The mouth-parts of male mosquitos are referred to in many text-books, but the descriptions given by various authors differ to a quite remarkable extent. This fact is particularly noticeable in regard to the maxillae and the mandibles. It is usually (and correctly) pointed out that maxillae are present in the male proboscis ; but the statements made by different observers concerning the length of these organs are extremely discordant. As to whether the male proboscis contains mandibles in addition to maxillae, opinions are sharply divided, the majority of writers asserting (as we shall see, incorrectly) that such is not the case.