of the nassulids A Furgasonia and B Nassula . Stomatogenesis in both these genera is mixokinetal , initially involving kinetosomal proliferation from both somatic and oral kinetosomes ( a ). In Furgasonia , assembly of the adoral structures involves proliferation from right to left ( b ), and as the developing oral polykinetids rotate ( c ), the differentiation is completed from anterior to posterior and right to left ( d ). In Nassula , pro- liferation ( b ) and assembly ( c, d ) of the polykinetids also occurs from right to left. (from Eisler & Bardele, 1986.)