remarked in fishes a certain degree of anhelation during the heat of summer, and at other times again, a kind of leisurely gaping,[2241] as it were. And then, besides, we have the admission of those who are of the contrary opinion, that fishes do sleep; but what possibility is there of sleeping[2242] without respiring as well? And again, we see their breath disengaged in bubbles which rise to the water’s surface, and the influence too of the moon makes even the very shells[2243] grow in bulk. But the most convincing reason of all is, the undoubted fact that fishes have the power of hearing[2244] and of smelling, two senses for the operation of both of which the air is a necessary vehicle; for by smell we understand nothing else than the air being charged with certain particles.[2245] However, let every person form his own opinion on these subjects, just in such way as he may think best. Neither the balæna nor the dolphin has any gills.[2246] Both of these animals respire[2247] through vent-holes, which communicate with the lungs; in the balæna they are on the forehead,[2248] and in the dolphin on the back. Sea-calves, too, which we call “phocæ,”[2249] breathe and sleep upon dry land—sea-tortoises also,[2250] of which we shall have more to say hereafter. CHAP. 7. (8.)—DOLPHINS. The swiftest[2251] not only of the sea animals, but of all animals whatever, is the dolphin.[2252] He is more rapid in his movements than a bird, more instantaneous than the flight of an arrow, and were it not for the fact that his month is situate much below his muzzle,[2253] almost, indeed, in the middle of the belly, not a fish would be able to escape his pursuit. But Nature,[2254] in her prudence, has thrown certain impediments in his way; for unless he turns, and throws himself on his back, he can seize nothing, and it is this circumstance more especially that gives proof of his extraordinary swiftness. For, if pressed by hunger,[2255] he will follow a fish, as it flies down, to the very bottom of the water, and then after holding his breath thus long, will dart again to the surface to respire, with the speed of an arrow discharged from a bow; and often, on such occasions, he is known to leap out of the water with such a bound, as to fly right over the sails[2256] of a ship.