108 



FISH GALLERY. 



are then seized by them and swallowed. They feed also largely on 

 cuttle-fishes. 



Fig. 95. 



mm 



Lower view of head of Saw-fish. 



j^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 



