44 FLYING-FISH. FAMILY SILURID^E. 



selves by striking them against it. The most usual height of 

 their flight is from two to three feet ; but they have occasionally 

 been known to spring to a height of fifteen or even twenty feet. 

 The utmost length of their flight seems to be between two and 

 three hundred feet ; and its extreme duration about thirty seconds. 

 Few spectacles are more beautiful, than the sudden rise of a shoal 

 of Flying-fish from the gently-undulating surface of the tropical 

 ocean, their scaly surface and extended fins glistening in the 

 bright sunshine with all the varied hues of the rainbow, and the 

 graceful curves in which they move at last terminated by a return 

 to their native element, from which they presently again spring 

 up with renewed vigour. These airy excursions are commonly 

 regarded as occasioned by the pursuit of Dorados, Bonitos, and 

 other fishes of prey ; but this is prpbably by no means the case, 

 for the Flying-fish seem frequently to rise from the water for the 

 mere sake of exercising, with pleasure to themselves, those powers 

 of movement with which they are endowed, just as we see 

 other fishes gambolling about in their usual medium. Whilst in 

 the air, they are often seized upon by the long-winged sea-birds. 



569. The next family, SILURIDJE, or Silure tribe, is distin- 

 tinguished by the want of scales, having only a naked skin, in 

 which large bony plates are frequently imbedded. Many of 

 them have the adipose or fatty second dorsal fin, which is a pro- 

 minent character of the next family. The species included in 

 this group are mostly river-fish, of considerable size, inhabiting 

 warm climates. Many of them have the first ray of the pectoral 

 fin very strong and bony ; and the fish can, at pleasure, lay it 

 flat on the body, or keep it fixed in a perpendicular direction, in 

 which case it becomes a formidable weapon, capable of inflicting 

 very troublesome wounds. There is no sufficient reason, how- 

 ever, to believe that these wounds are venomous. The Malap- 

 terurus, remarkable for its electrical powers, has been already 

 noticed ( 543). 



570. The two remaining groups of this order are of great 

 importance to Man, from the large supply of wholesome and 

 palatable food which they yield. The first of these is the family 

 SALMON ID^E, or Salmon and Trout tribe; which is characterised 



