THE SEA 



359 



the relation of planets to tlie sun ; as, for 

 instance, the Cape de Verde Islands t(j Africa, 

 Ceylon to India, or Tasmania to Australia. 

 Secondly, Volcanic islands ; and 

 Thirdlj'', Those which owe their origin to 

 tlie u-rowth of Coral reefs. 



-\\'liilsiHKlav Is 



Coral islands are especially nunierons in 

 the Indian and Pacitic Oceans, wliere there 

 are innumeraltle islets, in the form of rings, 

 or \vhi(/li together foiiu rino's, the rino-s them- 

 selves being sometimes made up (.)f ringlets. 

 These '•atolls" contain a circular basin of 

 yell«jwish green, clear, shallow wat-er, wliile 

 outside is the dark blue deep water of the 

 Ocean. The islands thenrselves are rpiite low, 

 with a beach of white sand rising but a few 



