Towards the end of 1931 a study of the eggs of Anopheles mosquitos was commenced, primarily with a view to establishing any characters in the egg which may prove useful in differentiating closely allied species, and in particular those suspected of being concerned in the transmission of malaria.

The eggs of ten species of Anopheles are described and figured below : mauritianus var. ziemanni, Grünb., implexus, Theo., pharoensis, Theo., theileri var. hancocki, Edw., christyi, N. & C., gambiae, Giles (costalis, Theo.), transvaalensis, Carter, funestus, Giles, marshalli, Theo., and moucheti, Evans. Of these the writer has had the opportunity of examining specimens of Anopheles gambiae and funestus from four different regions in Uganda, namely, Kampala (3,900 ft.), Jinja (3,800 ft.), Mbale (4,000 ft.) and Fort Portal (5,100 ft.), and no local variations were observed. The eggs of two species dealt with in this paper have been previously figured by workers in other parts of the world. Edwards (1921) reproduced a drawing by Patton of the eggs of Anopheles gambiae (costalis) from Arabia, and Theodor (1924) published a drawing of those of A. pharoensis from Palestine. Both illustrations show eggs which in general structure are very similar to those of the same species in Uganda ; the sculpture of the membrane is not figured. Individual variation within the eggs of a single adult was found to be constant in the case of A. marshalli, the three forms figured being represented in each of the three batches examined.