ON THE OUTER REEF. 55 



and animal organizations is continually increas- 

 ing and enriching. That is the secret of reef- 

 building, Bush Key being an example in this 

 group of the aid which the mangrove gives." 



While the doctor had been talking, the boats 

 had slowly drifted toward the key, \vhen right 

 ahead a large sting-ray leaped from the water, 

 flapping its wing-like fins in the air a moment, 

 then coming down with a crash that was heard 

 all over the lagoon. A large fin showed itself 

 above the water, rushing after the ray toward a 

 shoal near the key. 



" It's a shark chasing a sting-ray ! " shouted 

 the old boatswain from the bow of the dinghy. 

 " Give way, lads, give way ! " 



The boat surged ahead in the direction of 

 the great fishes. The shark was gaming on its 

 less rapid victim, and the ray repeatedly leaped 

 into air to escape the rushes the shark made at 

 it. Suddenly the ray took a desperate chance 

 as it neared the shoal, and, instead of turning, 

 dashed upon it ; the flat body passed through 

 the scant eight inches of water with a rush, and 

 in an instant it was through the breakers and in 



