloëm, and inner endodermis have been regarded as purely intrastelar tissues directly referable in origin both in individual plants and descent to the procambial mass of the growing point of the stem.

In 1823 and 1826 I communicated to the Society two papers on the nature and properties of two immiscible fluids, which I discovered, in contact with each other, in the cavities of topaz and other minerals. Although the facts contained in these papers were of so extraordinary a nature as to be received with scepticism by some, and with ridicule by others, yet I am not aware that, during the twenty years which have elapsed since their publication, any person has either repeated my observations, or advanced a single step in the same path of inquiry. In shewing to strangers some of the leading phenomena of the two new fluids, my attention has been frequently recalled to the subject; but it was not till last spring, when I discovered cavities in topaz filled with the most beautiful crystals of various form, that I was induced to undertake a new investigation of their nature and properties.

The mode of growth and increase amongst the Coralligenous Actinozoa in general has been more or less fully treated of by various observers, including such distinguished naturalists as Milne-Edwards, and Haime, Dana, Martin Duncan, Fromentel, Agassiz, and others. I do not, therefore, in the present communication propose to pass the whole of this subject in review, but rather to consider the general and special peculiarities of growth and non-sexual reproduction exhibited by the corals of the Palæozoic Period alone. Many of these peculiarities are of great interest, both from the stand-point of the palæontologist, and also as concerns the systematic zoologist, and they have not yet met with all the attention they deserve. To carry out this inquiry, it will be necessary first to consider the general phenomena exhibited by the Palæozoic corals, as regards their mode of growth and increase. We may then examine the bearing of these phenomena upon various points connected with the classification of these ancient corals, and more especially upon their generic and specific affinities and differences. Finally, we may briefly consider the relations which exist between different parts of a compound corallum as regards their growth, and their influence upon the ultimate form of the colony.