Evolution of Ciliary Feeding in the Prosobranchia, with an Account of Feeding in Capulus Ungaricus

Ciliary currents concerned with rejection of sediment from the mantle cavity of pectinibranch Prosobranchia consist of A, currents carrying heavier particles to the inhalent opening; B, currents carrying medium particles across the floor of the mantle cavity; C, currents carrying fine particles over and between the gill filaments for later consolidation by the mucus from the hypobranchial gland. Material in currents B and C is rejected from the exhalent opening. 2. The feeding currents in ciliary feeding Prosobranchia represent modifications of these rejection currents. 3. In Vermetus novae-hollandiae currents B and C only are modified, material being passed to the mouth region, where it is mixed with mucus from the large pedal gland, by way of a food groove. 4. In Crepidula fornicata and other Calyptraeidae all currents are modified for feeding and there is an endostyle for mucus secretion.