The propulsive mechanism of the dinoflagellate transverse flagellum reconsidered.

As a result of the recent discovery that the transverse flagellum of dinoflagellates does not beat helically within the cingulum it has been necessary to formulate a new model for the manner in which this flagellum can impart a forward motion to the cell. It is theorised that the contribution to forward propulsion by the transverse flagellum can only arise directly from an asymmetry of the flagellar wave. In addition we have drawn attention to topographic features of the cell, and particularly of the left sulcal list, which may augment this thrust by redirecting cingular flow down the sulcus.