Observations of Pellet-Casting by Horned and Pied-billed Grebes.-ln his interesting article "Feather-eating and Pellet-formation in the Great Crested Grebe" (Brit. Birds, 49: 432-435, 1956), Simmons summarizes the evidence for the theory that feathers eaten by grebes form the necessary rough material in which fish bones and other indigestible items can be ejected in the form of pelle