CONTENTS 



CHAPTER PAGE 



List of Plates ....... xi 



Preface ....... xiii 



I. Introductory ....... i 



Definition of a fish. Position in the animal kingdom. 

 Difference between fish and Cetacean. Classes of fishes. 

 Numbers of species and individuals. The science of ichthyo- 



. II. Form and Locomotion ..... 9 



Shape of a typical fish. Fins and their functions. Other 

 animals with a fish-like form. Departures from the ideal form, 

 and compensating factors. Depressed and compressed fishes. 

 Flat-fishes. Fishes with rounded bodies : Globe-fishes, 

 PuflTers, Sun - fishes, etc. Elongate fishes. Sea Horses. 

 Methods of locomotion. Muscular movements. Swimming 

 of Mackerel, Eel, and Trunk-fish. Locomotion by means of 

 fin movements: caudal fin, dorsal and anal fins, pectoral 

 fins. Jet propulsion. Speed. Swimming positions. Leaping. 

 Burrowing. 



III. Respiration ...•••• 33 

 How fishes breathe. Structure of gills in Selachians, in 

 Marsipobranchs, in Bony Fishes. Lophobranchs. Process 



of respiration in a t^^Dical fish, in Lampreys and Hag-fishes, 

 in Rays, in Trunk-fishes. Does a fish drink? Gill-rakers and 

 their uses. Rate of breathing. Fish that can live out of 

 water. Accessory organs of respiration: breathing through 

 the skin, intestinal respiration, labyrinthic organs, air- 

 breathing sacs. Air-bladder and its functions. Origin and 

 evolution of air-bladder. 



IV. Fins 54 



Different kinds of fins. Their origin and evolution. Struc- 

 ture of fins: dorsal and anal, pectorals and pelvics, caudal. 

 Types of tail. Development of tail. Modifications of dorsal 



and anal in different fishes, of caudal, pectoral and pelvic 

 fins. 



V. Skin, Scales, and Spines ..... 84 

 Structure of skin. Dermal denticles of Selachians. Tail- 

 spine of Sting Rays. Saw-fishes. Scales of Bony Fishes : 

 ganoid scales, cycloid and ctenoid scales. Tubercles. Bony 

 scutes. Armoured fishes. Bony plates, rings, spine.?. Scales 



42093 



