Past work on the genus Pitus is reviewed and evidence adduced in favour of the view that it was a genus of arborescent Pteridosperms bearing the sterile bifurcate fronds known as Lyginorachis papilio Kidston. These probably resembled Sphenopteris affinis L. & H. in the compression state. Fertile organs were probably borne on trifurcate fronds in which a stemlike median rachis (Tristichia ovensi Long) bore synangia (Telangium sp.) composed of eight microsporangia, or alternatively seed-cupules of Stamnostoma huttonense Long. Branching in Pitus produced single branches at a wide angle, or pseudo-whorls (close spirals) of about five branches. An anomalous ring of medullary xylem was sometimes associated with branching as in Lyginopteris. This supports the view that Pitus should be classified in the Lyginopteridaceae although it was arborescent and in some respects more advanced than many of the more shrub-like Pteridosperms.

Six new specimens of petrified cupules of Hydrasperma cf. tenuis from Oxroad Bay, East Lothian (Cementstone Group) have been examined. Sections of one show a close similarity in size and shape to compressed cupules of Sphenopteris bifida L. and H. from the Lewis Burn (Scremerston Coal Group or lower Viséan) of Northumberland. The conclusion reached is that cupules of Hydrasperma cf. tenuis Long are petrified equivalents of the compressed cupules of Sphenopteris bifida L. and H. The morphological significance of this identification is discussed.

The limpet Acmaea virginea is an important agent of erosion of bivalve shells within the photic zone. This lower limit is governed by the depth range of shell-boring algae on which it feeds, the dominant alga being conchocelis. Any authigenic ferromanganese coatings on shells are removed by the grazing and the shells may become wafer thin and highly fragmented. The chiton Lepidopleurus also grazes shell surfaces but feeds more on superficial detritus than on the boring algae, and so its depth range is not so restricted. Both molluscs leave highly distinctive radula marks on shells which are potentially preservable in the fossil record. Acmaea virginea produces broad scoops, six-pronged, with very sharp narrow interstitial ridges. Lepidopleurus produces short, sharp scratches in sets of two, three or four, with wide interstitial ungrazed plateaux.

The faecal pellets of both species contain 5–10 μm sized carbonate particles. Whereas there is little else in Acmaea pellets, which are white, cylindrical and only loosely held together, chiton pellets include much fine manganiferous material, detrital quartz and broken diatom frustules, and are well bound with mucilage which makes them dirty brown-grey in colour and ovoid. The data indicate that physical processes need no longer be assumed to be the major factor in the recycling of carbonate from shells, and in their fragmentation.

The term ‘monchiquite’ has suffered such conflicting usage that a redefinition is here proposed: monchiquites are alkaline lamprophyres with essential brown amphibole and/or biotite but not necessarily with olivine, possessing a near-isotropic feldspar-free base of glass (hyalomonchiquites), analcime (analcime-monchiquites) or nepheline (nepheline-monchiquites). This effectively reverts to Rosenbusch's original definition, whilst accommodating established practices in the subsequent literature. Notwithstanding certain published interpretations, the type monchiquites from Monchique and Rio de Janeiro are hyalomonchiquites.

The Monchique monchiquites are associated with camptonites and sannaites in a dyke swarm invading the Monchique foyaitic intrusion. Field, petrological, geothermometric and geochemical evidence is presented to suggest that these dykes resulted from two mixing processes: (i) a version of Bowen's classic reaction between mafic crystals and alkaline liquids—here between cumulus divines and foyaitic magma; (ii) hybridisation of hydrous theralitic and nepheline syenite magmas, restricted by liquid immiscibility. The secondary origin of certain dykes is evinced by extreme mineralogical disequilibrium. The monchiquites could represent a more advanced stage of such processes than the camptonites and sannaites.

A method of conducting a resistivity sounding, up to a maximum spacing of 5 kilometres, is described. By conducting measurements, in a symmetrical fashion, about the sounding centre and in two perpendicular directions, it is possible to obtain results which are relatively insensitive to the orientation of the electrode array used and entirely related to the local area around the sounding centre. By choice of the progression of spacing used, it is also possible to express the results in terms of resistivity measures suitable for subsequent interpretation.

A resistivity sounding curve, conducted in this manner at Rookhope, shows the existence a highly resistive basement at interpreted depths which are in reasonable accord with the known depth to the Weardale granite in this area.