There are numerous kinds of polypi. The land2522 polypus is larger than that of the sea; they all of them use their arms2523 as feet and hands; and in coupling they employ the tail, which is forked2524 and sharp. The polypus has a sort of passage in the back,2525 by which it lets in and discharges the water, and which it shifts from side to side, sometimes carrying it on the right, and sometimes on the left. It swims obliquely,2526 with the head on one side, which is of surprising hardness while the animal is alive, being puffed out with air.2527 In addition to this, they have cavities2528 dispersed throughout the claws, by means of which, through suction, they can adhere to objects; which they hold, with the head upwards, so tightly, that they cannot be torn away. They cannot attach themselves, however, to the bottom of the sea, and their retentive powers are weaker in the larger ones. These are the only2529 soft fish that come on dry land, and then only where the surface is rugged: a smooth surface they will not come near. They feed upon the flesh of shell-fish, the shells of which they can easily break in the embrace of their arms: hence it is that their retreat may be easily detected by the pieces of shell which lie before it. Although, in other respects, this is looked upon as a remarkably stupid kind of animal, so much so, that it will swim towards the hand of a man, to a certain extent in its own domestic matters it manifests considerable intelligence. It carries its prey to its home, and after eating all the flesh, throws out the debris, and then pursues such small fish as may chance to swim towards them. It also changes its colour2530 according to the aspect of the place where it is, and more especially when it is alarmed. The notion is entirely unfounded that it gnaws2531 its own arms; for it is from the congers that this mischance befalls it; but it is no other than true that its arms shoot forth again, like the tail in the colotus2532 and the lizard.2533