The Land and Freshwater Molluscs of Suffolk: an Atlas and History

Those of you who have been involved in faunal census surveys will know the effort required to maintain enthusiasm to complete such schemes. It is, therefore, particularly pleasing to see lan Killeen's study of the land and freshwater molluscs of Suffolk appear in print. Moreover, this book, which represents over ten years work on the molluscan fauna of Suffolk, principally by the author, has been produced to the high standard which it deserves.

The Atlas and History presents the distribution of all the land and freshwater molluscs (including Pisidium spp.) known to be living in Suffolk. The area studied is that of the Watsonian vice-counties of East and West Suffolk (VC's 25 and 26) and the mapping unit is the "Tetrad" (2 km X 2 km square). The two vice-counties comprise 1089 tetrads of which 74 have been examined with excess of 25,000 records.

Although the distribution maps form the basis of the book, there is a great deal more to it than that. The subtitle "An Atlas and History" is entirely appropriate. The history of recording Mollusca in Suffolk is well presented in the early chapters. The earliest record of a mollusc living in Suffolk dates from 1784 but the fossil record is also considered. Quaternary sediments which contain Vertigo geyeri and V. genesii and a Flandrian tufa which contains Discus ruderatus and Nesovitrea petronella attest to the climatic changes which have occurred in "Suffolk" in the distant past. Throughout the book, records are placed in an historical context. For each species the earliest record is presented and distribution is discussed in terms of geology, climate and habitat. These factors are themselves the subject of discussion in the opening chapters. In the case of the freshwater molluscs, the base map includes the major rivers.

Apart from the extinctions which have occurred in the geological past, Killeen's extensive research has shown that several other species no longer occur in Suffolk. For example, Zonitoides excavatus appears to have been extinguished by 1865 and Helicogona lapicida, once widely distributed in the County though always rare, was last seen in 1972. However, not all the changes observed are extinctions. In 1878 Potamopyrgusjenkinsi was first discovered in Suffolk and the process of introduction has continued with the most recent newcomer being Limax valentianus - in 1986. An outstanding example of the value of intensive studies of distribution is shown by the discovery of several sites for two rare species of vertiginid snails, Vertigo angustior and V. pusilla. In Suffolk these live together in well defined coastal wetland habitats. V. pusilla has also been found in another unexpected habitat, the broad-leaved woodland fringe of conifer plantations in the Breckland. Similarly, the discovery of Umax cinereoniger in Suffolk, the first record for East Anglia, is of considerable significance to the distribution of Mollusca in Britain. Other interesting patterns of distribution have become evident through the study. Compare the complementary dis- tributions of Oxychilus helveticus and O. alliarius; Cepaea nemoralis and C. hortensis; the stability of distribution of Arianta arbustorum with the changing pattern of distribution of Pupilla muscorum.

Undoubtedly, an outstanding feature of this book is the inclusion of Derek Rands' superb colour photographs of living molluscs. Several of the smaller species are presented in exquisite detail, although I would have liked to have seen some indication of size on these plates since this is not readily grasped in many of the photographs.

The text concludes with a list of useful addresses, references and a species index. This is a very well presented Atlas, free of errors, which, in addition to its intrinsic value, will give encouragement and set the standard for future distributional studies.