In the Eocene great changes have taken place. The early families of bony fishes nearly all disappear. The herring, pike, smelt, salmon, flying-fish and berycoids remain and a multi tude of others seem to spring up to replace them. Among these are the bowfins, the globe-fishes, the trigger-fishes, the catfishes, the eels, the butterfly-fishes, the porgies, the perch, the bass, the pipe-fishes, trumpet-fishes, the mackerels and the John-dory, with the sculpins, the anglers, the flounders, the blen nies and the cods. That all these groups, gen eralized and specialized, arose at once is im possible, although all seem to date from Eocene times. Doubtless all of them had their origin in earlier times and the simulta neous appearance is related to the fact of the thorough study of Eocene shales which in numerous localities (Green River, London, Monte Bolca, Licata, Mount Lebanon) have been especially favorable for the preservation of their forms. Practically fossil fishes have been studied only in a very few parts of the earth. St;atland, England, Germany, Italy, Switzerland, Syria, Ohio and Wyoming have furnished the great bulk of all the fish-remains in existence. In some regions perhaps col lections may be made which will give us a more just conception of the origin of the dif ferent groups of bony fishes. We can now only say with certainty that the modern families were largely existent in the Eocene, that they sprang from ganoid stock, found in the Trias and Jura, that several of them occurred in the Cretaceous also, that the berycoids were earliest of the spiny-rayed fishes and forms allied to herring the earliest of soft-rayed forms. Few of the modern genera go back to
the Eocene; many of them arose in the Miocene; and few species have come down to us from rocks older than the encl'of the Plio cene. The general modern type of the fish faunas was determined in the later Cretaceous and the Miocene; the changes which bring us to recent times have largely concerned the abundance and variety of the individual species. From geological distribution we have arising the varied problems of geographical distribu tion and the still more complex conditions on which depends the extinction of species and of types.
For much information on the fishing appa ratus in use in America, the reader is referred to the reports of the Fisheries in the 10th census (1880), under the editorship of Dr. G. Brown Goode. In these reports Goode, Stearns, Ear11, Gilbert, Bean and the present writer have treated very fully of all economic relations of the American fishes. In an admirable work entitled 'American Fishes' Dr. Goode has fully discoursed of the food and game fishes of America, with especial refer ence to the habits and methods of capture of each. A later work of the same character is 'Food and Game Fishes of America,' by Jor dan and Evermann. A still more elaborate work is the 'Guide to the Study of Fishes,' by the present writer. To these sources and to many others of similar purport in other lands, the reader is referred for an account of the economic and the human side of fish and fisheries. See FISHES, GEOGRAPHICAL DIS TRIBUTION OF; ICHTHYOLOGY.