What seems most surprising is the fact that these harmless little Fishes, which live largely on small crustaceans and small Fishes just hatched, should continue to thrive in such marvellous numbers, when its enemies are the most formidable inhabitants of the ocean. All the different members of the Whale family destroy them by the thousands, and our illustration on Page 247, where the Sword-Whales are feasting on one of the great shoals of Herring, gives a limited idea of the great quantities devoured by these great Fish. Then we must take into consideration that man, on the other hand, carries on a war which threatens to be one of extermination. In fact, the Herring fishery has been to certain nations, the great cause of their prosperity. It was the foundation of Dutch independence. But in spite of this continual war against them, the Herrings continue to thrive and increase, and they are well worthy of the place they have long held as one of the greatest friends and helpers of mankind that has been found in the animal kingdom of the great deep. THE FAMILY OF SPINY-FINNED FISHES. [Illustration: RED GURNARD.] This fourth large family of bony Fishes includes the Perch family, which is altogether a fresh water Fish; and many curious species which are found in the sea—like the Weevers, Mullets, Gurnards, Labrus, Frog-fish and Sword-fish. The well known Mackerel family is also included among the Fishes with spiny fins, with the Tunny and the curious Archer-fish. The Weevers are a good type of these spiny-finned Fishes. They bury themselves in the sand, and are dangerous to the fishermen because of the serious wounds which they inflict with their spines. THE GURNARDS. [Illustration: FLYING GURNARD.]