This little grebe comes of a splendid line of ancestors, some of which were even more specialised for an aquatic life. These paid the price of existence along lines too narrow and vanished from the earth. The grebe, however, has so far stuck to a life which bids fair to allow his race safety for many generations, but he is perilously near the limit. Every fall he migrates far southward, leaving his northern lakes, but if the water upon which he floats should suddenly dry up, he would be almost as helpless as the gasping fish; for his wings are too weak to lift him from the ground. He must needs have a long take-off, a flying start, aided by vigorous paddling along the surface of the water, before he can rise into the air. Millions of years ago there lived birds built on the general grebe plan and who doubtless were derived from the same original stock, but which lived in the great seas of that time. Far from being able to migrate, every external trace of wing was gone and these great creatures, almost as large as a man and with sharp teeth in their beaks, must have hitched themselves like seals along the edge of the beach, and perhaps laid their eggs on the pebbles as do the terns to-day. The grebe, denied the power to rise easily and even, to ran about on land without considerable effort, is, however, splendidly adapted to its water life, and the rapidity of its motions places it near the head of the higher active creatures,--with the woodchuck near the opposite extreme. THE VOICE OF THE ANIMALS Throughout the depths of the sea, silence, as well as absolute darkness, prevails. The sun penetrates only a short distance below the surface, at most a few hundred feet, and all disturbance from storms ceases far above that depth, Where the pressure is a ton or more to the square inch, it is very evident that no sound vibration can exist. Near the surface it is otherwise. The majority of fishes have no lungs and of course no vocal chords, but certain species, such as the drumfish, are able to distend special sacs with gas or air, or in other ways to produce sounds. One variety succeeds in producing a number of sounds by gritting the teeth, and when the male fish is attempting to charm the female by dashing round her, spreading his fins to display his brilliant colours, this gritting of the teeth holds a prominent place in the performance, although whether the fair finny one makes her choice because she prefers a high-toned grit instead of a lower one can only be imagined! But vibrations, whether of sound or of water pressure, are easily carried near the surface, and fishes are provided with organs to receive and record them. One class of such organs has little in common with ears, as we speak of them; they are merely points on the head and body which are susceptible to the watery vibrations. These points are minute cavities, surrounded with tiny _cilia_ or hairs, which connect with the ends of the nerves.