108 



FISH GALLERY. 



are then seized by them and swallowed, 

 cattle-fishes. 



Fie. 95. 



They feed also largely on 



Lower view of head of Saw-fish. 



[Case 42.] The Rhinobatida (Case 42) contain the genera Rhynchobatus, 

 Rhinobatus, and Trygonorhina. A fine series of Rhynchobatus 

 ancylostomus, with preparations of its curious dentition, is exhibited 

 in a separate case in the middle of the Gallery. They feed on 

 hard-shelled animals, and attain scarcely a length of 8 feet. They 

 are confined to the coasts of tropical and subtropical seas. 



The Torpedinida, or Electric Rays (Case 42). — The electric 

 organs with which these fishes are armed are large, flat bodies 

 lying one on each side of the head ;^they consist of an assemblage 

 of vertical hexagonal prisms, whose ends are in contact with 

 the integuments above and below. The fish gives the electric 





