 A survey in Monkey Bay in 1964 found two endemic species of snails of the genus ("B. nyassanus" and "B. succinoides") in the lake, and two non-endemic species ("B. globosus" and "B. forskalli") in lagoons separated from it.The latter species are known intermediate hosts of bilharzia, and larvae of the parasite were detected in water containing these, but in experiments C. Wright of the British Museum of Natural History was unable to infect the two species endemic to the lake with the parasites.The field workers, who spent many hours on and in the lake, did not find either "B. globosus" or "B. forskalli" in the lake itself.