THE great diversity of form shown by the gametes of the Protozoa is well known. Even among the Foraminifera they may be amœboid, for example, Patellina1, Spirillina2; or flagellate, at least at one stage. Of the latter, to mention only one feature, some may have but one flagellum as in Gromia3,4, but in the more typical Foraminifera they are usually represented as having two ; for example, Trichosphœrium5, Iridia, Planorbulina and others6, Polystomella (Elphidium)7,8, "Tretomphalus"9 (perhaps, as Myers suggests, a pelagic phase of a species of Discorbis). In the case of Discorbis (Discorbina), we have the very convincing account by Foyn10 of a life-cycle for D. vilardeboana which includes biflagellate gametes of a similar kind ; but Myers11 has also described and figured triflagellate gametes in D. patelliformis in California. As he himself remarks, “three is a most unusual number” for the flagella of gametes of either plant or animal organisms ; indeed it is unique.