In a paper read before the Royal Society of South Africa in September 1914, and published in 1915, I gave a brief description of a Herpetomonas that was found in great numbers in the cloacal mucus of Chamaeleon pumilus on Robben Island, South Africa. The flagellates were present in various stages of development in all the chamaeleons examined, i.e. about a dozen, at different seasons of the year. Attempts to cultivate the flagellates on blood agar failed owing to bacterial contamination of the media, and none were discovered in smear preparations of the lizards' spleen and liver or in blood films. Having found Herpetomonas in certain flies (Scatophaga hottentota) at that time, and it being well known that chamaeleons feed on insects, I concluded that the flagellates present in the lizard were probably derived from insects.