From all that has been ascertained up to now, it would seem that the transmission of tegumentary leishmaniosis scarried out by different species of Psychodids amongst them Phlebotomus papaiasii, Phlebotomus intermedius and Phlebotomus argentipes. The epidemiollogy, the geographic superpoition between the area in which these insects exist and the area in which the disease is found, together with the results of the attempt to 'ransmit experimentally the disease by phlebotomi, all speak very much in favour of this. Phlebotomi must not only transmit tegumentary leishmaniosis, but also Indian Kala-azar, as is demonstrated by experiment made up to date and very probably they are the transmitters, as yet unproven, of leishmaniosis infantum. It is always possible for a very active focus of tegumentary leshmaniosis to arise in a zone in which phlebotomi are plentiful, as happened in Aguas Ferreas, at the end of the valley of Larangeiras and well within the town of Rio de Janeiro. Facts observed in Aguas Ferreas 'entirely exclude the idea that leishmanias might be normally harboured by phlebotomi. Other blood-sucking invertebrates (mosquitos, flies, ticks, bugs etc.) up to now accused of possibly transmitting tegumentary leihmaniosis do not appear to be able to do this. Besides dogs, no other animal is proved to be able to act as a reservoir of the virus of tegumentary leishmaniosis and it is altogether unlikely that lizards should be able to act as such.