The Bulletin of The Natural History Museum (formerly: Bulletin of the British Museum 

 (Natural History) ), instituted in 1949, is issued in four scientific series, Botany, 

 Entomology, Geology (incorporating Mineralogy) and Zoology. 



The Geology Series is edited in the Museum's Department of Palaeontology 

 Keeper of Palaeontology: Dr N. MacLeod 



Editor of Bulletin: Dr M.K. Howarth 



Assistant Editor: Mr C. Jones 



Papers in the Bulletin are primarily the results of research carried out on the unique and ever-growing collections of the 

 Museum, both by the scientific staff and by specialists from elsewhere who make use of the Museum's resources. Many of the 

 papers are works of reference that will remain indispensable for years to come. All papers submitted for publication are 

 subjected to external peer review before acceptance. 



SUBSCRIPTIONS Bulletin of the Natural History Museum, Geology Series (ISSN 0968-0462) is published twice a year 

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World list abbreviation: Bull. nat. Hist. Mus. Lond. (Geol.) 



ISSN 0968-0462 



The Natural History Museum Geology Series 



Cromwell Road Vol. 58, No. 2, pp. 81-168 



London SW7 5BD Issued 28 November 2002 



Typeset by Ann Buchan (Typesetters). Middlesex 



Printed in Great Britain by Henry Ling Ltd, at the Dorset Press, Dorchester, Dorset 



