The first section of the paper is concerned with a detailed account of the structure of the classic Schiehallion area. The account is extended to the flat belt via the Glen Lyon-Ben Lawers area. It is demonstrated that major D1 folds involve the whole of the Appin and Argyll groups and now face SE. However, the original D1 folds were probably open upward-facing folds which have been refolded and modified by the dominant D2 deformation. D2 is represented by an antiformal complex which culminates downwards in the Boundary Slide, a zone of strong deformation associated with NW translation of Dalradian over the ‘young Moine’ rocks. D3 has been responsible for the rotation of the originally flat D2 structures into their present ‘steep’ attitudes N of Glen Lyon. D4 is represented by the strike-swing of the lower Dalradian formations, possibly related to early movements on the two major faults that bound the area. The concept of a D1 Tay Nappe which roots in the ‘young Moine’ to the N is retained, although the scale and flat attitude of that fold is regarded as in part a product of D2.

The work described in the following pages was carried out in the Department of Zoology of the University of Edinburgh and at the Marine Laboratory, Plymouth. It is my pleasant task to thank the British Association for the use of their table at Plymouth, and the staffs of the Plymouth Laboratory and of the Department of Zoology at Edinburgh for help and advice; in particular, I would thank Professor J. H. Ashworth, F.R.S., under whose direction the work was carried out, for his continued aid and interest at every stage.

The animal which was used throughout the investigation was the common razor shellfish or spoutfish of our coasts, Ensis siliqua (Schumacher). The specimens studied at Edinburgh were obtained from a sandy bay at Port Seton, about ten miles below Edinburgh on the Firth of Forth; at Plymouth they were got from the east bank of the Salcombe Estuary. At both places razor shellfish were abundant at the low-water mark of spring tides, and at both Ensis siliqua was the sole species obtained.

For histological purposes small- whole animals, which were very rare, and small pieces of tissue were fixed in Bouin's fluid, in E. Allen's chromic Bouin with urea, or in corrosive sublimate and acetic mixture, and sections, cut 8 μ and 12 μ thick, were stained with Heidenhain's iron alum hæmatoxylin or in Delafield's hæmatoxylin and counter-stained with eosin.

The mechanisms by which Cordilleran plutons are emplaced vary widely. However, the present authors have examined a series of plutons ranging from 2-35 km emplacement depth that have many common features, which suggest that downward transport of host rock is the most important mechanism during magma ascent and pluton emplacement. Many of these Cordilleran plutons preserve gently dipping, unfaulted roofs attached to steep walls bordered by narrow ductile aureoles. Flat lying roof strata commonly roll over into steeply dipping rim monoclines and anticlines that young towards and follow the pluton margin. Field observations suggest that such rim monoclines and anticlines formed due to gravitationally driven roof collapse and channel flow along margins. In the examples in this paper, pluton walls are often comprised of narrow steeply dipping ductile aureoles in which the intensity of strain increases downward. Aureole ductile strains are insufficient to account for the volume of magma emplaced, and are typically <40% of pluton volume. However, when aureole strain is combined with minimum estimates of stoping and host rock rotation during rim monoclines formation, sufficient space can be created. The examples suggest that gravitationally driven downward host rock transport by stoping and rigid rotations along roofs and walls and by focused channel flow by ductile strain along walls are common processes during the rise of Cordilleran plutons, and is one process that contributes to crustal thickening and the growth of crustal roots.

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.

The redox state variation of orogenic granitoids along convergent plate margins is examined in the Phanerozoic Circum-Pacific Belt and in some Cryptozoic terranes. The Phanerozoic granitoids of the NW and NE Pacific Rims can be divided into reduced ilmenite series occurring in the accretionary terranes with compressional tectonic setting, and oxidised magnetite series intruding crystalline basements under extensional to intermediate regional stress regime. The ilmenite-series granitoids have negative but the magnetite series have positive δ34S values, which show a positive correlation with magnetic susceptibility of the granitoids. The negative δ34S sulphur originated in biogenic sulphur from accreted pelitic sediments and positive δ34S values show that sulphate sulphur migrated from seawater through subduction processes. The whole rock δ18O values are higher than 8 permil in the ilmenite series, but lower than 8 permil in the magnetite series, and as a whole show negative correlation with the magnetic susceptibility of the granitoids. The higher δ18O values reflect those of accreted sediments, whilst the lower δ18O values represent magmatic values of an oxidised mafic protolith at depth.

The predominance of ilmenite-series granitoids of the NW Pacific rim can be explained by well-developed accretionary terranes in which mafic magmas from depth mingled with felsic magmas from the accretionary complex to form granodioritic magmas, whilst that of magnetite-series granitoids is postulated to be oxidised igneous sources for the magma generation and an extensional and/or intermediate tectonic setting for the magma ascent. The absence of the accretionary wedges by tectonic erosion and/or no fore-arc sedimentation also helped to form magnetite-series granitoids. Potassic granitoids are generally of oxidised type. A-type granites in late orogenic environments also belong to the magnetite series. Adakitic high-Sr/Y granitoids are oxidised in the Mesozoic–Cenozoic but are reduced in the Archaean TTG, reflecting the redox state of the then-current sea-floor environment. The oldest magnetite-series granite so far known is the 3105 Ma-old biotite granite of the Nelspruit batholith, South Africa.

The fossil record of unquestionable decapod remains dates back to Permo Triassic times. Evaluation of all available data from the fossil record, trace fossils and facies reveals various trends within the evolution of Mesozoic decapods, and its relation to their ecology. One of these trends is the protection of the long vulnerable abdomen. The most successful method, gradual reduction and inflection of the abdomen against the ventral cephalothorax, led to the Brachyura. Brachyurans exhibit the broadest spectrum of habitat adaptions.

Textural and mineralogical features in the high-K calc-alkaline Kozárovice granodiorite (Hercynian Central Bohemian Pluton, Bohemian Massif) and associated small quartz monzonite masses imply that mixing between acid (granodioritic) and basic (monzonitic/monzogabbroic) magmas was locally petrogenetically significant.

Net veining, with acicular apatite and numerous lath-shaped plagioclase crystals present in the quartz monzonite, and abundant mafic microgranular enclaves (MME) in the granodiorite, indicate that as the monzonitic magma was injected into the granodioritic magma chamber, it rapidly cooled and was partly disintegrated by the melt already present. Evidence from cathodoluminescence suggests that the two magmas exchanged early-formed plagioclase crystals. In the quartz monzonite, granodiorite-derived crystals were overgrown by narrow calcic zones, followed by broad, normally zoned sodic rims. In the granodiorite, plagioclase crystals with calcic cores overgrown by normally zoned sodic rims are interpreted as xenocrysts from the monzonite. After thermal adjustment, crystallisation of the monzonitic magma ceased relatively slowly, forming quartz and K-feldspar oikocrysts.

Although the whole-rock geochemistry of the quartz monzonite and the MME support magma mixing, major- and trace-element based modelling of the host granodiorite has previously indicated an origin dominated by assimilation and fractional crystallisation. Magma mixing therefore seems to represent a local modifying influence rather than the primary petrogenetic process.

The observations recorded in the following pages were begun upwards of four years ago. In the course of an investigation into the anatomy and physiology of the central nervous system of the monkey, it was deemed necessary, amongst other things, to note whether the lesions established had influenced the temperature of the affected limbs. On consulting the chapter on “Animal Heat” by Pembrey in Schäfer's Text-booh of Physiology, and Richet's article “Chaleur,” in the Dictionnaire de Physiologie to find what the normal temperature of the monkey was, it was discovered that very few observations on the temperature of this animal had been made. Considering the high position which the monkey occupies in the animal scale, it seemed to us that this was an omission which we might with advantage do something to remedy; we decided therefore to avail ourselves of the material at our disposal, and to record the temperature of such healthy monkeys as should come into the laboratory from time to time.

Kentuckia, from the basal Carboniferous, is the earliest bony fish in which neurocranium and dermal skeleton are well known. The dermal bones show that it belongs to the central family Palæoniscidæ of Berg. They have no obvious generalised characters, however, and are chiefly distinguished by a deeply embayed hind margin to the skull roof, no dermohyals and an elongated postorbital bone. These features suggest a greater affinity with the few known Devonian types than with those of the Carboniferous.

The neurocranium has a considerable likeness to Watson's Kansas Palæoniscids A and B, and confirm Watson's view that this is the fundamental type of actinopterygian cranium. Kentuckia is slightly more generalised than the others in having a paired myodome and a less excavated dorsal surface. The notochord in all three has a long anterior extension like that shown in Pteronisculus (Glaucolepis) of the Eo-Trias by Nielsen. This latter fish is similar to the earlier ones if allowance is made for a greater proportion of cartilage. In the discussion reference is also made to the following: the degree of ossification of these fishes, the nature of the cranial fissure and its homologues, the distribution of the third, fourth, fifth and seventh nerves, and the origin of the cranial wall in the orbitotemporal region.

Certain additions are made to Watson's account of Palæoniscids A and B, particularly concerning the interior of the braincase. A new form, C, is also described.

Branchiopods are primitive crustaceans whose history extends back at least to the Devonian, yet some are highly successful today. Most fossil branchiopods do not show many features that lead to an understanding of function, but the Devonian lipostracan Lepidocaris is an exception. Recent work on living branchiopods, especially anostracans and anomopod cladocerans, enables Lepidocaris to be considered as a living animal. Work on extant anostracan nauplii also makes it possible to deduce how its larval stages swam and collected food.

Other early crustaceans are briefly considered and comments are made on the concept of “living fossils”. While rates of morphological and genomic evolution are often discordant, the concept is still useful. Some branchiopods, such as the Notostraca, display remarkable morphological stasis: on the basis of morphology, a Triassic and a present-day form appear to be conspecific. The latter may be referred to as a “living fossil”.

The outstanding morphological stasis of the crustacean nauplius is noted. Its existence in Cambrian times, deducible from its distribution among modern taxa, has been confirmed by Müller's finds. Such stasis, involving part of the genome of organisms whose adults display enormous adaptive radiation, has persisted with relatively small modifications since before the commencement of the entire radiation of vertebrates.

A Study of the oögenesis and maturation in four species of melaniid snails, viz. Melanoides tuberculatus—diploid race 2n = 32, M. tuberculatus—polyploid race with 90-94 chromosomes, M. lineatus—polyploid with 71-73 chromosomes and M. scabra—polyploid with 76-78 chromosomes, showed these species to be thelytokous. These are instances of ameiotic parthenogenesis with two equational maturation divisions and are recorded for the first time in molluscs, the only other known instance in the animal kingdom being shown by the cockroach, Pycnoscelus surinamensis. The other parthenogenetic molluscs known so far, viz. Potamopyrgus jenkinsi and Campeloma rufum are also of the ameiotic type but have a single maturation division. No males were ever found in the diploid race of M. tuberculatus and in M. scabra. In the polyploid race of M. tuberculatus and in M. lineatus sporadic males occur, forming about 3 per cent of the population in the former and 0·01 per cent in the latter. Further evidence for ameiotic parthenogenesis is provided by the complete absence of sperms in the receptaculum seminis and brood pouch and also by the absence of sperm elements or any fusion of nuclei in the egg. The chromosome numbers in the different species have been determined from maturation metaphase and have been checked from first cleavage metaphase. Polyploidy is associated with parthenogenesis in three of these species.

Oögonial cell divisions are generally absent. Only three oögonial metaphase plates were seen in the diploid race of M. tuberculatus and one in M. lineatus although a very large number of preparations of the ovary were examined. The author holds the view that the maturation prophase is the continuation of the oögonial early metaphase stage without intervening metaphase, anaphase and telophase. The prochromosomes seen in proleptotene stage are already split and the succeeding stages are characterized by the absence of zygotene, pachytene or any pairing and chiasma formation. Each split chromosome behaves functionally like a bivalent throughout maturation prophase and separates into daughter chromosomes at the first division. The second division is equational as in normal maturation.

The hypothesis that tetrapods evolved from elpistostegids during the Frasnian, in a predominantly aquatic context, has been challenged by the discovery of Middle Devonian tetrapod trackways predating the earliest body fossils of both elpistostegids and tetrapods. Here I present a new hypothesis based on an overview of the trace fossil and body fossil evidence. The trace fossils demonstrate that tetrapods were capable of performing subaerial lateral sequence walks before the end of the Middle Devonian. The derived morphological characters of elpistostegids and Devonian tetrapods are related to substrate locomotion, weight support and aerial vision, and thus to terrestrial competence, but the retention of lateral-line canals, gills and fin rays shows that they remained closely tied to the water. Elpistostegids and tetrapods both evolved no later than the beginning of the Middle Devonian. The earliest tetrapod records come from inland river basins, sabkha plains and ephemeral coastal lakes that preserve few, if any, body fossils; contemporary elpistostegids occur in deltas and the lower reaches of permanent rivers where body fossils are preserved. During the Frasnian, elpistostegids disappear and these riverine-deltaic environments are colonised by tetrapods. This replacement has, in the past, been misinterpreted as the origin of tetrapods.

Cyrtoctenus wittebergensis sp. nov. is described from a unique holotype from the Witteberg Group of the Cape Supergroup. It is a giant hibbertopteroid eurypterid having combs and specialised movable spines of crytoctenid type (Størmer & Waterston 1968) on the more distal podomeres of the second to fourth prosomal appendages. The function of the combs and their associated movable spines is discussed and it is suggested that together they formed a unique adaptation of eurypterid structures to sweep filter-feeding, the combs forming the filters and the spines the cleaners. The digestive tract is remarkably preserved and shows a spiral valve, posterior to the stomach, which is interpreted as an adaptive feature in this large arthropod to increase the absorptive area of the gut.

The new evidence provided by the South African specimen has required the re-interpretation of the disarticulated Cyrtoctenus specimens previously described from Europe. Disjecta membra recently obtained from the Tournaisian of Foulden, Berwickshire, which may belong to Cyrtoctenus, are described and show characters previously unknown in Scottish material but similar to certain features in the South African specimen.

The taxonomic relationships within the Hibbertopteroidea are discussed in the light of the new combination of characters found in C. wittebergensis. Two families are recognised in the superfamily, the Hibbertopteridae, including Hibbertopterus and Campylocephalus, and the new family Cyrtoctenidae which is here erected to include Cyrtoctenus, Dunsopterus and possibly also Hastimima.

The first of this series of papers, that on the “Fossil Plants collected during the sinking of the shaft of the Hamstead Colliery, Great Barr, near Birmingham,” was published in 1888, and the second, dealing with the “Fossil Flora of the Coal Field of the Potteries,” in 1891.

Since that date the North Staffordshire Coal Field has been re-surveyed by members of the Geological Survey, and the result of this re-examination of the geology of the Potteries Coal Field was the classification of the strata into several well-defined groups.

Material of a coccosteid fish, from various localities in Caithness, is described as Dickosteus threiplandi n.g., n.sp. The fish has previously been confused with Coccosteus cuspidatus Miller ex Ag. ( = Coccosteus decipiens Ag.). A diagnosis of this new form is given and comparisons made with Coccosteus show that it is quite distinct. Coccosteus fletti Watson is also redescribed and referred to the new genus Watsonosteus. The phylogenetic relations and stratigraphical distribution of these two genera are considered, and it is shown that Dickosteus occurs in Caithness in the Thurso Flagstone Group above the Achanarras horizon, apparently replacing Coccosteus, and has a similar range in Orkney. Watsonosteus is characteristic of the Eday Flags. The stratigraphy of the Thurso Flagstone Group is critically reviewed and compared with the Orkney succession; the Ackergill Beds are shown to be the probable lateral equivalents of the Mey Beds, and the consequences of this are examined.

The upper half of the Archerbeck Borehole contains a continuous Mississippian succession from the late Asbian (late Viséan) to the Pendleian (early Serpukhovian), with numerous limestone horizons. The borehole sequence lies within the Solway Basin (western end of the Northumberland Trough) and bridges the successions between the Midland Valley of Scotland and the Pennines (northern England). The rich foraminiferal and algal assemblages are compared to those described by previous authors, and genera as well as species are updated as far as is possible. In addition, some other overlooked or underestimated taxa have been identified and illustrated, which improve notably the biostratigraphic resolution of the Archerbeck Borehole succession. Within the abundant foraminiferal assemblages can be highlighted the richness and diversity of representatives of the family Archaediscidae. In general, the succession developed in the Archerbeck Borehole is closely comparable with that in the Alston Block of northern England. The Asbian/Brigantian transition mimics that observed in the Janny Wood boundary stratotype section, with clear late Asbian horizons (lower part of the Archerbeck Beds), transitional beds (middle and upper parts of the Archerbeck Beds), and Brigantian limestones (from the Cornet Limestone upwards). The base of the early Brigantian is placed at the base of the Cornet Limestone (equivalent to the Lower Peghorn Limestone in the Alston Block). The base of the late Brigantian is placed at the base of the Gastropod Limestone (equivalent to the Scar Limestone Member in northern England), and the base of the Pendleian is repositioned at the base of the Under Limestone (equivalent to the Four Fathom Limestone Member in northern England). Throughout, the borehole, protista and microfloral elements are abundant, which allows the recognition of Assemblages 4 to 10, previously recognised in northern England and the Midland Valley of Scotland. Furthermore, other local assemblages are recognised and related to palaeoecological controls, although they do not represent any improvement in biostratigraphical resolution.

Progress in the understanding of the volumes and viscosities of granitic and related pegmatitic melts generated by experimental studies are reviewed. The results of a series of investigations of the volumes and viscosities of melts derived from a haplogranitic base composition, HPG8, located near the 2 kbar water-saturated minimum melt composition in the albite—orthoclase—silica system are discussed. Melt volumes, obtained using a combination of dilatometric and calorimetric methods at 1 atm and relatively low temperatures yield an internally consistent set of partial molar volumes for 18 components in granitic melts. These partial molar volumes, combined with an estimate for water, allow the estimation of melt densities for granitic and related pegmatitic magmas.

Melt viscosities, obtained using a combination of high and low range viscometry techniques, provide a template for the estimation of melt viscosities in more complex natural systems. The parameterisation of the non-Arrhenian temperature-dependence of the viscosity of such melts is presented, together with some structural implications of the variation of melt viscosity with temperature and composition. Outstanding questions related to the PVT equation of state of granitic melts and to the mechanical response to shear stresses are discussed, with an outlook for the experimental solutions to those questions in the next few years.

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.

The trilobite fauna of the basal Didymograptus superstes Mudstones (Nemagraptus gracilis zone) at Aldons Quarry is described. The fauna is large, consisting of 68 species, of which 12 are new, belonging to 47 genera. The fauna bears a much closer resemblance to that of the Albany mudstones than to that of the platy upper Stinchar Limestone: this is attributed to environmental control. The strong North American stamp of Barr Group faunas is at a maximum: Stenoblepharum, Raymondella, Chomatopyge and Miraspis appear for the first time in the Girvan District.

A new crustacean, Castracollis wilsonae is described from a loose block of the Early Devonian Rhynie chert, found in the vicinity of Rhynie, Aberdeenshire, Scotland. It differs markedly from Lepidocaris rhyniensis, Scourfield 1926, the only other crustacean found in the Rhynie chert.

The material comprises complete individuals up to 8 mm long and fragmentary remains. The head is normally damaged and detached from the body, and damage to the anterior of the trunk suggests the specimens are exuviae. The head appears domed with a labrum, robust mandibles, and long biramous antennae. A few specimens exhibit a probable detached cephalo-thoracicshield. The trunk is multi-segmented, comprising similar ring-like somites. The thorax variably comprises up to 26 segments. The anterior 11 segments possess similar long, phyllopodous appendages, the remainder variably possess 10 to 15 phyllopodous appendages with a disposition of one per somite. The abdomen comprises up to 28 apodous segments. The posterior of the body comprises a telson with two furcal rami.

The crustacean is most probably a calmanostracan branchiopod. It occurs associated with Lepidocaris, charophytes, cyanobacteria and coprolites within a ‘clotted’ chert texture, indicating subaqueous deposition, most probably in a temporary freshwater pool in an area of surficial hydrothermal activity.