I must not pass by the birds of Diomedes in silence. Juba calls them “cataractæ,” and says that they have teeth and eyes of a fiery color, while the rest of the body is white: they always have two chiefs, the one to lead the main body, the other to take charge of the rear, they excavate holes with their bills, and then cover them with hurdles, which they cover again with the earth that has been thus thrown up; in these places they hatch their young; each of these holes has two outlets—one of them looking towards the east, by which they go forth to feed, returning by the one which looks towards the west. In one only spot throughout the whole earth are these birds to be seen—in the island which is famous for the tomb and shrine of Diomedes, lying over against the coast of Apulia: they bear a strong resemblance to the coot. When strangers who are barbarians arrive on that island, they pursue them with loud and clamorous cries, and only show courtesy to Greeks by birth; seeming thereby, with a wonderful discernment, to pay respect to them as the fellow-countrymen of Diomedes. Every day they fill their throats, and cover their feathers, with water, and so wash and purify the temple there. From this circumstance arises the fable that the companions of Diomedes were metamorphosed into these birds. We ought not to omit, while we are speaking of instincts, that among birds the swallow[186] is quite incapable of being taught, and among land animals the mouse; while on the other hand, the elephant does what it is ordered, the lion submits to the yoke, and the sea-calf and many kinds of fishes are capable of being tamed. Birds drink by suction; those which have a long neck taking their drink in a succession of draughts, and throwing the head back, as though they were pouring the water down the throat. The porphyrio is the only bird that seems to bite at the water as it drinks. The same bird has also other peculiarities of its own; for it will every now and then dip its food in the water, and then lift it with its foot to its bill, using it as a hand. Those that are the most esteemed are found in Commagene. They have beaks and very long red legs. [Illustration: KING PENGUIN.—_Aptenodytes Pennantii._] All the heavy birds are frugivorous; while those with a higher flight feed upon flesh only. Among the aquatic birds, the divers are in the habit of devouring what the other birds have disgorged. The pelican is similar in appearance to the swan, and nobody would imagine there was any difference between them, were it not for the fact that under the throat there is a sort of second crop. In this the ever-insatiate animal stows everything away, till the capacity of this pouch is quite astonishing. Having finished its search for prey, it discharges bit by bit what it has thus stowed away, and reconveys it by a sort of ruminating process into its real stomach. The part of Gallia that lies nearest to the Northern Ocean produces this bird.