"His scientific name is _Damalis Senegalensis_," said Doctor Bronson, "and he belongs to the family _Antilopeæ_, of which there are many varieties. Africa has more of them than the rest of the world together, and they surpass all others in beauty and numbers. There are no antelopes in Madagascar or Australia. There are a few varieties in Asia, and only one each in Western Europe and America. Look at the one I have just killed; it will weigh at least four hundred pounds when dressed, and if you measure him at the shoulder, as you would a horse, you will find he is nearly five feet high. I doubt if any one ever saw so large an antelope as this in America." Frank made note of the fact that the prize which had fallen to the Doctor's rifle had a skin which glistened like that of a carefully-kept horse, and was in excellent condition. The face and ears were black, and there was a strip of black along the shoulder and down the back and legs. The tail was longer than that of the American antelope, and had a tuft of hair at the end. After looking at the antelope, and seeing him dressed and quartered, the boys tried to break into one of the ant-hills, in order to examine the interior. They found it nearly as hard as stone, and as they had brought no pickaxes or other digging tools from the steamer they soon abandoned the effort. Abdul said they would find the inside full of passages, leading to a chamber in the centre, where the ants made their home during the season of floods. The ants are divided into workers, soldiers, and idlers, and thus Frank thought they evinced an affinity with the human race. Doctor Bronson told him the workers were much more numerous than the soldiers; the latter were five or six times as large as the workers, and had powerful jaws, with which they could bite severely. Fred asked if these ants were "slave-makers." He had read of slave-making ants, and thought, naturally enough, that in the land of the human slave-hunter and slave-owner the ants might follow the example of their betters. "These are not the slave-makers," was the reply, "or at any rate it has not been clearly demonstrated that they indulge in the practice of maintaining involuntary servants. The one known as a slave-maker is a red ant, somewhat smaller than the one before us. His habits have been studied, so that there is no doubt of his slave-holding propensities. [Illustration: A SLAVE-MAKING ANT, MAGNIFIED.]