This is an egg of that very curious fish which we call the Skate, and which looks something like one of the “flat” fishes with a long whip-like tail. So it is sometimes called a “skate-barrow.” When it is flung up on the beach by the waves the egg is nearly always empty. But if you happen to be staying by the sea-side in the early spring, and go down for a walk along the beach after a violent storm, you may perhaps find one of these eggs with a baby skate inside it. And if you examine the egg very carefully, you will find that while one end is firmly closed up, the other end has a slit running right across it, and that this slit is made in such a way that it allows the little fish to pass out quite easily when the proper time comes, but quite prevents any other creature from coming in.
On some parts of the coast you may often find an empty egg which is very much like that of the skate, for it is made of just the same horny material, and is of just the same shape. But at the four corners, instead of having straight projections like the handles of a barrow, it has long, twisted tendrils, just like those of a vine.
This is the egg of the Dog-fish, which is really a kind of small shark. It is not big or strong enough to be dangerous to human beings; but it is a terrible enemy to such small fishes as pilchards and herrings. For a number of these creatures form themselves into a band and go hunting together, just like a pack of wild dogs. And they will follow the shoal about day after day, snapping up the poor helpless fishes in hundreds and thousands.
When a dog-fish lays its eggs, it seems to fasten them down by their tendrils to the weeds which are growing at the bottom of the sea; and these hold them so firmly that unless the weeds are torn up with them, they never break away. At each end of the egg is a small hole, allowing a current of water to pass over the little fish inside it. And at one end there is a slit, just like that in the egg of the skate, which can only be pushed open from the inside. So the little dog-fish can get out, while its enemies cannot get in.