Contribution to the knowledge of the family Caecidae. 4. The temporary septum formation of some caecid species (Caenogastropoda: Rissooidea)

Two successive septum formations are made by Caecum dextroversum, a species from the Panamic Province. The definitive septum is the second one and is hidden by the first temporary one until the latter is abraded and eliminated. The phenomenon is displayed by other species from the eastern Atlantic, viz. C. clarkii, C. pollicare and C. sp.