THE IMPENETRABLE SEA 



perhaps leaping on to the water and skimming across it 

 like a flat pebble thrown by a schoolboy. 



Mud-skippers often chmb trees, chnging to the rough 

 bark until they reach a projecting stump or branch 

 where they can perch and survey the strange world in 

 which they live. While resting, a mud-skipper will often 

 plant its "arms" firmly — using them as organs of support 

 as a man places his elbows on the table. 



The eyes of these creatures are most ingeniously 

 devised. Not only can they be drawn in and pushed out : 

 they can also be swivelled in all directions hke the eyes 

 of a chameleon. After death the mud-skipper's eyes sink 

 to the level of the surrounding scales, losing their charac- 

 teristic prominence. 



It is beheved that these fish have been driven from the 

 sea by their numerous marine foes: the unpalatable 

 nature of their flesh giving them some measure of protec- 

 tion from land animals. 



The name ''walking-fish" is shared by some of their 

 near relatives, particularly the serpent-head, a fish of the 

 East Indian and African genus, Ophiocephalus. These are 

 able to live for long periods out of water, as they travel 

 by wriggling through moist grass from one pool to 

 another. They are from two to three feet long, and are 

 covered with medium-sized scales — those on the flat- 

 tened head being plate-like. Some thirty species of 

 serpent-heads alone are known to us, inhabiting many 

 parts of Asia ; the commonest being a species which is 

 sometimes found in a torpid condition in dried-up pools, 

 as though the water had evaporated while the fish dozed 

 — too lazy to find a better resting-place. 



When living in muddy water, these fishes are com- 

 pelled to rise to the surface at intervals or they die — they 

 are not so acclimatized to the shores as the mud- 

 skippers. 



The serpent-head or snake-fish breathes atmospheric 

 air instead of that dissolved in water ; although, as we 



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