154 ALONG THE FLORIDA REEF. 



upon the beach, after which they explored the 

 limited area. 



" North Key," said the doctor, as they stood 

 on the sands and looked about, " may be consid- 

 ered the last of the chain of islands to the north 

 iu the waters of the Florida Reef. You see 

 there is no mangrove growth here, owing, per- 

 haps, to the strong winds which prevent the 

 seeds from taking root ; and, besides, the winter 

 northers sweep the ridge raised by the summer 

 trades, and level it so that for several months in 

 the year it is often entirely under water." 



The boys were impressed by the singular 

 sight of an island dependent upon wind and 

 wave, and Tom christened it Disappearing Island, 

 as it was always coming and going. A few 

 clumps of grass grew here and there, the growth 

 of seeds washed ashore. Even the spirit-crabs, 

 generally the first to take up a residence, were 

 absent. The white shore showed a few stranded 

 sea-snails, while delicately outlined were the 

 tracks of a sea bird, whose footprint here was 

 almost as astonishing as the one found by Robin- 

 son Crusoe. The key was deserted. No, on the 



