The crop and the gizzard of the ostrich are not separated as in other birds, but are joined; the upper part of the stomach performs the functions of a crop and the lower part those of a gizzard. The male ostrich is usually larger than the female. The adult males and females are plainly distinguished by the color of their plumage, the body feathers of the male being black, while those of the female are gray. The plumes of both sexes are white or white mixed with black. The black on an ostrich is often of a brownish shade, and this is most conspicuous when it appears on the plumes. The bill of the male and the scales on the fronts of his shanks become a bright rose color in the breeding season. The male ostrich utters a guttural sound, called booming, which is said to resemble the roar of a lion as heard at a distance. The voice of the female is like that of the male, but very faint. The difference in the plumage of the sexes, although it is not complete until after the second adult molt, is noticeable much earlier. The females do not begin to lay until three or four years old. The males are not fully matured until four or five years of age. Ostriches are very long-lived. Birds whose age could be verified have lived as long as forty-five years in captivity, and at that age were profitable as breeders and also as feather producers. It is believed by some of those most competent to judge such matters that under favorable circumstances an ostrich might live a hundred years or more. Very few of the birds kept in domestication die of old age. They are so stupid, and their long legs, though strong for running, are so easily broken, that an accident of some kind almost always ends the life of an ostrich long before it has passed its prime. [Illustration: Fig. 180. Front view of male and female ostriches. (Photograph from the Bureau of Animal Industry, United States Department of Agriculture)] The name "ostrich" has an interesting history. The Greeks called this singular bird _struthion'_. This came into the Latin language as _struthio_. In low Latin, _avis_, the Latin word for "bird," was prefixed to what remained of the Greek name, giving _avis struthio_. "Ostrich" is a contraction of this low Latin compound. So we have in this name a combination of two words from different languages, having the same meaning. The terms "cock," "hen," and "chick" are used with the name of the species, to designate respectively the adult male, the adult female, and the young before the first plucking.