SPINY-RAYED FISHES. 69 



like a boat. Sword-fishes are the largest of Acanthopterygians, [Case 13. J 

 and not exceeded in size by any other Teleostean ; they attain 

 to a length of from 12 to 15 feet, and swords have been obtained 

 more than three feet long, and with a diameter of at least three 

 inches at the base. This sword forms a most powerful weapon. 

 Sword-fishes never hesitate to attack large Whales, and after 

 repeatedly stabbing these animals they generally retire from the 

 combat victorious. The cause which excites them to these attacks 

 is unknown; but they follow this instinct so blindly that they 

 riot rarely attack boats or large vessels in a similar manner, 

 evidently mistaking them for Cetaceans. Sometimes they actually 

 succeed in piercing the bottom of a ship^ endangering its safety; 

 but, as they are unable to execute powerful backward move- 

 ments, they cannot disengage their sword, which is broken off by 

 the exertions of the fish to free itself. A piece of a two-inch 

 plank of a whale-boat, thus pierced by a Sword-fish, in which the 

 broken sword still remain s^ is exhibited, as well as a second block 



Fig. 53. 



Block of wood pierced by Sword-fishes. 



of wood, from a ship, pierced by three swords. Attacks by small 

 Sword-fishes on the frail canoes of the natives of the South-Sea 

 Islands or on the stronger boats of the professional Sword-fish 

 hunters are of common occurrence, and only too often the persons 

 sitting in them are dangerously wounded. 



The Gobiidte and Discoboli (Case 13) are two closely allied 

 families in which the ventral fins are usually united to form an 

 adhesive disk. The former contains numerous species, small 



