A Large number of structurally preserved lycopsid axes from the Lower Carboniferous of Scotland are described and designated as a new genus and species. A comparison of this genus with other lycopsids is followed by a discussion of the development of the secondary cortex, and several other interesting structural features.

The last major retreat stages of the ice in Scotland have been correlated with the different periods of vegetational history as shown by pollen diagrams. The end-moraines can be divided into two stages, the first stage being the Perth Readvance Moraine, during which the ice extended outside the Highlands. The Aberdeen Readvance Moraine probably also belongs to the same stage. During the second stage, here called the Highland Readvance, valley glaciers reached to the mouths of the Highland valleys where small moraine ridges were formed.

Samples from mainly lake sediments near the moraine were studied, and the pollen diagrams from them show the general vegetational history of the Late-glacial and Post-glacial periods. The same zones as in other parts of the British Isles are used in the diagrams.

The geological and pollen analytical evidence suggests that the Highland Readvance Moraine was formed during the Late-glacial Zone III, and that the Perth Readvance is older than the Alleröd interstadial. The Highland Readvance can now be correlated with the moraines in Scandinavia, the Alps and North America, where they already have been dated.

The general relationships of the caudal scales in Adpenser sturio and Acipenser ruthenus are considered together with a detailed description of the structure of the scales and corium in A. ruthenus, and a new staining method using purpurin counterstained with aniline blue for differentiating dermal structures in sections is described. A comparison of the caudal scales of sturgeons with those of palæoniscids indicates considerable agreement in form and arrangement between them. Evidence is presented to show that the caudal scales in sturgeons and palæoniscids are distinct from the general body covering of scales, and evidence points to a similar, though reduced, squamation in Lepidosteus and possibly in Polypterus. The importance of the caudal scales in protecting the internal organs in the epichordal lobe of the tail and the significance of the boundary between the body and caudal scales as a hinge for tail flexure is discussed.

Lower Carboniferous eurypterids are rare, and consequently the Scottish eurypterid fauna is of importance, in a world setting, because of the number of species of that age which it contains. Since the Scottish forms were originally described, great advances have been made in our knowledge of the Eurypterida which have made necessary the present critical re-examination of all available Scottish Carboniferous eurypterid specimens. Five species, belonging to four genera, are described and illustrated. Fresh evidence of the anatomy of Campylocephalus scouleri (Hibbert) is presented and the wider issues of eurypterid morphology raised by homology with this specialised species are discussed.

The results are presented of a detailed petrological reconnaissance of a group of picritic minor intrusions in the Hebrides. A substantial amount of new factual data is subjected to a unified treatment as a basis for reference and discussion. Olivine phenocrysts are not appreciably zoned and there is no evidence that they have a reaction relation with the liquid represented by the groundmass. Variations in the size and amount of olivine in individual intrusions are examined in detail and attributed to composite intrusion of differentiated material. A distinctive non-porphyritic facies found in several sills and in one dyke is chemically analyzed. Four analyses from widely separated localities establish this facies as a remarkably invariant, eucritic rock-type. The composition of the groundmass of the picritic rocks is variable and there is no evidence whatever of the participation of basaltic magma in their formation. Although no attempt is made to explain the new data in detail, a comprehensive working hypothesis is formulated. The origin of such picritic intrusions is believed to be due to selective fusion of pre-existing ultrabasic rock. Liquid more basic than normal basalt magmas can be formed by this process. Some re-precipitation of olivine may have preceded final emplacement of a magnesia-rich liquid which contained xenocrysts, mainly of olivine, from the source rock.

The paper provides the first detailed geological description of a portion of the Grampian Highlands between Glen Roy in the west and the Monadhliath Mountains in the east. Moinian metasediments comprising thick granulites (Eilde Flags = Central Highland Psammitic Group) followed by a variable series of pelites and impersistent quartzites (Monadhliath Schists = Transition Group) are succeeded by Dalradian Limestone (Kinlochlaggan or Ballachulish Limestone = Basal Calcareous Group). The Monadhliath Schists are shown to be stratigraphically equivalent to those of Lochaber below the Ballachulish Limestone.

Structurally the area consists of north-easterly anticlines and synclines which are generally isoclinal and often overturned. Many formational junctions are clearly stratigraphical, but the point is discussed whether tectonic contacts (slides) may also be present. Most of the metasediments are of garnet grade, but in the east there is a poorly-developed kyanite zone, and a well-developed sillimanite zone. The high-grade zones are related to a major migmatite and pegmatite belt (the Strathspey Complex); another pegmatite belt occurs farther west around Loch Laggan. Post-tectonic granite, quartz-diorite, diorite and appinite intrusions are also present. The district is traversed by several important north-easterly faults which are later than both the metasediments and the intrusions.

Arthur's Seat is the remains of a dissected Lower Carboniferous volcano, from which were erupted a series of basaltic rocks representative of the province to which it belongs. The rocks occur as lavas, intrusions and tuffs, and include basalts of Dalmeny, Jedburgh, Dunsapie, Craiglockhart and Markle types, in addition to mugearite. For convenience the basalts of Dunsapie type have been subdivided into Normal and Feldspathic varieties.

The volcano has been remapped; some minor departures from the six-inch Geological Survey map are recorded and certain changes in the numbering and classification of the lavas have been made.

The petrographic characters of the various volcanic rocks are described in detail, with modal and chemical analyses. The composition of the parental magma of the volcano was probably very similar to that of Normal Dunsapie basalt. Markle and Craiglockhart types were produced as complementary differentiates of the parental liquid by a process of gravity differentiation, in which sinking of ferromagnesian crystals, particularly augites, played an important part. The basalts of Dalmeny and Jedburgh types, which in Arthur's Seat have strong chemical resemblances, probably represent only slightly differentiated parental magma. Concentrations of soda-rich volatiles produced intense albitisation in the Markle basalts and the mugearites. It is considered that the mugearites of Arthur's Seat crystallised initially as Jedburgh or Dalmeny types, and were altered to their present state during a deuteric phase.

An attempt has been made to reconstruct the eruptive history of the volcano. The magma source appears to have been replenished with parental magma at least twice during the period of activity. The first and last eruptions were of Dunsapie basalt; the albitised products appeared at a fairly late stage.

One of the writers' main aims has been to help to prepare the way for a new approach to problems in which the natural occurrence of forsteritic olivines is a vital factor. Variation in their shapes and textural relations in minor intrusions, lavas and melts is examined and the historical development of concepts of their growth and resorption, particularly in magmas, is traced. Particular attention is focused on the olivines of picritic, minor intrusions. It is concluded that in the interpretation of olivine shapes there has been discrimination in favour of magmatic resorption rather than skeletal crystallization. From a wide and detailed survey of forsteritic olivines it is established that they tend to grow rapidly and that their phenomenal variation in habit and shape is probably due to a specific growth sensitivity to slight environmental differences. Concepts of the physical conditions leading to skeletal crystallization are briefly reviewed and discussed.

The life history of Petrobius brevistylis Carpenter is described from material reared in the laboratory and captured in the field (south Devonshire). A method of identifying the first eight instars is discussed and their diagnostic morphological characters described. Fecundity and time of oviposition are considered at some length. The effects of climate on various phases of the life history are considered as well as the faunas found associated with P. brevistylis. A brief description of the life history of P. maritimus (Leach) is included.

The scent-producing area of closely packed holocrine and apocrine skin-glands in Aotes has an atypical, caudal position. Whilst most of the holocrine glands open into hair follicles by ordinary short ducts, some of the ducts are elongated, opening either into follicles or on the skin surface. The holocrine and apocrine secretions, in conjunction with the peculiar splitting of individual hairs, cause felting of the pelage on the gland field. A peculiar structure of the hairs facilitates their splitting. Evolution and function of the gland field are discussed.

It is generally believed that in mammals the impulse for cardiac contraction is conveyed from the atria to the ventricles by the atrioventricular bundle and its branches. This belief is mainly based on the A-V. dissociation which is found to follow experimental injury of the bundle. Since the bundle contains nerves, as well as specialized muscular elements, these experiments do not conclusively prove which structures, nerves or muscle, actually conduct the impulse. In the dog it has been previously shown that the right limb of the bundle is not usually accompanied by nerves, and in the present work the attempt was made by means of very small incisions to cut the muscle (Purkinje) fibres of the limb without damaging nerves in the ventricular septum, the effect on the electrocardiogram being noted. In 5 out of 38 perfused hearts of dogs the experiment was successful, and resulted in a significant delay in the contraction of the right ventricle relative to that of the left. The experiments also revealed that very considerable damage can be inflicted on the nerves in the ventricular septum without altering the electrocardiogram, so long as the limb itself is not injured. The results are regarded as providing direct evidence that the cardiac impulse in the dog is transmitted to the right ventricle by the muscular elements of the right limb of the bundle, and it is submitted that there would seem to be no valid reason for supposing that conduction throughout the A-V. bundle and its limbs is other than myogenic.

A Summary is given of the field relations, geographical distribution and petrography of twenty-nine dolerite plugs associated with the Tertiary lava plateau of north-east Ireland. All but two of the plugs are composed of olivine dolerite. The exceptions are a pyroxene-rich dolerite and a tholeiitic type containing abundant chlorophæite. Trace-element determinations have been made on specimens from thirteen of the plugs.

Slight but definite chemical differences are shown to exist between the olivine-dolerites and the average Tertiary olivine-basalt lava of the area. The petrogenetic relationships of the two are briefly considered.

The Leadhills–Wanlockhead mining field is situated within a synclinorial belt of greywackes, bounded to the north and south by anticlinoria in which lower stratigraphical elements are exposed. The universal strike is N.E.–S.W. The southern margin of the northern anticlinorium is delimited by a strike thrust fault, inclined to the north-west. The shear zone caused by this thrust is considered to be the principal structural feature governing the localization of the ore deposits.

The complex N.E.–S.W. folding and faulting, imposed during the Caledonian orogeny, is crossed by a series of intersecting joints, whose average strike is N.N.W. The majority of the mineral veins also trend N.N.W. The formation of these discordant structural features under Caledonian stress is demonstrated by the presence of N.N.W. trending Caledonian dykes.

Sinistral movement along the joint pattern, ascribed to a reorientation of the “Caledonian” stress towards an “Hercynian” direction, resulted in the formation of open spaces on the more north-westerly trending members of the joint system in the greywacke belt. This feature is considered to be the secondary structural control responsible for the localization of the ore deposits.

Fifty-seven minerals were identified from the deposits. Fifteen of these minerals had not been previously recorded from the locality, including (1) a new chromian mineral; (2) a new variety, chromian leadhillite; (3) a mineral previously recorded only as an artificial product, lead hydroxyapatite; (4) phœnicochroite, not previously confirmed in the British Isles.

Two periods of mineralization were distinguished. The first consisted of quartz veins with which are associated small amounts of gold, pyrite and muscovite, tentatively assigned to the Caledonian orogeny, and the second comprised the lead-zinc mineralization. The paragenetic relationships of the primary minerals of the lead-zinc mineralization indicate two generations of sulphides; the second generation is accounted for by reprecipitation of elements derived from the replacement of the first generation by late stage quartz. A study of the distribution of elements through the paragenesis suggests that some elements were derived from other than a magmatic source, and that contamination has probably played a considerable rôle in the control of the character of the gangue minerals.

Evidence that the mineralizing solutions had a deep-seated origin is provided by the mineral zones and the geochemical character of the deposit. Emplacement of the minerals took place at a temperature of the order of 143°−281° C, and a depth of the order of 2000–4000 feet below the surface.

The Leadhills–Wanlockhead deposits are related to other lead-zinc deposits in Britain. On the basis of geochemical assemblage and the relation to igneous activity, it is concluded that the deposits were probably derived from the top of the tholeiitic crustal layer and the base of the granitic crustal layer, and were genetically associated with the Hercynian orogeny.

A Fertile shoot of Protopitys scotica sp. nov. from the Calciferous Sandstone Series of Dunbartonshire provides the first available information about the reproductive structures of Protopitys which most authors have hitherto regarded as probably a Pteridosperm. The evidence, however, suggests that it is a plant with pteridophytic reproduction. The range in size of the spores suggests too that heterospory with two sizes of spores, megaspores and microspores, was in course of evolution. It is proposed that a new group, the Protopityales, be established to include Protopitys.

This study of the mineralogy and metamorphism of the Moine schists approaches the problem through consideration of the chemical composition of the minerals. The principal minerals of the Moine schists are studied individually, thirty-three new analyses of minerals being given, with four of schists. For all but six analyses the trace elements have been determined and are tabulated. Muscovites, biotites and garnets all show variation of composition with increasing metamorphic grade, respectively with decreasing Fe2O3 and SiO2, increasing MgO and Al2O3, and decreasing CaO plus increasing MgO, these being only the principal variations. The crystal chemistry of the muscovites, biotites and garnets is briefly discussed. Some new data are presented for the relationship of plagioclase and epidote, a relationship which can only be used with extreme caution to indicate metamorphic grade. A dependence of the incidence of a sutured quartz aggregate in psammitic schists upon the microcline content is noted, and it is suggested that the incidence of the breakdown of quartz under the combined effect of temperature (the dominant cause), stress and potassio solutions, all active in the core, is responsible for the production of the core-envelope boundary. This boundary transgresses the strike; within it retrogressive changes have converted Garnet-zone schists to Biotite-zone schists, but outside it the only retrogressive change is garnet to chlorite. The retrogressive metamorphism formed a distinct episode separated from the initial regional metamorphism by an unknown time-interval; during the second metamorphism isotherms were concentric with the dome, declining outwards. The evidence of an epidiorite from the west coast of Morar suggests that during the first metamorphism the zonal state there was that of the Dalradian Biotite-zone; “almandine” garnets in the adjacent schists are extremely rich in CaO and are in equilibrium with microcline.

Details of the anatomy of the heart and the great vessels are recorded in the following genera of prosimian Primates, Loris, Arctocebus, Perodicticus, Galago, Galagoides, Hapalemur, Lemur, Lepilemur and Propithecus, and comparison made with previously published data on Nycticebus. Special attention is drawn to the proportions, shape and mode of branching of the systemic aorta, which is of typical lemurine pattern in all but Loris and Propithecus. In the heart, attention is paid particularly to the valvular arrangements in the right atrium, where much variation has been found; to the number of pulmonary veins entering the left atrium, also a variable feature; to the internal and external morphology of the ventricles and the valvular arrangements therein. The presence of an os cordis is recorded for the first time in any Primate (viz. in Loris), and the occurrence is mentioned of “brown” (glandular) fat sub-epicardially in Loris. The significance is discussed of the principal anatomical features.

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.

An attempt has been made to determine the identity of two desmids commonly recorded from the plankton of British lakes, Staurastrum paradoxum and S. gracile. The original descriptions of these species were clearly inadequate and many subsequent investigators have given their own interpretation as to their identity, so that from the British plankton alone at least six well-defined taxa have been referred to as S. paradoxum and four as S. gracile. Owing to this confusion, and in the absence of type material, it is suggested that the species S. paradoxum cannot be maintained. On the other hand, type material of S. gracile exists in the British Museum and has been re-examined. The principal characters of this species are described and figured and a list of synonyms given. In addition, those Staurastrum species and varieties frequently misnamed paradoxum or gracile, have been described in detail.

This paper provides a comprehensive account of the small spore assemblages of coals in the Limestone Coal Group and Upper Limestone Group (Namurian) of the Lower Carboniferous of Scotland. The coals were obtained from boreholes sunk in the Lothians, Central, and West Fife coalfields. Over ninety species of small spores are figured. Of this number twenty-six are new species. Five new genera—Glomospora, Procoronaspora, Callisporites, Tholisporites and Remysporites—are described. Full descriptions are given of all new genera and species. The assemblages are compared with assemblages of similar age in North America, the U.S.S.R. and elsewhere, and it is shown that the Carboniferous pre-Westphalian microfloras were uniform over wide areas of the earth's surface.

An analysis of the structural style of the Palæozoic rocks exposed around Girvan in S.W. Ayrshire suggests that it was fashioned by at least nine phases of deformation. Five of these phases were active when maximum pressures were horizontal and together constitute the local expression of the Caledonian orogeny. The oldest phase recognized, the Main fold phase, consisted of overfolding due to an over-riding maximum pressure from between 150° and 170° and was penecontemporaneous with thrusting generated by a modal maximum stress from 145° to 325°. Three important thrust belts resulted but there were considerable local swings in the azimuths of maximum stress, a variation which culminated in the propagation of the Ardwell fold and reverse fault phase by a maximum stress from 110°. Later Caledonian movements, presumably influenced by an increase in overburden due to folding and thrusting, were represented by two episodes of wrench faulting: an older Ardwell “cross-fold” phase due to a maximum stress from north-east to south-west and a younger Main wrench system with a maximum stress aligned at 160–340° which generated an intricate pattern of sinistral and dextral shears together with second-order relatives. The three following phases, the first, second and third “normal” phases represented an episode in stress history when the relief of pressure was horizontal and aligned from approximately north to south, north-north-west to south-south-east and just north of west to south of east respectively. Maximum pressures tended to vacillate between the vertical and near horizontal and as a result much of the faulting was oblique-slip. All three phases were responsible for important faults and some evidence is put forward to suggest that all three are possibly Proto-Armorican or probably not later than Armorican, although the existence of a few mineral veins shows that reactivation certainly took place in Borcovician times. An analysis of the tensional joints recorded for the area indicates that, apart from the dominant Caledonian and less conspicuous Armorican sets, Tertiary joints were formed when there was a relief of pressure from north-east to south-west and this final phase of deformation was accompanied by the intrusion of dykes.

The study also includes discussions on the methods and merits of the resolution by stereographic means of the stress fields responsible for oblique-slip faults and on the nature and origin of first- and second-order wrench faulting in the light of the abundant statistical data available.