the range of several species (25). Loss of finland is responsible for the decline of many species in the genus Vertigo such as V. angustior V. geyeri V. genesis and V. moulinsiana which are widespread but very local and found only in calcareous fens and marshes. Woodland species and relic species with small ranges are particularly vulnerable, including Elona quimperiana Catinella arenaria Truncatellidae arcyensis Vallonia sp, Trichia sp. and Trochoidea geyeri (39). Elona quimperiana for example, is found only in the west of Brittany, France and in north eastern Atlantic coastal areas of Spain in deciduous forest and damp headlands. Its biology and ecology are poorly known and there is concern that it could become endangered through habitat loss moil). In the U.S. A. surveys have revealed many species threatened through habitat loss. In the eastern U.S.A, 22 species are considered to be potentially endangered on account of their limited ranges or because they are found in areas undergoing rapid development (tf-s). For example, most forms of the well-known Florida Tree Snail ( Liguus sp) are now extinct in the Keys, eliminated by the growth of holiday homes and tourist resorts. Fortunately several have been transplanted into the Everglades National Park where they stand a good chance of survival. The Painted Snake Coiled Forest Snail Anguispira picta is threatened by lumbering in its limited area of distribution in Tennessee. Succinea ovalis chittenangoensis the Chittenango Amber Snail is known only from the spray zone talus under the waterfall after which it is named, and is vulnerable on account of its small ranee (33). Little information is available for Africa and many species have only been recorded from their type localities. In South Africa, where the terrestrial molluscan fauna is comparatively well-studied the number of endemic species is high; for example, the proportion of endemics reaches 90 per cent in the genus Gulella Many species are forest dwellers, and the area of coastal bush and forest along the east coast is particularly vulnerable. Other areas important for molluscs include the Chirinda Forest (Mt Selinda) and the Victoria Falls Rain Forest, both in Zimbabwe Ct). Terrestrial snails are even less well-studied in Asia, where many species may become extinct before they are known to science. In the Philippines, deforestation and fire had eliminated much of the endemic snail fauna by 1957, and even in Palawan, probably the least accessible and developed island in the country, much of the original fauna has probably gone (10). 2. Introduced species The introduction of carnivorous snails to many Pacific islands in an attempt to control the Giant African Snail Achatina fulica has caused enormous damage to endemic snail populations. A. fulica was confined to the African mainland and Madagascar until the beginning of the 19th century when it was introduced to Reunion Island in the Indian Ocean, purportedly for making soup for the Governor's mistress. Within a few years populations had reached pest proportions, the snail showing a preference for cultivated plants. It subsequently spread to India and colonized large areas of the Asiatic mainland, and has since spread eastwards across the Pacific, becoming established in Tahiti, the Hawaiian chain, Vanuatu and New Caledonia (12). Attempts at biological control of A. fulica were made with the carnivorous snails, Gonads quadrilateralis from Africa and Euglandina rosea from Florida (10,19). Studies carried out to investigate the effectiveness of these species have produced no satisfactory results, although one study cited decreases in the abundance of A. fulica at several Oahu sites. However, no attempt was made to determine whether this was due to predation or to disease and other factors (7,11). Results from a second study suggested that the carnivorous snails preyed selectively on juvenile A. fulica (1) but this study did not consider reproductive seasonality as a factor determining presence or absence of young A. fulica, and at least one study 160