This fish belongs to quite a different group, which may be distinguished by two points. In the first place, its skeleton is made not of bone, but of gristle; and in the second place, five rows of shield-like bony plates run along the back and sides of the body, forming a kind of natural armor. The sturgeon is often eight or nine feet long, and weighs three or four hundred pounds. It spends most of its life in the sea, but ascends the rivers in order to spawn, like the salmon. It is not so common as formerly in American waters, although sturgeon are taken in nearly all our larger rivers from time to time; but in some parts of Europe, and especially in Russia, it is very plentiful. Caviare is made from the sturgeon's roe. The membranes which separate the eggs from one another are all removed, and the eggs are then salted and pressed into small barrels, being afterward eaten as a kind of preserve. The best isinglass is made from the sturgeon's swimming-bladder, which has so much gelatine in it that, if a small quantity is dissolved in a hundred times as much boiling water, it will form a stiff jelly when it is cold. The sturgeon's flesh is very good to eat, for it is not only well-flavored, but is so firm and solid that it is almost like beef. In England the sturgeon is known as a "royal" fish, because, in days of old, when one of these fish was caught in an English river, it was always kept for the table of the king; and even now, if a sturgeon is captured in that part of the Thames which is under the control of the Lord Mayor of London, it belongs by right to the Crown. THE BEAKED CHÆTODON A great many fishes are very odd to look at, and this is one of the oddest. Imagine a fish with an almost circular flattened body, with five brown bands edged with white running round it, huge round eyes, enormous triangular fins both above and below the body, a broad tail, which looks as if it were tied in by a piece of ribbon at the base, and a mouth drawn out into a long slender beak! And this fish has a habit which is even odder still, for when it sees an insect sitting on a leaf which overhangs the margin of the sea, it takes careful aim, squirts a drop of water at it from out of its long beak, and nearly always succeeds in knocking it into the water below! This fish lives in the Indian and Polynesian seas, and is sometimes kept as a pet by the Japanese, who amuse themselves by fastening a fly to the end of a piece of stick and holding it over the bowl in which the fish is living, in order to see it knocked off its perch by a pellet of water. THE COD Throughout the northern seas the cod is found, and in some parts it is taken in immense numbers. The largest and finest of all, which sometimes weigh more than one hundred pounds, come from the banks, or shallows in the sea, off the shores of Newfoundland, but very fine ones have been taken elsewhere; and extensive cod-fisheries are maintained in the North Pacific, near Alaska.