Through the kindness of Mons. E. Séguy, of the Muséum d’Histoire Naturelle, Paris, I have recently been enabled to examine a considerable number of mosquitos from Madagascar and the neighbouring French islands, including the types or co-types of all the species described from Madagascar by Ventrillon. As the examination of this material has disclosedthe existence of several species hitherto unrecorded from these islands, aswell as some new synonymy, it has been thought desirable to record the results at once. In the following pages all the species of mosquitos hitherto known from this region are dealt with. The total number is only 28, as compared with about 180 in the African fauna, so that it is highly probable that further collecting would produce many others.