In these four groups of cartilaginous Fish, and the four distinct sections of bony Fishes, with their numerous sub-divisions, may be classified all the different Fishes that have become known, through all the careful research of modern Naturalists. Not that they could all be described in this limited space; nor, in fact, even given separate mention. Very few have a clear idea of how many different kinds of Fishes there really are. In the long ago, when Naturalists first made a study of the inhabitants of the water, and began to write the results of their researches, it seemed surprising to them to discover nearly a hundred distinct species. In their different families, Pliny, the Naturalist, described ninety-four species of Fish. Later Linnaeus characterized four hundred and seventy-eight. And, marvellous as it may seem, the Naturalists of the present day know upwards of thirteen thousand, a tenth of which are fresh water Fishes. While all these numerous species may possess some distinct peculiarity, they are sure to possess other characteristics that will classify them with some of these families. And after becoming familiar with the characteristics of this limited number of groups and families we may feel acquainted, to a certain extent, with this whole great throng of nearly thirteen thousand Fishes. We often hear the fact regretted, that so many of the larger Fish live almost entirely by devouring smaller species. And taking into consideration the immense quantities consumed by mankind each year, not only as they are caught fresh from the water, but the hundreds and thousands of barrels and cans of dried and pickled Fish that are shipped all over the world from the great Salmon and Cod and Herring fisheries, it is sometimes thought that, in time, the different species of Fish must surely be exhausted. But when we think of this marvellous number of species, and then remember the quantities of a single kind sometimes found in a single shoal (like that of the Herrings, quoted, in which twenty-two millions were caught in two days), there appears to be little danger of the Fishes becoming scarce; for it seems almost past belief that there can be so many finned inhabitants of the vast waters that comprise nearly three-fourths of the surface of the globe. Transcriber's Note: Some punctuation has been corrected without note, however inconsistent spelling and hyphenation were retained. Some page numbers in the table of contents have been corrected and/or rearranged to match the actual page order. Many headings in the table of contents do not correspond directly to the headings in the text. These were left as printed. Missing page numbers in internal references were added. The order of illustrations was changed in order to place the illustrations near to the text describing them. The line 'Caracal Defending His Booty from' in the list of illustrations was moved to correspond to the correct illustration.