MESSEL; AN INSIGHT INTO THE HISTORY OF LIFE AND OF THE EARTH, edited by Stephan Schaal and Willi Ziegler, Clarendon Press, Oxford. ISBN 0 19 854654 8. 322 pages. £50 Hardback. TRILOBITES, by H. B. Whittington, Boydell Press, Woodbridge 1992. ISBN 0 85 115 311 9. £39.95. EXERCISES IN INVERTEBRATE PALEONTOLOGY, by Frank K. McKinney, Blackwell Scientific Publictions. Oxford, London, Edinburgh, Melborne, Paris, Berlin, Vienna, 1991. ISBN 0 86542 074 2, £18.50.