David Brown died on March 25th at the age of 68 years after enduring a long illness with much fortitude. He made a major contribution to the taxonomy and systematics of freshwater snails, with special emphasis on those belonging to the genera Bulinus and Biomphalaria, the intermediate hosts of the tropical and sub-tropical  parasitic disease bilharzia (schistosomiasis). He published over 100 papers in scientific journals and a major scholarly work, his book on Freshwater snails of Africa and their Medical Importance which was highly praised and will be the prime reference source for biologists working in this area for years to come.

In anticipation of his Memorial Service he wrote ' The natural world has been my lifelong inspiration. I never forgot finding snails in the iris patch at the age of three and the excitement of getting to know the small creatures to be found by a child at grass level. Why should there be so many differences in kinds and colours? Since boyhood it seemed plain to me that all life has evolved according to Charles Darwin's explanation of natural selection, and he has been my hero.'.. There seems little doubt that natural history had a tremendous influence throughout David's life.

He was born in Westcliffe-on-Sea, Essex on April 27th 1935, and moved temporarily to Ashtead, Surrey after the Army requisitioned his parent's house in Leigh-on-Sea, and then to Slad, near Stroud and finally to Charmouth, Dorset at the height of the German bombing. It was at this time that David , with his brother Michael, collected burnet moth cocoons, elephant hawkmoth caterpillars, netting sticklebacks and searching for toads and grass snakes. At the end of the war David returned with the family to Leigh-on-Sea to continue his education at Highfield Preparatory School and Westcliffe High School. At the University of Leicester David read Zoology, and then completed a field and laboratory study for his PhD under the supervision of Prof H P Moon on the food and feeding mechanisms of two species of mayfly. At Leicester he played the piano in a jazz band: music remained a lifelong interest. However, it was at this stage of his career that he made a change of direction that was going to influence his work for the remainder of his life. He was recruited by the Medical Research Council to the external scientific staff as a 'young biologist' and was placed in the Experimental Taxonomy Unit (now the Biomedical Parasitology Research Division in the Department of Zoology) of the British Museum (Natural History) (now The Natural History Museum) in 1959. The Experimental Taxonomy Unit was then led by Dr Christopher Wright, who took David to the Medical Research Council's laboratories in The Gambia for his first field mission; here they collected and identified the freshwater snails that are responsible for transmitting blood flukes (schistosomes) which cause the disease schistosomiasis. This disease is a major parasitic disease which affects an estimated 200 million people in over 70 countries in the tropics and subtropics, and is also of veterinary importance. David's second field trip to Africa was a six month visit in 1962 to Ethiopia, where he was based in the University of Addis Ababa. This field study led to a significant contribution to the understanding of the freshwater snails of Ethiopia. On his return to London David made a visit to Dr Georg Mandahl-Barth in Copenhagen, Denmark who was recognised at that time as a leading authority on African Freshwater Snails. David found he had much in common with Dr Mandahl-Barth and made regular visits to Denmark for scientific discussions of mutual interest until Dr Mandahl-Barth's death in April 1994. David played his part in helping Mandahl-Barth and others to develop a teaching course on malacology. 

In 1963, a few days after his marriage to Julia Shackleton, they set sail from Southampton to Durban, South Africa where David was seconded to the Medical Research Council of South Africa. Five happy and productive years were spent in South Africa, initially at the Bilharzia Research Unit, Nelspruit, Eastern Transvaal with Dr John Pitchford where they carried out a survey in the Sabie-Sand game reserve of the prevalence of bilharzia (schistosomiasis) in the African population and of the snail intermediate hosts. Further visits to Ethiopia, unravelled much about the polyploid series (snails with different chromosome numbers within the Bulinus genus), the relationship of the distribution of snails of different ploidys with altitude, and the importance of tetraploid snails of the B.tropicus/truncatus species complex in the transmission of the schistosome parasites. These studies led to a seminal publication in the Journal of Zoology. After a relatively short stay of three years in London at The Natural History Museum, interrupted by his final visit to Ethiopia in 1969, David moved to East Africa with his wife and two sons to the Kano Plain Project in Kisumu, Kenya. This was a joint project between the Medical Research Council, UK and the Kenyan Ministry of Health to study the effects of irrigation on arboviruses and bilharzia. Over a period of 5 years David surveyed the freshwater snails of the Kano Plain and made collecting expeditions over much of Kenya. These studies led to the description of new species of freshwater snails and to a series of publications on the distribution of freshwater snails of Kenya. His book on the Freshwater Snails of Africa and their Medical Importance  was begun at this time.

He returned to The Natural History Museum in the mid 70s to work on his collections and to complete his magnum opus 'Freshwater Snails of Africa and their Medical Importance' first published in 1980: David, a skilful artist, drew the line drawings with clarity.  David was awarded his Doctorate of Science in 1981 by the University of London, and a second edition of his book was published in 1994. In recognition of his contribution to malacology at least four new species of snail have been named after David by other workers.

David also wrote 'My greatest sadness has been the damage caused to the natural world by mankind, and my greatest hope that we will do more to protect what is left to enrich the lives of future generations.' With these thoughts in mind David enjoyed much happiness managing his wood, an area of old woodland comprised of Pound and Furzefield Woods in the Sussex Weald, with his son Peter to the benefit of the fauna and flora, indeed maximising biodiversity. It was much to David's satisfaction that his wood was designated a Site of Nature Conservation Importance (SNCI). In his retirement he at last found time to carry out a survey of ground beetles and hoverflies in Pound Wood, and also took part in the Sussex Buttterfly survey. David donated a legacy to the Essex Wildlife Trust to help purchase an area of land on the Langdon Hills, including a nature reserve. Other interests included bridge, photography, walking in the Swiss Alps or on the Sussex Downs, and politics where he supported Julia in her role as a local Liberal Democrat councillor.

After his formal retirement from the Medical Research Council he was appointed a Scientific Associate at The Natural History Museum which enabled him to continue his fundamental studies on the taxonomy and sytematics of freshwater snails:  one of his last papers was on the genus Gyraulus of Australia. In the latter part of his life David helped many young biologists to publish their research findings through his editorial skills on a number of scientific journals, including  the Journal of Molluscan Studies. He was Associate Editor for 10 years, and was editor for mollusca in the Journal of African Zoology. He was a fellow of the Institute of Biology, The Linnean Society of London, The Royal Entomological Society and the Zoological Society of London: a member of the British Society for Parasitology, the Malacalogical Society and the Systematics Association. Although seriously ill and even during chemotherapy, he continued to visit the Museum to put his original notes and observations in order for the archives and to make them readily available for freshwater malacologists of the future to consult.

He is survived by his wife Julia, three sons and five grandchildren all of whom gave him enormous pleasure.

Vaughan Southgate