MOUTHS AND JAWS 113 



move slowly in the direction of a group of " minnows," looking 

 for all the world like a drifting log of wood. Placing its jaws 

 in a suitable position, and carefully sighting its victim, the Gar 

 gives a sudden, convulsive, sideways jerk of its head, at the same 

 time endeavouring to grip the prey between its jaws. It seems 

 to be possessed of infinite patience, for many are the preliminary 

 manoeuvres and tentative snaps before the body of the little 

 fish is finally transfixed by the teeth. When this is accom- 

 plished the victim is gradually worked round into a convenient 

 position, and unless it has again escaped during this process, 

 is finally swallowed, generally head first. 



The Gar-fishes (Fig. 47B) and Sauries, on the other hand, are 

 equally voracious, but feed in large shoals, pursuing and 

 capturing their prey whilst skimming along at the surface of 

 the water, frequently transfixing the eyes or bodies of smaller 

 fishes with their ram-like "beaks." Small fishes form the main 

 item in their diet, but almost any animal substance is eaten. 

 Some of the larger species of Gar-fish, perhaps five or six feet 

 in length, may even be dangerous to man. The well-known 

 Skipper or Saury {Scombresox saurus) of our own south-western 

 coasts is an avowed enemy of the Pilchard, and should the 

 two fishes be enclosed in the same net great damage is done 

 to the "catch." 



In the curious Half-beaks or Balaos {Hemirhamphidae) , related 

 to the Gar-fishes and found in all tropical seas, only the lower 

 jaw is produced, and forms a long, spear-like projection, to 

 which a bright red membrane is usually attached (Fig. 470). 

 The teeth are minute and the diet is purely a vegetable one, 

 consisting largely of green seaweed. It is of interest to note 

 here that in both the Gar-fishes and Half-beaks the jaws are 

 of equal length and are not drawn out in the young. In the 

 young Gar-fish the jaws soon begin to lengthen, and for a 

 time the lower jaw is longer than the upper, and the little fish 

 resembles a Half-beak. The upper jaw soon increases further 

 in length, however, and in the adult fish is longer than the 

 lower {cf. p. 336). 



In the grotesque Snipe Eels {Nemichthyidae) both the jaws are 

 prolonged and not infrequently curved in opposite directions, 

 the one upwards, the other downwards (Fig. 320). 



In the tribe of Sword-fishes (Xiphiidae), Spear-fishes, and 

 Sail-fishes (Istiophoridae) only the upper jaw is prolonged, 

 forming in the first named a long, flattened, sword-like weapon, 

 and in the others a rounded, tapering spear of varying length 



