The swiftest not only of the sea-animals, but of all animals whatever, is the dolphin.[128] He is more rapid in his movements than a bird, more swift than the flight of an arrow, and were it not for the fact that his mouth is much below his muzzle, almost, indeed, in the middle of the belly, not a fish would be able to escape his pursuit. But Nature, in her prudence, has thrown certain impediments in his way; for, unless he turns and throws himself on his back, he can ............