ON THE OUTER REEF. 67 



at the surface experiences. But all animals are 

 adapted for their particular sphere in life." 



Noticing a bubbling in the sand, Dick thrust 

 his hand under and forced up what the doctor 

 declared to be a box-crab ; as he demonstrated, it 

 had the faculty of closing its legs around its 

 body in such a manner as to seem a solid piece. 

 When released, it opened out and showed its 

 curious make-up a round body, covered with 

 queer brown spots and ridges, even the claws 

 being formed in grotesque shapes. 



" You'll find lots of them crabs on the reef," 

 said Busby, who was passing. 



" Hallo, look over yonder ! " came a sudden 

 shout from Long John. * "We've got to clear 

 out of this, and be quick about it, too ! " 



They all followed the direction of his warn- 

 ing gesture, and saw on the horizon a small 

 black cloud, its lines as distinct as if drawn with 

 a brush. As they sprang into the boats and 

 pulled for Long Key the cloud seemed to in- 

 crease, and so rapidly did it gain upon them 

 that in ten minutes from the time they sighted 

 it the cloud was almost on them. Landing hur- 



