The petrography of the greywackes is described, with special emphasis on rock and mineral grains indicative of provenance. Sedimentary structures are discussed, and current directions based on flute cast measurements are recorded. The stratigraphy and palaeontology of the Denbigh Grits, and the facies of other parts of the Wenlock in the Welsh area are also considered. It is concluded that the greywackes were derived from an area of Pre-Cambrian rocks near south-west Wales and that they were transported along the axes of subsiding troughs by turbidity currents.

Remapping of parts of the Galway granite has shown that over most of its outcrop it is a homogeneous adamellite. A steeply dipping belt of basic rocks borders the intrusion on the north where there is a reaction zone between adamellite and basic rock. A similar but gently dipping belt of basic rocks overlies the granite to the west. In the south, where there is no reaction zone, the granite intrudes and hornfelses a group of pillow lavas, greywackes, and conglomerates. The structural features of the northern border indicate that the granite has been emplaced as a diapir and radial fractures in the north-east border further indicate that the granite and its basic envelope moved upward and outward together into the Connemara schists.

In the later growth stages of Palaeosmilia, minor septa are inserted simultaneously on both sides of each newly added major septum and they originate high up near the growing crest of this major septum. Thus, a minor septum occupies the interseptal space in which the next major septum will be inserted. The next major septum develops directly upon the axial edge of this minor septum and it originates deep down in the calyx. The similarity is pointed out between the septal insertion in Palaeosmilia and in the more typical aulophyllid (clisiophyllid) corals.

Antidune wavecrests preserved in mud by contemporaneous currents carrying silt are discussed with reference to some recent criticism. In turbidity currents, at slow rates of directional flow, turbulent eddies may be operative in keeping sediment in suspension. Torose structures and flow marks from the Gala-Tarannon of Southern Scotland are compared with structures probably eroded by turbulent currents in the Gronigel Flysch of the Pre-Alps.

The form and distribution of load-casts suggests a genetic connection with structures previously formed on the upper surface of the underlying bed. On analogy with salt-dome development, the growth of load-casts and associated flame-structures is attributed to the density contrast between upper and lower bands and differential loading caused by the projections and depressions formed by the upper-surface features. This hypothesis is the basis of a new classification of load-cast structures.

Growth of the glabella of the trilobite Dalmanitina olini is studied by plotting various dimensions y against the length of the glabellar stalk x which is taken to represent absolute size. The relations are fitted best by linear equations y = a(x + b/a), and for several dimensions the value of b/a appears to be constant. The concepts of absolute and specific growth-rates are discussed in relation to the glabella of D. olini.

The quartz-syenite outcrop in the Las Anod District of the Somaliland Protectorate has been known for at least twenty-three years, but the true relationship between it and the overlying Cretaceous sediments has not been clearly resolved. Some geologists have said that the igneous rocks are overlain unconformably by the Cretaceous, whilst others have said that they intrude the Cretaceous. The present contribution brings forward field evidence to confirm the former view.

Graptolites, found in Ordovician strata in a deep boring in northern Syria, are described as Diplograptus spinulosus Sudbury sp. nov.

Six species (one new) of holothurian sclerites, representing the genera Achistrum, Rhabdotites, and Etheridgella, from the Upper Bathonian of the Dorset coast are figured and described, and are the first of such organisms to be recorded from the Great Oolite of England.