90 



THE STORY OF FISH LIFE. 



fish and the gar-pike and half-beak is a superficial 

 In the former it is the upper jaw only 



one. 



which is elongated, and this is used as a spear ; 

 in the two latter both jaws are elongated, and 

 used as a pair of forceps, like a bird's beak. We 

 have now a third form of the elongation of the 

 jaws to examine. In this type the jaws are 



FIG. 8. A. Head of Gnathonemus elephas, one of the Mormyridse 

 from the Congo, to show the extraordinary modification of the 

 jaws (after Boulenger). B. Head of Ilistiopterus recurvirostris, 

 after Giinther, also showing modification of the jaws. 



drawn out into a long and often curved tubular 

 beak or trunk, at the extreme tip of which is a 

 tiny cleft the mouth. This beak resembles the 

 long drawn-out head of that curious mammal the 

 great ant-eater, even to the cleft-like terminal 

 mouth. This curious tubular beak is apparently 

 an adaptation enabling the fish to explore and drag 

 out from holes and crevices creatures which lie 

 hid therein. The "boar-fish" (Histiopterus) and 

 the chelmo of Australia, and some members of the 

 genus Mormyrus of the African rivers and lakes, 

 represent the most striking instances of this 



