In geochemical diagrams, granitoids define ‘trends’ that reflect increasing differentiation or melting degree. The position of an individual sample in such a trend, whilst linked to the temperature of equilibration, is difficult to interpret. On the other hand, the positions of the trends within the geochemical space (and not the position of a sample within a trend) carry important genetic information, as they reflect the nature of the source (degree of enrichment) and the depth of melting. This paper discusses the interpretation of geochemical trends, to extract information relating to the sources of granitoid magmas and the depth of melting.

%Applying this approach to mid-Archaean granitoids from both the Barberton granite–greenstone terrane (South Africa) and the Pilbara Craton (Australia) reveals two features. The first is the diversity of the group generally referred to as ‘TTGs’ (tonalites, trondhjemites and granodiorites). These appear to be composed of at least three distinct sub-series, one resulting from deep melting of relatively depleted sources, the second from shallower melting of depleted sources, and the third from shallow melting of enriched sources. The second feature is the contrast between the (spatial as well as temporal) distributions and associations of the granites in both cratons.

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.

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.

This research was begun in 1929, and a preliminary account of some of the results of the investigation was published in the Journal of Anatomy, January 1932. It was initiated by the discovery, during experiments on intravitam staining in the guinea-pig, that dye-bearing cells collected in large numbers in the endometrium of the uterus and that their incidence there was cyclic. The first results were obtained in animals injected immediately after parturition and killed at intervals thereafter. In a short series of virgin animals, the series being established by determining the date of heat by the vaginal smear method (Stockard and Papanicolaou, 1917, 1919), practically identical results were obtained.

Lower Old Red Sandstone drainage of the Caledonian mountain chain in the northern British Isles converged in the region of the present North Channel between Scotland and Ireland. Calculations of possible catchment area of this drainage network suggest a major river system c. 530 km in length comparable to parts of the present day drainage network of the Himalayas. Evidence from the Lower Old Red Sandstone sedimentary assemblages in Northern Ireland and Scotland indicates that tributaries flowed NE and SW parallel to the Caledonian mountain front. These tributaries joined a trunk stream which flowed southward from present western Scotland through the southern part of the present Inner Hebrides region, and on through the region of the present North Channel and terminated in the contemporaneous Devonian sea. The coastline of this sea stretched E-W across southern Britain.

The essential drainage system established in Lower Old Red Sandstone times became re- established in Upper Old Red Sandstone times, but with a channel network with palaeoflow to the NE in Scotland. This probably joined a southerly flowing trunk stream in the North Sea region, possibly parallel with the western Scotland-Irish Sea drainage.

Archival and recent boreholes over an area of c. 3 km2 have revealed complex magma-host interaction at the termination of an olivine–dolerite sill in Fife. The sill interior has zones rich in plastically deformed, vesiculated heterogeneous sediment surrounded by amygdaloidal basalt. Sediments at the contacts have been reconstituted and enclose blebs of chilled vesicular basalt. Intrusion into low rank coal seams has produced multicomponent tuffisite. A vertically nested and laterally fingered sill front is envisaged as having propagated down dip under a thin cover (<500 m) of wet Namurian sediments. Non-explosive bulk interaction of fluidised sediment and devolatilising magma occurred at intrusive contacts. Steam explosivity was more vigorous where lobes of magma repeatedly intruded moist lignite, to produce compositionally banded tuffisite rich in basalt clasts and coal fragments. The hydrovolcanic explosions did not give rise to surface eruptions because the low volumes of porewater and the high permeability and low tensile strength of the lignite prevented a build-up of high pressure steam.

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.

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.

Previously described and new specimens of the anthracosaur Silvanerpeton miripedes from the Scottish Viséan of East Kirkton yield important new data which allow us to provide a more complete reconstruction of the skull roof, palate, braincase and lower jaw. A stout sacral rib and an incompletely ossified tarsus with a subquadrangular intermedium are also recorded for the first time. A remarkably well preserved humerus in extensor view shows similarities with humeri of immature specimens of the embolomere Proterogyrinus. A new cladistic analysis, built from combining characters used in two recent matrices, places Silvanerpeton in a basal position relative to embolomeres and more derived stem amniotes. Data from Silvanerpeton inform character polarity near the base of the amniote total group. We discuss some morphofunctional implications of character changes at the root of total group amniotes, acquisition of terrestrial habits, and patterns of early disparity in this clade.

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.

Articulated thelodonts, Loganellia scotica (Traquair), Shielia gen.n. taiti (Stetson), Lanarkia horrida Traquair, L. spinulosa Traquair and Turinia pagei (Powrie) from the Silurian and Devonian of Scotland are re-described. A new species, Lanarkia lanceolata sp.n. from the Wenlock, Lower Silurian, is established. For each species, diagnosis is specified, varieties of scale morphology are given, the branchial area is described and body morphology is detailed. A paired ventral fin in Shielia gen.n. taiti and Lanarkia lanceolata sp.n. has been discovered. A new reconstruction of Loganellia and Shielia, and diagnosis for thelodonts from Scotland are given. The locality list of Scottish agnathans is reviewed and the biostratigraphical distribution discussed.

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 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.

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.

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.

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.

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 Devonian actinopterygian Mimia Gardiner & Bartram (1977) of the Upper Devonian (Frasnian) Gogo Formation of Western Australia, one of the most completely known of all Palaeozoic ray-finned fishes, is renamed Mimipiscis nom. nov. due to preoccupation of the former genus by the butterfly Mimia Evans (1953). Recently acquired data, including the description of newly prepared fossil material, has revealed the presence of a second species in this formerly monotypic genus, as well as previously unreported features of the tail, parasphenoid and ontogenetic variability of type species, Mimipiscis toombsi (Gardiner & Bartram 1977). The second form, Mimipiscis bartrami sp. nov., differs from the contemporary M. toombsi in details of the body shape, squamation, snout, suboperculum and parasphenoid. Phylogenetic analyses recover Mimipiscis and Gogosardina as sister genera within a monophyletic Mimiidae, a clade restricted to the Late Devonian of Western Australia.

The cranial anatomy of the primitive Carboniferous temnospondyl Cochleosaurus bohemicus is described herein from several large, presumably adult, skulls. This new morphological data modifies earlier descriptions by Frič (=Fritsch in post-1876 publications), Romer and Steen, which were based almost entirely on small, subadult Cochleosaurus bohemicus specimens. Recognition of a new autapomorphy for Cochleosaurus bohemicus, (pitting on the ventral surface of the postorbitals) which is independent of ontogenetic change, has facilitated more accurate intra-specific comparisons between cochleosaurids. Cladistic analysis reveals a clear dichotomy separating the Edopoidea from the more derived clade of the remaining temnospondyls, which includes Balanerpeton and Dendrerpeton. The Edopoidea are only weakly supported as a superfamily in this analysis. The Cochleosauridae are a monophyletic family comprising the genera Procochleosaurus, Adamanterpeton, Cochleosaurus and Chenoprosopus.