ii CONTENTS 



CHAPTEK PAGE 



of Lung-fishes. Arrangement of scales, scale counts. Axil- 

 lary scales. Lateral line. Scale-reading and age-determina- 

 tion. Replacement scales. 



VL Mouths and Jaws . . . . . .103 



Form of mouth in Cyclostomes, in Selachians. Jaws of 

 Selachians, of Bony Fishes. Form and position of mouth 

 in Bony Fishes. Modifications of lips. Weevers and Star- 

 gazers. Gar Pikes, Gar-fishes, and Half-beaks. "Sword- 

 fishes." Tube-mouths. Fishes with protractile mouths. 

 Flat-fishes. 



Vn. Teeth and Food . . . .120 



Teeth of Cyclostomes and Selachians. Succession of teeth 

 in Sharks and Rays. Diflferent kinds of Shark dentition. 

 Man-eating Sharks. Thresher Shark. Nurse Sharks and 

 Bull-headed Sharks. Teeth of Rays. Dentition of Chimaeras. 

 Teeth of Bony Fishes. Pharyngeal teeth. Depressible teeth. 

 Feeding habits of Pike, Caribe or Piraya, Blue-fish, Lancet- 

 fish, Barracuda. Canine teeth: Chauliodus, Cynodon. Denti- 

 tion in fishes with mixed diet. Archer-fish. Plankton feeders. 

 Wrasses. Parrot-fishes and Plectognaths. Cyprinids. Stro- 

 mateoids. Unusual meals. A remarkable " Shark story." 



VI n. Venom, Electricity, Light, and Sound . .140 



Poison glands in Selachians. In Bony Fishes: Cat-fishes, 

 Weevers, Scorpion-fishes, Toad-fishes. Eflfects of venom. 

 Treatment. Fishes with poisonous flesh. Electric organs: 

 Torpedo, Electric Eel, Electric Cat-fish, Skates and Rays, 

 Mormyrids, Star-gazers. Origin of electric organs. Nature 

 of the discharge. Uses of electric organs. Luminous fishes. 

 Photophores. Other light organs. Production of light. 

 Purpose of luminous organs. Production of sound : by the 

 air-bladder, by stridulation, by elastic spring mechanism. 

 Sound-producing fishes. 



IX. Internal Organs . . . . . -159 



Skeleton: skull, vertebral column. Muscles. Alimentary 

 canal : mouth, tongue, stomach, intestine, rectum. Vascular 

 system : heart, arteries and veins, lymphatic system. Kidneys. 

 Air-bladder. 



X. Nervous System, Senses, and Sense Organs . 177 



Nervous system: brain, spinal cord, nerves. Sensory and 

 motor nerves. Olfactory organs. Sense of smell. Eyes: 

 structure, modifications, position. Sense of sight. Auditory 

 organs. Otoliths. Connection of air-bladder with internal 

 ear. Weberian mechanism. Sense of hearing. Internal ear 

 and equilibrium. Sense of taste. Of touch. Barbels. Other 

 tactile organs. Lateral line: structure, functions. Sense of 

 pain. Schooling or shoaling sense. Sleep. Reflex and 

 conscious actions. 



