IN a recent paper1 Mr. Lowndes has put forward a new view as to the filtratory feeding mechanism of the fairy shrimp, Chirocephalus diaphanus. Hitherto all workers (Storch2, Lundblad3, Naumann4, Borradaile5, Wagler6 and Cannon7) have agreed that the long setae on the edges of the basal endites of the trunk limbs constitute the filter, or at least a retaining wall by which particles are abstracted from a current of water.