No bibliography has been included in this work. A list of writers so complete as to have value to the student would make a volume of itself. The principal works and their authors are discussed in the chapter on the History of Ichthyology, and with this for the present the reader must be contented. The writer has hoped to make a book valuable to technical students, interesting to anglers and nature lovers, and instructive to all who open its pages. DAVID STARR JORDAN. PALO ALTO, SANTA CLARA COUNTY, CAL., October, 1904. ERRATA[1] VOL. I Frontispiece, for _Paramia quinqueviltata_ read _Paramia quinquevittata_ Page xiii, line 10, _for_ Filefish _read_ Tilefish 39, " 15, _for_ Science _read_ Sciences 52, lines 4 and 5, transpose hypocoracoid and hypercoracoid 115, line 24, for _Hexagramidæ_ read _Hexagrammidæ_ 162, " 7, The female salmon does as much as the male in covering the eggs. 169, last line, _for_ immmediately _read_ immediately 189, legend, _for_ Miaki _read_ Misaki 313, line 26, _for_ sand-pits _read_ sand-spits 322, " 7 and elsewhere, for Wood's Hole read Woods Hole 324, " 15, for _Roceus_ read _Roccus_ 327, " next to last, for _masquinonqy_ read _masquinongy_ 357, " 5, _for_ Filefish _read_ Tilefish 361, " 26, _for_ 255 feet _read_ 25 feet 368, " 26, _for_ infallibility _read_ fallibility 414, " 22, _for_ West Indies _read_ East Indies 419, " 23, _for_-99 _read_-96 420, " 28, _for_ were _read_ are 428, " 24, _for_ Geffroy, St. Hilaire _read_ Geoffroy St. Hilaire 428, " 25, _for_ William Kitchener Parker _read_ William Kitchen Parker 462, " 32, for _Enterpneusta_ read _Enteropneusta_ CONTENTS VOL. I. CHAPTER I. THE LIFE OF THE FISH (_Lepomis megalotis_). PAGE What is a Fish?--The Long-eared Sunfish.--Form of the Fish.--Face of the Fish.--How the Fish Breathes.--Teeth of the Fish.--How the Fish Sees.--Color of the Fish.--The Lateral Line.--The Fins of the Fish.--The Skeleton of the Fish.--The Fish in Action.--The Air-bladder.--The Brain of the Fish.--The Fish's Nest. 3 CHAPTER II. THE EXTERIOR OF THE FISH. Form of Body.--Measurement of the Fish.--The Scales or Exoskeleton.--Ctenoid and Cycloid Scales.--Placoid Scales.--Bony and Prickly Scales.--Lateral Line.--Function of the Lateral Line.--The Fins of Fishes.--Muscles. 16 CHAPTER III. THE DISSECTION OF THE FISH. The Blue-green Sunfish.--The Viscera.--Organs of Nutrition.--The Alimentary Canal.--The Spiral Valve.--Length of the Intestine. 26 CHAPTER IV. THE SKELETON OF THE FISH.