A study of Stephanocerataceae and Perisphinctaceae of the Middle Jurassic demonstrates that the structure of the septa comprises a complex vault and pillar system which is functionally adapted to the dimensions of the tube so as to give maximal stability to the shell. Only through a study of the septum can we interpret the different forms of the suture and discriminate between important and unimportant features. Different septa may have analogous sutures, especially in the external parts. These septal patterns are strikingly consistent within subfamilies or families even where other features suggest overlap between the groups. Some parts of the septum are not adapted, but either retained from earlier ontogeny or inherited, and constitute vestigial (genotypic) characters distributed through taxons.

These empirical results have been applied to the taxonomy of some groups of hitherto doubtful systematic position (Cadomitinae, Normannitinae, Sphaeroceratinae, Parkinsoniidae, Spiroceratidae).

The paper contains eight analyses of primary and recrystallized pyroxenes from the layered ultramafic peridotite at Dawros. The assemblages in which these pyroxenes occur are compared to those from other peridotites and some comments are made on the pyroxene sequence. Consideration is also given to the problems arising as the result of the metamorphism of the primary igneous accumulate at Dawros.

An account is given of the petrography and chemistry of the bostonite of Rudh'a' Chromain, Mull.

Carboniferous and Permian fossils collected from Central Vestspitsbergen between 1938 and 1957 are listed according to formations and the age of each is assessed from these determinations. Resting unconformably on folded Devonian or metamorphosed Hecla Hoek the succession begins with plant-bearing continental facies and passes upwards into a marine succession with fusuline, coral and brachiopod faunas in limestones and dolomites associated with evaporites and cherts. Correlation with rocks elsewhere in Svalbard, which has been effected largely by lithological facies, is reassessed on palaeontological evidence; this consists of a sequence of plants from approximately Tournaisian to Namurian; of fusulines from the Fusulina Zone to the Pseudoschwagerina Zone, with the Carboniferous-Permian boundary falling in the middle of the Wordiekammen Limestones; and of brachiopods above this. The youngest fossils may be Upper Permian. The succession has few breaks and with further study will contribute to the correlation of Russian, West European, Greenland, and American rocks.

Spore nomenclature and palaeobotanical nomenclature follow exactly the same rules. In both there are difficulties which must be understood historically.

The paper describes minor fold structures, from the Dalradian of Scotland and Donegal which, following their formation, appear to have suffered partial rotation. These folds lie with their axial directions at an angle to the regional fold pattern.