Feeding, defecation, palp behaviour and motility of the tubicolous annelid, Magelona alleni were observed in a laboratory environment. Both surface deposit, and to a lesser extent, suspension feeding were exhibited, with the ingestion of sand grains, and of smaller amounts of foraminiferans and administered commercially available suspension. Predominantly sand could be seen moving through the gut, resulting in conspicuous defecation, not previously observed in other magelonid species. During this ‘sand expulsion’ behaviour, individuals turned around in a network of branched burrows. The posterior was extended from the burrow and substantial amounts of sand were expelled in a string-like formation, involving mucus. The posterior morphology of M. alleni differs greatly compared with other European magelonid species, in possessing a large terminal anus, likely related to its diet. In contrast to what has been recorded for other magelonids, M. alleni appears predominately non-selective. The current paper adds credence to the idea that multiple feeding modes exist within the family. Tube-lined burrows were observed to be primarily permanent, and motility of the species reduced in comparison to other magelonids. The differences noted between M. alleni and other species is most likely linked to its tubicolous lifestyle. The effect of environmental parameters on observed behaviours is discussed.

The very large trilobite Taihungshania miqueli occurs abundantly in siliceous nodules in the Ordovician of the Montagne Noire, southern France, but in these, larval individuals are not preserved. At a new locality at Peret, near Cabrières, protaspid and early meraspid growth stages occur in great abundance, together with a few complete specimens belonging to meraspid degrees 1, 2, 3, 5 and 7, and a single young holaspis. Although this material is largely flattened, and the originally globular protaspides crushed, it is still possible to establish the development of several axial rings before the transitory pygidium becomes liberated. In the degree 0 meraspis, the cephalon and transitory pygidium are about the same size, and the presence of a partially enrolled degree 3 meraspis indicates that protective coiling was possible by this early stage. Palpebral lobes are incipient in degree 2 meraspides, and fully formed by degree 7, otherwise the morphology of the cephalon becomes quite adult-like by degree 4. The pygidial spines begin to appear in degree 5, at which stage there are about 10 axial rings; there are about 13 in a degree 7 meraspis, and in the adult, where the posterior contour is semi-elliptical, there are some 22. The smallest hypostomes present belong to a degree 6 meraspis, and these are morphologically similar to those of adults. Observations on the later growth stages were made on material from another locality (Caramaou), as well as that from Peret. In the eye the upper lenses are large and slightly separated, but those towards the base are much diminished in size; this is a function of an unusual growth geometry.

At Peret, all stages of development, at least as far as young adults, are represented, albeit often in a fragmentary state. As with other asaphines, the protaspides are assumed to be planktic, and T. miqueli presumably left the plankton and became benthic between the protaspid and meraspid periods.

The ontogeny of Parabolina spinulosa is described on the basis of material from Andrarum (Skåne) and Jämtland in Sweden. Protaspides are rare, and indifferently preserved, but well-preserved isolated tagmata and complete specimens from the early meraspid stages onwards were available for study. Whereas the ontogeny is broadly similar to that of the earlier Olenus wahlenbergi, there are subtle differences, notably in a greater spinosity from the earlier stages and a gradual, rather than a sudden, change of surface sculpture in the early holaspid. P. spinulosa at all stages of growth is much more variable than is Olenus. Meraspides have larger articulating halfrings anteriorly and the first thoracic segments are of greater sagittal length than in the adult; these were adaptations which enabled Parabolina to undergo cylindrical enrollment from an early stage.

Parabolina is considered to have arisen from the earlier genus Olenus, and on the basis of comparative ontogeny many, though not all, features of Parabolina appear to be of paedomorphic origin. These include the reduction of the preglabellar field, retention of the visual surface, position of the eyes set close to the glabella, retention of a conterminant hypostome, yoking of the librigenae, spinosity of the thorax and pygidium, more numerous glabellar furrows and reduction in number of thoracic segments. Olenus attenuatus has several features intermediate between those of earlier Olenus species and Parabolina, and the origin of the latter genus is best considered in terms of a mosaic paedomorphocline.

The upper Cambrian trilobite Olenus wahlenbergi Westergård, 1922 occurs abun- dantly in stinkstone concretions in the Alum Shales at Andrarum, in Skåne, southern Sweden (Olenus/Homagnostus obesus Zone). All growth stages from anaprotaspis onwards are represented, though the early stages are comparatively uncommon and complete specimens are rare. Fine details of structure are preserved, suitable for scanning electron microscopic study.

The protaspis has five axial rings, which in the adult become divided transversely and reduced to three, and the preglabellar field expands markedly in the holaspis. The librigena broadens during development and the eye, with its widely separated lenses is retained on the librigena throughout meraspid development. The visual surface dehisces during ecdysis from the early holaspid onwards, due to emplacement of the ocular suture. The hypostome apparently changes from a conterminant to a natant condition in the early holaspis, which is consistent with the growth of the preglabellar field at this stage. The transitory pygidium has a slightly serrated margin throughout development, but becomes entire when all thoracic segments have been liberated.

Cuticular sculpture changes dramatically throughout ontogeny. Large (Type A) tubercles appear on the fixigena in early meraspides; these become prominent and coalesce by the end of meraspid development. They are abruptly replaced by smaller (Type B) tubercles in the early holaspid, which link to form a rough network in mature specimens. Comparable Type A tubercles in early meraspid librigenae give rise to a strong polygonal caecal sculpture in holaspids, while a radial sculpture on the broadening anterior border develops independently. The significance of these cuticular changes remains obscure. A median occipital organ is described for the first time in the Olenidae.

Collections from the Barr Group (late Llanvirn to early Caradoc) of the Girvan district are described and occurrences of all trilobites from both the Barr and Albany groups are listed and their frequencies recorded. The close relationships with North American faunas are emphasised, and three Girvan and North American species are considered synonymous. One new species is described, Bevanopsis phyllisae. Pandaspinapyga is considered a junior subjective synonym of Acanthoparypha. The possibility that Alwynulus may be an aberrant staurocephalid is discussed.

Growth stages of several genera are illustrated; some show unexpectedly large differences in size and morphology in comparison with North American silicified species at the same general stage of development.

The Carboniferous trilobite Paladin eichwaldi shunnerensis (King 1914), at its type locality in northern England is exceptionally well-preserved, and shows all stages of growth from the degree 0 meraspis onwards. The post-protaspid ontogenyis described here with particular reference to the development of cuticular sculpture. On the dorsal surface of the smallest specimens a polygonal network of raised ridges (cell polygons) is apparent. With size increase, granules progressively appear amongst the polygons, which in turn change into large tubercles as the polygonal network fades. As the trilobite grows into an adult, the tubercles become relatively smaller, and pits, the openings of cuticular canals, appear amongst them. Marginal terrace lines become pronounced. On the hypostome, however, terrace lines become effaced centrally, while large pits develop. In the early meraspis the eyes are “schizochroal”, but the lenses rapidly become closely packed and contiguous and the eye is soon of “holochroal” type. The meraspid phase is passed through very rapidly. Whereas the earlymeraspis could not enroll, its pygidium could be bent down vertically, and this facility might have allowed the larva an escape reaction.

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

All trilobites known from the Ardwell Group, Craighead Inlier, Girvan district are listed and frequencies recorded. Encrinuroides lapworthi n. sp. from the Sericoidea Mudstones, and Bumastoides fornax n. sp. from the Kiln Mudstones, are described. The Sericoidea Mudstones constitute a deeper water interlude in the complex succession which comprises the Craighead Limestone Formation; graptolites from this horizon indicate low Dicranograptus clingani zone. The closest resemblance of the trilobite assemblage as a whole is to faunas of Trenton age in North America. The occurrence of forms allied to Boda Limestone (Ashgill) species suggests that these are long-ranging, carbonate associated, trilobite stocks.

All trilobites known from the lower and upper Balclatchie and lower Ardwell groups of the Girvan district are listed and frequencies recorded. Eight new species are described, a number of generic assignments are new, and hitherto undescribed parts are illustrated. Of the 60 named species, 19 occur in the lower and upper Balclatchie and lower Ardwell groups; the upper Balclatchie Group yields the largest number of species. The assemblage is generally indicative of outer shelf conditions of deposition; a deeper water association at certain Balclatchie Group localities consists of 5 species identical with, or closely related to, species from the Liberty Hall facies of the lower Edinburg Formation of Virginia, U.S.A. This deeper water element constitutes a significantly larger proportion of the trilobite assemblages at certain localities than it does at others. A further 8 species from the Balclatchie Group are allied to lower Edinburg Formation forms, thus confirming the evidence of the brachiopods regarding the strong North American affinities of the fauna. The Balclatchie conglomerate is considered to be the result of a catastrophic event accompanied by slumping near the shelf edge causing the instantaneous entombment of the fauna.