COASTLINES 



have seen, the mud-skipper takes in both kinds: from 

 the atmosphere into its gill-chambers, and from the 

 water through its partly-submerged tail. Unlike the 

 mud-skipper (which can survive for as long as thirty-six 

 hours out of water if it submerges its tail at intervals, 

 but only for half that time if it breathes through its gills 

 alone) the serpent-head has no rigid time limit for 

 remaining on land, provided it has access to moisture in 

 grass. It seems to have adapted itself to gill-breathing of 

 atmospheric air without discomfort. 



The climbing-fish, or climbing perch, is another fish 

 which can remain for long periods on the shore. It is a 

 spiny-rayed fish, and is characterized by the enlarged 

 and peculiarly labyrinthine structure of its superior 

 pharyngeal bones — those of the cleft, or cavity, forming 

 the upper part of the gullet. These bones are wonderfully 

 formed of infinitely delicate plates, enclosing the air- 

 spaces between them in a microscopically complex 

 mesh. 



This labyrinthine organ is also found in other fishes, 

 but is far more elaborately developed in the climbing 

 perch, in which it serves as a breathing organ of in- 

 credible complexity and efficiency. To a fish like the 

 climbing perch, which inhabits small stagnant pools 

 (where the water contains only a small amount of dis- 

 solved air) when not climbing, such an apparatus is 

 indispensable, for the creature breathes free air regularly 

 like any land animal with lungs. Its habit of leaving the 

 water and climbing trees is an extraordinary one which 

 usually occurs during rains, when it will ascend the 

 trunks of palm-trees to a height of six or eight feet, to 

 catch insects. The habit is so well known to the natives 

 of the West Indies that the animal has been known to 

 them as "the fish that climbs trees" from time im- 

 memorial; but the stories were regarded as travellers' 

 tales until quite recent times. 



The truth of the story was finally established by the 



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