112 A HISTORY OF FISHES 



own kind, and it is not unusual to find a specimen which has 

 swallowed another fish several times its own bulk. Such a meal 

 is made possible by the mobility of the lower jaw, the two 

 halves of which are very loosely bound together, and can be 

 readily pulled apart in order to enlarge the gape. The Great 

 Swallower (Chiasmodon) , a curious deep-sea fish remotely 

 related to the Perches, is another form with a capacity for 

 dealing with out-sizes in meals, and here again are the same 

 flexible and distensible jaws (Fig. 91 a). Indeed, the action of 

 swallowing is carried out, not, as is usual with fishes, by means 

 of the muscles surrounding the gullet, but by the action of the 

 jaws as in the snakes. Actually, they do not so much swallow 

 the victim, as draw themselves over it. In the rare Gulpers 

 {Lyomeri) of the oceanic depths the mouth is literally enormous 

 (Fig. 91c), and both mouth-cavity and throat are capable of 



Fig. 48. 

 Long-nosed Gar Pike (Lepidosteus osseus), X \. 



immense distension, whilst the deep-sea Angler-fishes or 

 Ceratoids possess similar expanding maws. 



In the Gar Pike [Lepidosteus) of North America, and in the 

 marine Gar-fishes [Belonidae) and Sauries (Scombresocidae) , both 

 the jaws are prolonged to form a more or less lengthy "beak," 

 armed with sharp, unequal teeth. This is another example of 

 convergent evolution, for in spite of the similarity of their jaws 

 the two groups of fishes are quite unrelated. The Gar Pikes 

 (Fig. 48) are more or less solitary feeders, and subsist largely 

 on a diet of fresh-water crayfishes and small fishes of all kinds. 

 The Alligator Gar Pike {L. tristoechus) , abundant in the rivers 

 around the Gulf of Mexico, and attaining a length of twenty 

 feet or more, is very destructive to food fishes, and causes a 

 great deal of damage to the nets of fishermen, who kill it 

 without mercy. It is not even good eating itself, the flesh being 

 rank and tough, and unfit even for dogs. If one of the Long- 

 nosed Gar Pikes (L. osseus) in the tank at the Zoological 

 Society's Aquarium be observed on the feed, it will be seen to 



