CASSELL'S NATURAL HISTORY. 



COMMON PIKE. 



CLASS PISCES. FISHES. 



CHAPTER I. 

 GENEKAL INTRODUCTION. THE ANATOMY AND OTHER CHARACTERISTICS OF FISHES. 



Immense Vaiiety of Forms Charactenstics of the Class Industrial Importance to Man Fecundity Colour Mental 

 Endowments Their General Structure The Lowest Type of Fish Structural Features in Sharks and Rays The 

 Skull Peculiarities in the Lepidosiren Skull of Codfish The Sense Capsules Teeth and Jaws The Branchial 

 Arches The Muscles of Fishes The Skin and Mucous System To what Causes the Colour of Fishes is Due The 

 Scales of Fishes Agassiz's Classification based on Scales The Nervous System The Spinal Cord The Brain Organs 

 of Smell, Sight, and Hearing The Electric Organs The Teeth of Fishes The Alimentary Canal The Liver The 

 Air-bladder The Blood The Heart The Gills Fins and their Functions Classification of the Fishes. 



FISHES are the only primary division of the Vertebrata which live in water, and have no repre- 

 sentatives passing their lives upon land or in the air. This condition of existence is probably 

 the cause of the close correspondence in bodily form in the majority of fishes, which progress through 

 the water chiefly by movements of the tail, and use the fins as organs with which to steer a path. 

 Clear as is the idea which rises in the mind at the mention of a fish, the multitudes of forms 

 which fishes exhibit are greater, perhaps, than those to be found in any of the preceding great 

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