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The question of buoyancy control of ammonoids in relation to the function of the siphuncle is analysed in the light of flotational experiments on exact models of moderately evolute and highly evofute shell types, and the structure of the siphuncle. It is demonstrated that, if the mode of life of the ammonoid animal were analogous to that of living Nautilus, the relatively more buoyant shell of most ammonoids would have needed considerably more liquid in its chambers than Nautilus, with many of the chambers completely filled.

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Labyrinthidoma dumptonensis gen. et sp. nov., belonging to the Superfamily Lituolacea, is described from the Chalk of southern England. It has a distinctive mode of growth, chambers with labyrinthic interiors, and cannot be fitted into any of the existing families of the Lituolacea as presently denned.

• Read more about An unusual agglutinating foraminifer from the Upper Cretaceous of England

Isotopic methods of assessing Wealden palaeoenvironments are reviewed. Emphasis is placed on the importance of using only primary, skeletal, untransported carbonates. Recrystallization and cementation generally reduce the 13C/12C and 18O/16O ratios of Wealden carbonates. Hence, while those with high 13C/12C are likely to be marine, those with low 13C/12C cannot be assigned to a depositional environment unless known to be primary.Ratios from aragonitic shells of one species each of Cassiope, Neomiodon, and Filosina? indicate 'marine' conditions.

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Certain gastropods from the Pierre Blanche de Langrune (Upper Bathonian) at Lion-sur-Mer, Calvados, France, have been encrusted by a succession of ectoproct zoaria. After the death of the gastropods, the vacated shells, with their encrustations, have been occupied by hermit crabs. Abrasion of the shell during locomotion of the crabs produces flat areas near the shell aperture, and discontinuities in the ectoproct colony growth. The relationship between the ectoproct and the inhabitant of the shell is considered to be one of true symbiosis.

• Read more about Symbiotic relationships between ectoprocts and gastropods, and ectoprocts and hermit crabs in the French Jurassic

Using the Cicatricosisporites group of palynomorphs, events raised from ten selected samples from the 'Wealden' of Worbarrow Bay, Dorset, are bracket-correlated with events of similar nature from the Warlingham Borehole, Surrey. Although sedimentation rates appear to have differed, deposition at Worbarrow seems to have continued throughout much of Berriasian to Aptian time as at Warlingham. The constituent data of the events comprised graded comparison records with the use of twelve new biorecords and some of those published by Hughes and Moody-Stuart (1969).

• Read more about Palynologic correlation of the Dorset 'Wealden'

Chuaria circularis from the late Precambrian of the Grand Canyon was regarded by Walcott as a primitive brachiopod. It has subsequently been referred to as an alga, a chitinous foraminiferid, a gastropod, a hyo-lithid operculum, a trilobite egg, and an acritarch. It is here suggested that Chuaria is a compressed, unusually large planktonic organism (generally 2 to 5 mm diameter). Chuaria wimani, Fermoria, and unnamed material from Canada, Sweden, France, Siberia, India, Iran, and Australia show no systematic differences from C. circularis and are considered synonymous.

• Read more about The problematical Precambrian fossil Chuaria

Three species of trilobites from the Clifton Down Limestone (Visean) at Holwell Quarry in the Mendip Hills (Somerset) are described: Linguaphillipsia matthewsi sp. nov., Phillipsia (Phillipsia) holwellensis sp. nov., and Cummingella jonesi jonesi (Portlock 1843). This is the first record of the genus Linguaphillipsia Stubblefield 1948 from the Carboniferous Limestone of western Europe.

• Read more about Viséan trilobites form Holwell, Somerset

Direct study of the course of evolution of bivalve shell structures has been prevented by the lack of well-preserved lower Palaeozoic material. The 'primitive' molluscan shell structure probably consisted of an outer aragonitic prismatic layer, the prisms being polygonal in transverse and columnar in longitudinal sections. The middle and inner shell layers consisted of nacreous structures. Morphologically similar structures are produced inorganically from the solidification of metals containing impurities.

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Thirteen trilobite species are described and illustrated from Upper Ordovician successions of central New South Wales. They include the new species, Remopleurides saenuros, R. exallos, R. acer, Pseudobasilicus? fortis, and Illaenus (Parillaenus)? incertus, and records of Shumardia, Geragnostus?, and a harpid. A discussion of possible dimorphism in Remopleurides is presented.

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In the Mendip Hills, the lower part of the Carboniferous Limestone succession (the Lower Limestone Shale and Black Rock Groups) extends to greater thickness than is found in the Avon Gorge at Bristol. Conodont faunas from this range of the Mendip succession are described here. A distinctive lag-type deposit occurs low in the Lower Limestone Shale Group. Faunas below this lag (with Patrognathus, Pseudopolygnathus dentilineatus, Polygnathus symmetricus) cannot yet be dated precisely.

• Read more about Lower Carboniferous conodont faunas from the eastern Mendips, England