Neogastropod prosobranch molluses produce species-specific egg-capsules. Two proteins, different at least structurally, are used in the production of these capsules by most species. The storage of these two proteins in the egg-capsule glands of the species Cominella maculosa was investigated in an attempt to discover whether both proteins were produced and stored separately or whether only one basic molecule was produced and stored in the gland to be subsequently used to form the two different protein structures present in the egg-capsules; ribbons and filaments. The two proteins were found to be produced and stored separately, but in very similar membrane-bounded granules or spherules. One of the proteins was found to be stored in the gland in a different structural form to that eventually used in the production of the egg-capsules.