They are polygamous birds, one male being generally seen with two or three, and sometimes with five, females. The female Ostrich, after depositing her eggs in the sand, trusts them to be hatched by the heat of the climate; in the Book of Job there is a beautiful passage relating to this habit of the Ostrich, “which leaveth her eggs in the earth, and warmeth them in the dust; and forgetteth that the foot may crush them, or that the wild beast may break them. She is hardened against her young ones, as though they were not hers. Her labour is in vain; without fear, because God hath deprived her of wisdom; neither has he imparted to her understanding. What time she lifteth up her head on high, she scorneth the horse and his rider.” It appears, however, that the female Ostrich sits upon her eggs like other birds, although generally at night only, and brings up her young. The eggs are as large as a young child’s head, with a hard stony shell, and one has been known to weigh upwards of three pounds. The time of incubation is six weeks. That Ostriches have great affection for their offspring may be inferred from the assertion of Professor Thunberg, who says that he once rode past the place where a hen Ostrich was sitting in her nest, when the bird sprang up and pursued him, evidently with a view to prevent his noticing her eggs or young. Every time he turned his horse towards her she retreated ten or twelve paces, but as soon as he rode on again she pursued him till he had got to a considerable distance from the place where he had started her. In the tropical regions, some persons breed Ostriches in flocks, for they may be tamed with very little trouble. When M. Adanson was at Podar, a French factory on the southern bank of the river Niger, two young but full-grown Ostriches, belonging to the factory, afforded him a very amusing sight. They were so tame that two little blacks mounted both together on the back of the largest. No sooner did he feel their weight than he began to run as fast as possible, and carried them several times round the village, and it was impossible to stop him otherwise than by obstructing the passage. This sight pleased M. Adanson so much that he wished it to be repeated, and, to try their strength, directed a full-grown negro to mount the smaller, and two others the larger of the birds. This burden did not seem at all disproportioned to their strength. At first they went at a tolerably sharp trot, but when they became a little heated they expanded their wings, as though to catch the wind, and moved with such fleetness that they scarcely seemed to touch the ground. The foot of the Ostrich has only two toes, one of which is extremely large and strong. [Illustration: THE RHEA, (_Rhea Americana_,)]