A monograph of the Ordovician trilobites of the Bala area, Merioneth.

by Whittington, H. B. (Harry Blackmore)

British Ordovician cystoids /

by Paul, C. R. C. (Christopher R. C.)
London (c/o Institute of Geological Science, Exhibition Rd., S.W. 7) : Palaeontographical Society, 1973

British Ordovician and Silurian Proetidae (Trilobita) /

by Owens, R. M. (Robert M.)
London : Palaeontographical Society, 1973

Pelmatozoan columnals from the Ordovician of the British Isles /

by Donovan, Stephen K.
London : Palaeontographical Society, 1986