6. The polypus[103] uses its tentacula both as feet and hands, for it brings its food to its mouth with the two that are above the mouth, and it uses the last of its tentacula, which is the sharpest of all, in the act of coition; this is the only one which is at all white, and it is divided at the extremity, it is placed upon the back; and the smooth part, in front of which are the acetabula, is called the back. In front of the abdomen, and above the tentacula, they have a hollow tube, by which they eject the sea-water which they have received into the abdomen, if any enters through the mouth. This part varies in position, and is sometimes on the right side, sometimes on the left, and by this its ink is ejected. [103] Sepia octopodia. 7. It swims sideways upon the part called the head, stretching out its feet; as it swims it is able to see forwards, for the eyes are upwards, and the mouth is placed behind. As long as it is alive the head is hard, as if it were inflated; it touches and holds with its tentacula bent downwards, a membrane is extended throughout, between the feet, if it falls into the sand, it can no longer hold by it. 8. The polypus and the above-mentioned malacia differ from each other; the abdomen of the polypus is small, and the feet are large; but of the others, the abdomen is large, and the feet small, so that they cannot walk upon them. They have also differences among each other; the teuthis is the smallest, the sepia wider; the teuthos is much larger than the teuthis, for it reaches the length of five cubits. Some sepiæ are two cubits long, and the tentacula of the polypus are as long, and even larger in size. 9. The class of the teuthos is rare, and differs in form from the teuthis, for the extremity of the teuthos is wider; and, again, the fin is placed round the whole abdomen, but it is wanting in the teuthis. It is a marine animal, as well as the teuthis. After the feet, the head of all these animals is placed in the middle of the feet, which are called tentacula; one part of this is the mouth, in which are two teeth; above these are two large eyes; between these is a small cartilage, containing a small brain. 10. In the mouth is a small piece of flesh, for these animals have no tongue, but use this instead of a tongue. After this, on the outside, the abdomen is apparent. The flesh of this can be divided, not in a straight line, but in a circle. All the malacia have a skin around this part. After the mouth, they have a long and narrow œsophagus; and continuous with this is a large round crop, like that of a bird; this contains the stomach, like a net. Its form is spiral, like the helix of a whelk; from this a thin intestine turns back, to the vicinity of the mouth. The intestine is thicker than the stomach.