76 THE STORY OF LIFE IN THE SEAS. 



plunging into the water, but they execute a 

 series of rapid jumps with extraordinary rapid- 

 ity from root to root or rock to rock, and so 

 avoid their pursuers. Their existence is really 

 an amphibious one, and their food consists partly 

 of Insects on the wing. Their gills are very 

 much reduced in size, and it seems probable, 

 from observations that have been recently made, 

 that their respiration is partly carried on by the 

 thin skin between the rays of the tail-fin. 



Another animal extremely abundant in the 

 Mangrove-swamps of Celebes, and, like Perioph- 

 thalmus, having a very wide distribution in 

 similar places in other tropical countries, is the 

 " Caller-crab " Gelasimus. These Crabs are about 

 an inch in breadth across the back, and are re- 

 markable for possessing one very much enlarged 

 and brightly-coloured claw, the others being 

 normal in size and dull in colour like the rest of 

 the body. On first entering the swamp at low 

 tide there may be seen on the mud between 

 the roots of the trees a number of bright yellow, 

 blue or green objects, which, as the traveller 

 approaches, disappear one by one into holes in 

 the ground. When the eyes are accustomed to 

 the gloom of the swamp these bright objects are 

 seen to be the great claws of the " Caller-crabs," 

 the rest of the body being inconspicuous owing 

 to its close resemblance in colour to the slimy 

 ground. 



These are the principal and most abundant 

 marine inhabitants of the swamps, and as has 

 been pointed out, all of them are more or less 

 amphibious in habit. More locally distributed, 



