Jahns and Burnham (1969) proposed that the internal evolution of zoned granitic pegmatites could be explained by crystallisation from water-saturated melts which evolved to produce systems with a melt plus a separate aqueous fluid. Examination of microthermometric properties, chemical compositions and gas contents of solid-liquid-vapour inclusions from a number of the zones of the Tanco rare element granitic pegmatite places constraints on fluid evolution within the framework of the crystallisation history of the pegmatite, and contributes to an examination of the Jahns–Burnham proposal.

Initial crystallisation at Tanco was from the wall rock inwards, producing the relatively unfractionated wall zone (potassium feldspar–quartz-albite-muscovite). Textural evidence, and an upward increase in the level of geochemical fractionation, indicate that much, but not all, of the subsequent crystallisation of the pegmatite was from the base upwards. Inclusions trapped by wall zone and metasomatic wall rock tourmaline indicate that the pegmatite was intruded as a 2 phase alumino-silicate melt/fluid mixture at ∼720°C, with an initial fluid composition of ∼98mol.% H2O (containing 2 equiv. mo1% NaCl) and <2mol% CO2 (containing <5 equiv. mo1% CH4). These observations indicate that both melt and fluid were present from the start of crystallisation (Jahns & Burnham 1969), but show that CO2 and dissolved salts were important additional components of the fluid phase. The bulk of the pegmatite then crystallised in the range 600-470°C from melts and fluids with continued low levels of CO2 (2-3mol.%) and approximately constant salinity (∼7 equiv. wt.% NaCl dissolved in the aqueous phase). Crystal-rich inclusions, which may represent trapped alumino-silicate melts, are present throughout pegmatite crystallisation down to temperatures as low as ∼262°C. The final stages of crystallisation resulted in the formation of the beryl fringe at 291 ± 33°C and the lower part of the quartz zone at 262 ± 29°C. By the later stages the fluid had cooled through an H2O-CO2– dissolved salt solvus resulting in H2O-CO2 phase separation. Gas chromatographic analysis of the fluid components in the vug quartz, beryl fringe and lower part of the quartz zone shows that the inclusions contain H2O, CO2, CH4, N2, CO, Ar, and trace C2H6 in the beryl fringe. Measured CH4:CO2 ratios of 0·0060 (±0·0015) for the beryl fringe (twenty crushes on five samples) and 0·0042 (±0.0021) for the quartz zone (thirty crushes on six samples) yield fO2 estimates of 1×10−36 and 2 × 10−38, respectively, which are just above QFM at these temperatures.

Four new petrified specimens of cupules assigned to Hydrasperma cf. tenuis Long are described from the Cementstone Group of Oxroad Bay, East Lothian. In one of these specimens four ovules are present. Three of the specimens are interpreted as representing a pair of cupules derived from a single megasporophyll showing dichotomy so that each cupule is termed a hemi-cupule and has two lobed halves which represent quarters of the entire megasporophyll. In the fourth specimen five cupules are present, each possessing two lobed halves not sub-divided into quarters. Hydrasperma is thus interpreted as showing two kinds of cupules designated mega-cupules and paired hemi-cupules. The theory is developed that angiosperm carpels have evolved from the two kinds of pteridosperm cupules.

Structures in and around volcanic necks at Dunbar are interpreted as belonging to two different stages in volcanism. Some, which are related to an early neck emplacement stage, include small ring structures—probably incipient (crypto-volcanic) necks—filled with marginally flow-banded breccias, dykes of similarly margined unbedded tuff, and tuff-penetrated wall rocks. Among the last are sandstones veined along planes of minor fracture by very fine sand.

Other structures belong to a later stage during which bedded tuffs, that had originally accumulated sub-ærially, subsided into the necks in a process here likened to caldera formation. In one large neck the bedding is relatively undisturbed, but in smaller necks there are high inward dips from the margins and collapse structures, sometimes accompanied by reconstitution of the clastics, at the centres. Diagnostic features of subsidence margins are anastomozing veins of carbonate, locally accompanied by hæmatite, and these appear to be related to dykes of flow-banded sandstone and sandy tuff intruded along fractures initiated inside the necks during subsidence. Other structures described are ring-fracture, with or without gouge, and down-drag of wall-rocks: these suggest a solution to the space problem posed by caldera mechanism.

Fifteen specimens of Eristophyton stems from the Lower Carboniferous Cementstone Group of Berwickshire and East Lothian have been examined. Three possess medullary rays comparable to E. waltonii Lacey, the others have rays like E. beinertianum (Göpp.) Zalessky. In one specimen assigned to E. waltonii a leaf-trace subdivides outside the secondary xylem to form an arc of six separate bundles. Another stem of E. waltonii has attached closely spaced petiole bases one of which is clearly identifiable as Lyginorachis with six vascular bundles arranged in an arc. Stems of Eristophyton from five localities occur associated with petioles or rachises possessing a U-shaped vascular bundle with abaxial ridges like L. waltonii Calder. As these may occur mixed with rachises agreeing with L. brownii Calder the latter is regarded as synonymous. Detached petioles found associated with E. beinertianum may possess four or six basal bundles. The evidence suggests that the U-shaped petiolar bundle passes down into four then six basal bundles and such petioles are associated with both E. waltonii and E. beinertianum. Calder (1935, pl. 1, fig. 2) showed dichotomy in the petiole bundle.

In addition different rachises are known possessing a more massive U-shaped bundle but lacking sclerotic nests and sparganum outer cortex. These are assigned to Cladoxylon edromense sp. nov. Cortical nests occur in both E. waltonii and L. waltonii and may be compared with the sclerotic plates in the compressions of Diplotmema dissectum Brongn. and D. patentissimum Ett.. The evidence supports the view that Eristophyton is a pteridosperm with bifurcate fronds known as L. waltonii Calder when petrified and comparable to Diplotmema when compressed.

Most granites result from partial melting within the crust. Granite melts produced at the lowest temperatures of partial melting mainly comprise close to equal amounts of the haplogranite components Qz, Ab and Or, with H2O. Many felsic granites were formed by partial melting under such conditions and are low-temperature types, with crystals of zircon and other restite minerals present in the initial magma. Such magmas evolve in composition, at least initially, through fractionation of that restite. If one of the four haplogranite components either becomes depleted or too low in amount to contribute further to the melt, then melting may proceed to higher temperatures without a contribution from that component. Melting will advance to significantly higher temperatures if there is a critical deficiency in one or more components and a high-temperature granite magma forms, in which zircon is completely soluble. Such magmas are extracted from the source in a completely molten state and may evolve by fractional crystallisation. They are monzonitic, tonalitic or A-type, depending on whether the critical deficiency occurred in the Qz, Or or H2O component. If the Ab component is critically deficient, as in pelitic rocks, the rocks may be infertile for granite production. The control that source rock compositions exert on both the physical and chemical properties of granite magmas provides a unifying element in granite gen

One of the rarest tetrapods in the East Kirkton fauna is an aïstopod represented by very fragmentary material of five individuals. It is described as a new species of the genus Ophiderpeton which is redefined and restricted to broad-snouted forms with large, robust teeth from the late Viséan and early Westphalian. Later Westphalian species are referred to the genus Oestocephalus.

A new genus and species of primitive echinozoan, Bromidechinus rimaporus, is described from the Upper Ordovician of Oklahoma, USA. This has a unique plate arrangement. There is a single perradial series of imperforate plates bounded on either side by a column of perforate ambulacral plates. A double column of interambulacral plates separates ambulacral zones. The sparse record of Ordovician echinozoans is reviewed and cladistic analysis suggests that Bromidechinus represents a lineage that diverged prior to the split between bothriocidarids and main-line echinoids. This leads to a revised interpretation of the earliest stages of morphological evolution of echinoids.

Isotope ratios of elements such as Sr, Nd, Pb and Hf can be used as tracers of magmatic sources and processes. Analytical capabilities have evolved so that isotope ratios can now be analysed in situ, and isotopic tracers can therefore be used within single minerals to track the changing magmatic environment in which a given mineral grew. This contribution shows that Sr isotope ratios in feldspars that make up plutonic rocks will typically preserve initial isotopic variations, provided precise and accurate age corrections can be applied. Variations in initial isotope ratio can give a core-to-rim record of magmatic evolution and can be used to diagnose open system events such as contamination and magma recharge and mixing.

New single grain Sr isotope data are presented from the Dais Intrusion, Antarctica, which reflect an open system origin for the crystals. The crystal cargo appears to be aggregated and assembled during transport and emplacement. This model, as opposed to a magma body crystallising post emplacement, may be more applicable to plutonic rocks in general, and is testable using the in situ isotopic determination methods described here.

The fossils which form the subject of this paper were collected in the summers of 1933 and 1934 by my son and myself at Earnstrey Hall Farm on the western slopes of Brown Clee in Shropshire. I had become interested in specimens collected at this locality by Mr W. Wickham King, M.Sc, which Sir Arthur Smith Woodward (1934, p. 566) named Corvaspis, and it was with the intention of obtaining further material of this genus that I got King to tell me exactly where he had found the best of his specimens. The section is in a small stream course 570 yards north 11° east of the farm and at the bottom of the escarpment formed by the “Psammosteus Limestone” and in the beds assigned to Zone I, 8 of King's classification (King, 1925). At the particular spot in question there is (in normal years) a waterfall over a 4-foot band of very tough calcareous pellet rock and conglomerate with occasional quartz pebbles up to about 1 inch diameter. This, especially its lowest few inches, had yielded the specimens that King had found, and from it we also collected abundant fragments of Corvaspis. Nearly all the specimens of Phialaspis (p. 439) which we discovered came from this rock, as did a fine example given by King to the British Museum and referred to later (p. 440). In 1934 the same rock yielded cf. Ctenaspis. Below this rock there is about 18 inches of grey shale, in which King had noted black streaks. This rests on several feet of red clay.

In order to understand the governing factors of petrological features of erupted magmas of island-arc or continental volcanoes, thermal fluctuations of subvolcanic silicic magma chambers caused by intermittent basalt replenishments are investigated from the theoretical viewpoint. When basaltic magmas are repeatedly emplaced into continental crust, a long-lived silicic magma chamber may form. A silicic magma chamber within surrounding crust is composed of crystal-melt mixtures with variable melt fractions. We define the region which behaves as a liquid in a mechanical sense (‘liquid part’) and the region which is in the critical state between liquid and solid states (‘mush’) collectively as a magma chamber in this study. Such a magma chamber is surrounded by partially molten solid with lower melt fractions. Erupted magmas are considered to be derived from the liquid part. The size of a silicic magma chamber is determined by the long-term balance between heat supply from basalt and heat loss by conduction, while the temperature and the volume of the liquid part fluctuate in response to individual basalt inputs. Thermal evolution of a silicic magma chamber after each basalt input is divided into two stages. In the first stage, the liquid part rapidly propagates within the magma chamber by melting the silicic mush, and its temperature rises above and decays back to the effective fusion temperature of the crystal-melt mixture on a short timescale. In some cases the liquid part no longer exists. In the second stage, the liquid part ceases to propagate and cools slowly by heat conduction on a much longer timescale. The petrological features of the liquid part, such as the amount of unmelted preexisting crystals, depend on the intensity of individual pulses of the basalt heat source and the degree of fractionation during the first stage, as well as the bulk composition of the silicic magma.

The Carboniferous trilobite Paladin eichwaldi shunnerensis (King 1914), at its type locality in northern England is exceptionally well-preserved, and shows all stages of growth from the degree 0 meraspis onwards. The post-protaspid ontogenyis described here with particular reference to the development of cuticular sculpture. On the dorsal surface of the smallest specimens a polygonal network of raised ridges (cell polygons) is apparent. With size increase, granules progressively appear amongst the polygons, which in turn change into large tubercles as the polygonal network fades. As the trilobite grows into an adult, the tubercles become relatively smaller, and pits, the openings of cuticular canals, appear amongst them. Marginal terrace lines become pronounced. On the hypostome, however, terrace lines become effaced centrally, while large pits develop. In the early meraspis the eyes are “schizochroal”, but the lenses rapidly become closely packed and contiguous and the eye is soon of “holochroal” type. The meraspid phase is passed through very rapidly. Whereas the earlymeraspis could not enroll, its pygidium could be bent down vertically, and this facility might have allowed the larva an escape reaction.

It is confirmed that the type species of the genus Glyptoscorpius Peach 1882 is a subjective synonym of Adelophthalmus Jordan and Meyer 1854. Species which have been referred to Glyptoscorpius are reviewed and their present taxonomic position defined. Cyrtoctenus gen. nov., type species Cyrtoctenus peachi sp. nov., is designated to accommodate forms bearing five pairs of specialised abdominal appendages of which the first is comb-like. Four species of Cyrtoctenus from Devonian and Carboniferous rocks in Scotland, England, Belgium and Czechoslovakia are recognized. The structure and affinities of these forms are discussed with special reference to the comb-like appendages and their ornamentation in relation to these features in other arthropods. In particular the development of filaments and fulcra from different types of scales is discussed. The characters of the new genus are found to be so distinctive as to require the creation of the new order Cyrtoctenida for its accommodation.

During the last few years Dr R. Kidston, F.R.S., has kindly entrusted to me for investigation certain specimens of fossil plants, showing structure, mostly from Lower Carboniferous horizons in Southern Scotland.

Four of these plants are dealt with in the present communication, namely:

Calamopitys radiata, sp. nov.

Calamopitys zonata Kidston, in MS. (now Endoxylon zonatum).

Bilignea solida Kidston.

Bilignea resinosa, sp. nov.

It will be understood that all the specimens were in Dr Kidston's hands in the first instance; the sections were cut under his direction, and he himself had determined the chief points in the structure of each before I began my observations. It only remained for me to work out the details, and to form my own views as to the probable affinities of the plants.

There have now been described some fourteen hundred species of Tabanidæ, of which, according to Surcouf (1924), more than a hundred are European. Biological studies of the family have by no means kept pace with those of its taxonomy, and there is available comparatively little information regarding the post-embryonic development of individual species.

Examination of the literature showed that none of the European species had been investigated with any degree of detail, and it was with the intention of supplying at least part of this want that the present study was undertaken in 1930. Because of its relative abundance from June to August in rural districts of Scotland, the common cleg, Hœmatopota pluvialis, L., was the species first chosen. The interest of this choice was considerably increased by the relisation that the biology of no species of Hœmatopota had previously been submitted to careful examination either in Europe or elsewhere.

In the early part of the present century, when stratigraphical geology, starting from the clear succession of Secondary rocks of England, was groping its way among the older formations in this country and abroad, the Old Red Sandstone occupied a somewhat indeterminate position. The series of deposits comprised under that name had been recognised chiefly in the British Islands, hardly at all on the opposite mainland of Europe. By most geologists they were classed as a subordinate and inconstant portion of the Carboniferous system, while by some they were placed rather at the top of the yet unexplored “Transition” or “Greywacke “ series. Murchison first claimed for them the dignity and importance of a distinct system. On the whole, they had yielded comparatively few organic remains; they consequently seemed to lie as a thick red barren zone between the richly fossiliferous Silurian deposits below them and the equally fossiliferous Carboniferous limestone above. By degrees, however, as they brought forth a rich harvest of new and strange ichthyolites, they indicated their own right to recognition, and when they were found covering a vast space in Russia with many of the same types of fish as they had yielded in Britain, their claim to rank as a distinct and independent system was no longer contested.

The fossil ricinuleids are described, and their systematic relationships revised, based on a study of all British and American specimens. Phylogenetic analysis, utilising a new character set, indicates a probable basal dichotomy between the fossil and extant forms. The order is divided into two new suborders: Neoricinulei subordo, nov., for the extant genera, and Palaeoricinulei subordo. nov., for the fossil forms. Two new genera are erected: Amarixys gen. nov. for Curculioides gracilis (Petrunkevitch, 1945) and A. stellaris sp. nov., and Terpsicroton gen. nov. for Poliochera alticeps Pocock, 1911. Three new species are erected in the genus Curculioides: C. mcluckiei sp. nov., C. pococki sp. nov., and C. gigas sp. nov., and one in the genus Poliochera: P. gibbsi, sp. nov.

In late Ordovician and early Silurian times, the Girvan district lay in a shelf marinesetting on the margin of Laurentia, on the northern side of the Iapetus Ocean. The Lower Palaeozoic rocks of the Girvan district, and their shelly and graptolitic fossil fauna, were systematically described by Lapworth in 1882 and have formed an important research resource ever since. They provide valuable evidence for the depositional environment and geological setting of Girvan during the early Palaeozoic, in both regional and wider contexts, and demonstrate the long-recognised close affinity with contemporaneous Laurentian faunas. However, by late Ordovician and into Silurian times, the earlier Iapetus oceanic barrier to faunal migration had largely gone and there is good correlation between contemporaneous marine fauna throughout the British Isles and Scandinavia. Despite much recent research in the area, including resurvey work by the British Geological Survey, no comprehensive review of Silurian lithostratigraphy at Girvan has been published since the revision by Cocks and Toghill in 1973. The present review of the Silurian rocks addresses this need and complements the recently published (Fortey et al. 2000) revision of the underlying Ordovician rocks, thus bringing the entire Girvan Lower Palaeozoic succession up to modern standards of nomenclature.

The breeding habits of this asterid have been noted by M. Sars, who has described the external features of the developmental stages. He observed the peculiar habit of ‘brooding.’ In the spring of 1840 he found several of the parents at very low-tide-mark fixed to stones in their brooding position. The species he examined is described as Echinaster sanguinolentus, and is apparently the same species, though he speaks of the ‘blood-red’ embryo, whereas my specimens were a light orange. They conform exactly to the tint of the oral surface of the parent. The time of breeding of Cribrella oculata at St Andrews appears to extend from February to April inclusive, and throughout this period the parents are found fairly plentifully, adhering to the under surface of rocks, nursing the masses of eggs or young under their bodies. This habit of protecting its young is also pursued by an allied species, Asterias mütteri, which is equally abundant in the same locality, but the breeding of which is effected earlier, i.e., in November and December. I hope to proceed with the study of this species in the near future.

The first whipspider (Arachnida: Amblypygi) and three new examples of whipscorpions (Arachnida: Uropygi: Thelyphonida) are described from Lower Cretaceous (Aptian) strata of the Crato Formation, Ceará State, Brazil. The whipspider is described as Britopygus weygoldti gen. et sp. nov. It resembles members of the extant family Charinidae, but cannot be unequivocally placed. Two of the whipscorpions are referred to Mesoproctus rowlandi Dunlop, 1998 and one could be a subadult, since, like juveniles of extant species, it has a relatively broad anterior sternum. There are differences between these two specimens in pedipalp and flagellum morphology, but both characters are variable within extant species. The third and largest whipscorpion is incomplete and referred to Mesoproctus sp. Its carapace length is equal to or exceeds that of the largest known extant genus Mastigoproctus Pocock, 1894.

Material excavated from a trench dug to expose the Rhynie Cherts Unit of the Dryden Flags Formation included blocks of Rhynie chert up to 50 cm thick and comprising the full thickness of plant-bearing chert beds. These blocks, and others collected as float, display a variety of macro-textures typical of silicification at the terrestrial surface and in shallow water. On sandy terrestrial surfaces, autochthonous and allochthonous plant debris and plant rhizomes are well preserved, but aerial axes generally decayed prior to silicification. In shallow water, clonal plants, particularly Rhynia, are preserved with aerial axes in growth position, supported by microbial mats and meshworks. Preservation of such delicate fabrics required the creation of a load-bearing framework early in the silicification process, to prevent crushing during early burial.

On the microscale, plant taphonomy reveals characteristic features due to plant decay prior to silicification in both wet and dry conditions, and also during the silicification process. Silicification of plants was frequently very rapid, preserving delicate transient features such as spore germination and ejection of sperm cells from antheridia. In situations where plant tissue continued to decay during silicification, the process was slower.