8. For all sanguineous animals have either a bony, or a spinous column. The remainder of the bones exist in some animals, but not in others, for if they have the limbs, they have the bones belonging to them; for those that have not hind and fore legs have not hams, nor are they present in those animals which possess limbs unlike those of quadrupeds, for in these they vary in size and proportion. This is the nature of the bones of animals. CHAPTER VIII. 1. Cartilage is of the same nature as bone, but it differs in the greater and less, and neither bone nor cartilage are reproduced if they are cut off. In sanguineous and viviparous animals living on the land the cartilage is imperforate, and does not contain marrow, like the bones; but the flat selachea, which have a cartilaginous spine, have a cartilage analogous to bone containing a liquid marrow. Viviparous animals, with feet, have cartilage about their ears, nostrils, and extremities of their bones. CHAPTER IX. 1. There is another class of parts, which, though not the same as these, are not very different, as nails, hoofs, claws, and horns, and besides these, the beak of birds which alone possess this part. For these are both flexible and fissile. But bone is neither flexible nor fissile, but brittle; and the colour of horns, nails, claws, and hoofs follow the colour of the skin and the hair: for in black animals the horns are black, and so are the claws and hoofs in those with claws; in white animals they are white. There are also intermediate colours, the nails also are of the same nature. 2. But the teeth are like bones; wherefore, in black men, Ethiopians, and such like, the teeth and the bones are white, but the nails are black, like the rest of the skin. The horns of most animals are hollow at their base, and surround a bony process on their heads; but at the extremity the horn is solid and single. The stag's horns are solid throughout, and divided; and these animals alone cast their horns; this is done annually, if they are not cut off. Concerning those that are cut off, we shall speak hereafter. 3. The horns are more nearly allied to skin than to bone, so that in Phrygia and elsewhere there are oxen which have the power of moving their horns, as they do their ears; and of those which have nails (and all that have toes have nails, and those that have feet have toes, except the elephant, which has its toes undivided, and scarcely distinguished, and no nails at all)--and of those with nails, some have straight nails, like men, others crooked, as the lion among beasts, and the eagle amongst birds. CHAPTER X.