I think it probable that this animal is able to and does exert the power of compressing or dilating this scroll-like pavilion to its ear, just according as it dives deeper or rises in the water, and also I am quite sure that the hair-seal has this control over its _meatus externus_, from what I have seen of it. I have not been able to verify it in either case by actual observation; yet such opportunity as I have had gives me undoubted proof of the fact that the hearing of a fur-seal is wonderfully keen and surpassingly acute. If you make any noise, no matter how slight, an alarm will be given instantly by these insignificant-looking auditors, and the animal, awaking from profound sleep, assumes, with a single motion, an erect posture, gives a stare of stupid astonishment, at the same time breaking out into incessant, surly roaring, growling, and “spitting,” if it be an old male. This spitting, as I call it, is by no means a fair or full expression of a most characteristic sound or action, so far as I have observed, peculiar to fur-seals alone, the bulls in particular. It is the usual prelude to all their combats, and it is their signal of astonishment. It follows somewhat in this way: when the two disputants are nearly within reaching or striking distance, they make a number of feints or false passes, as fencing-masters do, at one another, with the mouth wide open, lifting the lips or snarling so as to exhibit their glistening teeth; with each pass of the head and neck they expel the air so violently through the larynx as to cause a rapid _choo-choo-choo_ sound, like steam-puffs as they escape from the smoke-stack of a locomotive when it starts a heavy train, especially while the driving-wheels slip on the rail.