CHARACTERISTICS.--These birds are characterised by the beak being raised,
and the upper mandible being arched, so that the edges of it go beyond
those of the under mandible. The nostrils are covered with a convex
cartilaginous membrane; the tail is composed of more than twelve
feathers; the toes are connected as far as the first joint. Most of the
species feed on grain, which is softened in their crops. I only know of
six species that can be tamed in the house.