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Geological Society, London, Special Publications; 1967; v. 2; p. 379-395;
DOI: 10.1144/GSL.SP.1967.002.01.29
© 1967 Geological Society of London

Invertebrata

Chapter 11 Bryozoa

G. P. Larwood, Ph.D., A. W. Medd, D. E. Owen, Ph.D. F.G.S. & R. Tavener-Smith, M.Sc. F.G.S.

Hatfield College, Durham
Department of Palaeontology, Institute of Geological Sciences, Exhibition Road, London S W 7
Manchester Museum, The University, Oxford Road, Manchester 13
Department of Geology, Queen’s University, Belfast, Northern Ireland

Introduction. The arrangement of the documentation and the sequence in which family or subordinal ranges is shown on the range charts follows that of the Treatise, Pt.G (Bassler 1953). Departures from this arrangement are given in the general comment on each Order.

Although a general revision of the Treatise Pt G, is contemplated, and much taxonomic study of fossil Bryozoa is still necessary, the distributions plotted on the accompanying stratigraphic range charts appear to reflect real phases of diversification in the Trepostomata, Cystoporata, Cryptostomata and Cheilostomata. Details of diversification in the Ctenostomata are likely always to be obscure, but extensive revision of the Cyclostomata should reveal their true pattern of development in geological time [G.P.L.]

Class PHYLACTOLAEMATA Allman 1856

First, Cret Cenom: ?Plumatella proliferus Fric, Bohemia. Extant, Cristatella mucedo Cuvier, cosmopolitan.

Comment: The Phylactolaemata are freshwater Ectoprocta lacking a mineralised skeleton. They may be presumed to have a long geological history; a single imperfectly preserved specimen has been assigned to Plumatella.

Order CTENOSTOMATA Busk 1852

General Comments: The Ctenostomata are Bryozoa in which the skeleton is membranous or only imperfectly mineralised. In life they are able, by chemical secretion, to excavate hollows in the surfaces of the substrata which they encrust. Such excavations are found fossil and their form is used to diagnose zoarial characters. On this basis, three long-ranging extinct families are recognised, greatest diversification being in the Palaeozoic. Several extant families occur, but only one of these has a recognised fossil occurrence from Tert Mioc onward.

Suborder STOLONIFERA

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