The geographical and temporal distributions of the British Carboniferous Bryozoa have been determined, incorporating data from fieldwork (including localities in Scotland, North England, North Wales, South Wales, and Avon), museum collections, and literature searches. A total of 126 species has been recognised, though further work may reveal some synonymies within this list. The forty species collected during the fieldwork have been identified by reference to previous taxonomic work; most species can be assigned to established taxonomic descriptions, but two new species, Rhombopora bancrofti and Polypora hexagonaria, are proposed, and the descriptions of Rhombopora incrassata and Rhombopora similis are emended. The applicability of Student's t-test to the morphometric analysis of Carboniferous bryozoan species has been studied, and a computer program written to perforin this task, incorporating a database of species measurements. A new statistical method, the division t-test, is presented in this thesis; this method is useful in comparing the relative ratios of bryozoan colony parameters. Both the t-test and the division t-test were found to be of use in identifying bryozoan species. Analysis of the bryozoan faunas in nine regional areas of Britain has been made using the Simpson and Jaccard coefficients of similarity. The resulting coefficients are consistent with the limited distribution capability of many bryozoan taxa, and also match with the known palaeogeography and palaeocurrents of the Carboniferous of northwest Europe. Plots of species diversity against geographical distribution show a similar pattern to that produced by Tertiary non-planktotrophic larvae-bearing neogastropods. Further, additional plots of species diversity against species longevity produced a pattern consistent with normal background extinction events. A study of bryozoan morphology between different areas and different stages within the Carboniferous indicated that species showed no measurable temporal evolutionary or lateral geographical changes through the Lower Carboniferous. Rather, local environmental stresses are the major architects of bryozoan colony morphology.

Westphalian non-marine bivalves in Nova Scotia inhabited fresh to brackish temporary lakes. A series of lacustrine facies are identified on the basis of the faunas. Myalinid genera including the probably pseudoplanktonic Curvirimula, and Naiadites dominate the middle Westphalian A to early Westphalian B. Carbonicola occurs rarely in the late Namurian to early Westphalian A and is the only reported Anthracosiid. Anthraconauta dominates the upper Westphalian C to early Stephanian occurring in a wide range of sediments. The elongate Anthraconaia arenacea group range through the Westphalian D and occur in coarser lithologies. Small-shell Anthraconaia inhabited ephemeral lake margins. Cluster and principal components analysis are used to classify the faunas. The method requires the measurement of a small number of linear and relatively uncorrelated morphological variables and allows the construction of reproducable pictographs. Three new morphospecies are described. Principal components analysis is used to study morphological variation with respect to palaeoenvironment. Consistent morphological trends occur in Naiadites and Anthraconauta and are considered to have been the product of spat selection and phenotypic changes. With increased turbulence and sedimentation rates, the shell's centre of gravity is shifted towards the anter-umbonal region and the bivalves adopt a semi-infaunal mode of life thus, the morphological changes offer increased stability. Evolution was inhibited by the absence of marine incursions and progressive environmental change. Such palaeoenvironmental changes that did occur were local. Competition may have been of evolutionary importance in younger communities of Anthraconaia. The bivalves are of limited stratigraphical use as compared to the British faunas. In conjuction with micro- and macrofloral work, the Namurian/Westphalian A and Westphalian C/D boundaries are lowered and a possible Cantabrian stage recognised. A correlation with the British Chronozones is attempted.

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