These birds are inhabitants of the warm regions of Africa, Asia, and America; only one species, the Green Ibis, being found in Europe. They are to be met with in companies of seven or eight together, in moist and marshy grounds, and on the banks of large rivers, where they catch the worms, water-insects, and small mollusks which form the principal part of their food. They also crop young and tender aquatic plants. Their nature being mild and peaceable, they do not keep shifting about with that petulance which characterises some of the Grallæ, but have been observed to remain for hours in the same place engaged in digging into the mud which conceals their small prey. Like nearly all the other birds of this order, they migrate every year, and undertake long journeys from one continent to another. They are monogamous, each pair swearing, as it were, eternal fidelity to one another, and death alone can sever the bonds fortified by affection and habit. They usually build their nests on lofty trees, but sometimes on the ground; the female lays two or three whitish eggs, which hatch in from twenty-five to thirty days. There are eighteen to twenty species of the Ibis, of which three only merit our attention. These are the Sacred Ibis, the Green Ibis, and the Scarlet Ibis. The Sacred Ibis (_Ibis religiosa_) is about the size of a Fowl. Its plumage is white, with black at the extremity of the wings and on the rump. It has enjoyed celebrity from ancient times, on account of the veneration of which it was the object by the Egyptians. They set it up in their temples as a divinity, and allowed it to multiply in their cities to such an extent that, if we can believe Herodotus and Strabo, it actually impeded the traffic. Whoever killed an Ibis, even by accident, at once became the victim of a mad crowd, who stoned him pitilessly; and the dead bird was embalmed with the greatest care, and then placed in earthen pots hermetically sealed, which were ranged in special catacombs. A large number of mummies of the Ibis have been found in the _nécropoles_ of Thebes and Memphis, and several specimens of them are to be seen in the Museum of Natural History at Paris. [Illustration: Fig. 135.--Sacred Ibis (_Ibis religiosa_, Cuv.).] The Egyptian worship of the Ibis is a certain and incontestable fact. Less certain, however, is the origin of these honours. Herodotus has given an explanation, obscure enough, it is true, but which, however, was adopted by his successors, and for a long time accepted by our _savants_. "The Arabians assure us," says Herodotus, "that the great veneration which the Egyptians render to the Ibis is caused by the gratitude which they feel towards them for ridding the country of _winged serpents_."