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the horny covering of a bird’s bill. The rhamphotheca forms the culmen on the upper jaw and the gonys on the lower jaw. It usually consists of one piece, but in cormorants, gannets, geese, skuas, and Procellariiformes it is made up of separate parts. The rhamphotheca may have various growths and teeth, and there is a cere in the proximal section of the rhamphotheca. Molting of the rhamphotheca usually involves the continual breaking and falling away of the horny layer; less frequently it falls off all at once, as in the seasonal molt of grouse.