3050 dead molluscan shells and fragments of calcareous algae were collected from 104 benthic stations at depths from 2 to 160 m in the Firth of Clyde, the Firth of Lorne and on the Orkney shelf, British Isles. The following micro-algal borings were recognised and are described: (i) Rhodophyta: Conchocelis, (ii) Chlorophyta: Ostreobium quekettii, Eugomontia sacculata, Phaeophila sp. and (iii) Cyanophyta: Plectonema terebrans, Hyella spp.

These endolithic algae are bathymetrically zoned. Eugomontia, Phaeophila and the cyanophytes characterize the upper part of the photic zone (2–20 m). Shallow sheltered environments are typified by a high density of algal borings, most of them aligned perpendicular to shell surfaces. The lower photic zone is characterized by Ostreobium and Conchocelis whose borings are parallel to shell surfaces. The photic limit is about 40 m for the open Orkney shelf (59°N), and about 22 m for the partly enclosed firths (56°N).

The Orkney population is dominated by two chlorophyte taxa: rhodophytes and cyanophytes are absent. This may be due to higher tidal energy conditions.

Twenty-seven species assigned to 20 genera of trilobites are described from Feilaishi in Guizhou Province, the type section of the Shihtzupu Formation in S W China. They occur in association with a sparse graptolite fauna including Glyptograptus teretiusculus. Eleven taxa are recorded here for the first time. Much new morphological information is provided regarding previously known species and 3 lectotypes are selected. The trilobites are largely endemic and indicate a quiet and comparatively shallow water environment

The origin of a suite of ultrabasic and basic rocks from the Letovice crystalline complex in the eastern part of the Bohemian massif, Czechoslovakia, is discussed on the basis of new geological and geochemical data. Strongly serpentinised spinel peridotites, plagioclase peridotites and pyroxenites, together with metagabbros, amphibolites and minor dykes of metadolerite, make up about 70% of the complex; metasediments, mainly mica schists, make up the remaining 30%. The ultramafic and mafic rocks constitute parts of a dismembered ophiolite considered to have been formed in the Cadomian episode. They show effects of polyphase deformation and were variously metamorphosed under conditions of greenschist to garnet amphibolite fades at 400–600°C and 2–5 kb. Geochemical features of the ultrabasic suite are similar to those of other ophiolite complexes, such as those of Bay of Islands, Oman, Papua, Pindos, Sarmiento and Troodos and are likely to be products of a marginal sea environment.