The lophophore and ciliary feeding mechanisms of the brachiopod Crania anomala (Müller)

Abstract

Orton's account of ciliary mechanisms on the lophophore of Crania anomala (Müller) is confirmed. Observations on the natural orientation of the lophophore have modified his account of the filter-feeding water currents. As in other brachiopods the lophophore divides the mantle cavity into inhalant and exhalant chambers with separate apertures to the exterior. The inhalant chamber has two apertures, is ventral in position, and extends into the interior of the spiral brachia; the exhalant chamber is dorsal in position and has three apertures. The development of the lophophore in the later growth stages is described. Both in development and in the form and function of the organ in the adult, the lophophore of C. anomala closely resembles that of the articulate species Tegulorhynchia nigricans (Sowerby): it is suggested that this reflects an inherent limitation on the possible variety of lophophores in brachiopods.