Dolphins generally go in couples; the females bring forth their young in the tenth month, during the summer season, sometimes two in number.[2257] They suckle their young at the teat like the balæna, and even carry them during the weakness of infancy; in addition to which, long after they are grown up, they accompany them, so great is their affection for their progeny. The young ones grow very speedily, and in ten years are supposed to arrive at their full size. The dolphin lives thirty years; a fact that has been ascertained from cutting marks[2258] on the tail, by way of experiment. It conceals itself for thirty days, at about the rising of the Dog-star, and hides itself so effectually, that it is not known whither it goes; a thing that is more surprising still, if it is unable to respire under water. Dolphins are in the habit of darting upon the shore, for some reason or other, it is not known[2259] what. They do not die the moment that they touch the dry land, but will die much more speedily if the vent-hole is closed. The tongue, contrary to the nature of aquatic animals in general, is moveable, being short and broad, not much unlike that of the pig. Instead of a voice, they emit a moaning sound[2260] similar to that made by a human being; the back is arched, and the nose turned up. For this reason[2261] it is that they all recognize in a most surprising manner the name of Simo, and prefer to be called by that rather than by any other. CHAP. 8.—HUMAN BEINGS WHO HAVE BEEN BELOVED BY DOLPHINS. The dolphin is an animal not only friendly to man, but a lover of music as well; he is charmed by melodious concerts,[2262] and more especially by the notes of the water-organ.[2263] He does not dread man, as though a stranger to him, but comes to meet ships, leaps and bounds to and fro, vies with them in swiftness, and passes them even when in full sail.