Considering the paucity of good books on tropical biology it is a little surprising that two, dealing with inland waters, should appear within a few months of each other and from the same publishers. But the viewpoints of the two authors differ to a large extent. Beadle is specially interested in how the aquatic organisms of lakes, rivers and reservoirs fit into and modify the physico-chemical environment, also with the remarkable physiological adaptations of animals to extreme conditions such

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... s the anoxic environment of tropical swamps and waters of very high temperature and salinity. From Lowe-McConnell, who has both worked in tropical America and Africa and paid visits to the Asian tropics, we have first-hand accounts of the enormous variety offish, with species ranging from the largest freshwater fish known, Arapaima gigas of South America (now classed as a disappearing species), to tiny little species, such as certain Cichlids in Lake Malawi which live by nibbling at the individual scales of larger species. She discusses them in relation to the fish communities and the total ecosystems in which they live. Both authors discuss the extraordinary adaptive radiation of the Cichlid fishes, especially in Africa, and the Characoid fishes, especially in South America, in relation to What it can teach about the processes of evolution, so we have here two different but convergent arguments concerning such problems as the suppression of gene flow between populations, 'sympatric' and 'allopatric' speciation, and the influence of predators. Of particular interest is the fact that, especially in South America, there has been a night-time adaptation of fishes to the environment separate from the day-time adaptation -a whole community of species is dominant by day but hides away at night to be replaced by a quite different community. This could be compared with day and night communities in terrestrial and aerial communities -birds by day, bats by nightwhich occupy ecological niches to the full. We should not forget also the give and take between the aquatic, terrestrial and aerial ecosystems, in which birds, mammals and insects play a major role. Now that the unit of conservation is tending to change from the species to the ecosystem, without which the species can rarely survive, there is a lot in these books of direct interest to FPS members. They are certainly among the best books on tropical inland water life yet to appear.