CORAL-REEFS. n 9 



innumerable islets united into great rings rise above the 

 stated level. The Gilbert group is very narrow, and 300 

 miles in length. In a prolonged line from this group, at 

 the distance of 240 miles, is the Marshall Archipelago, 

 the figure of which is an irregular square, one end being 

 broader than the other; its length is 520 miles, with an 

 average width of 240 : these two groups together are 1,040 

 miles in length, and all their islets are low. Between the 

 southern end of the Gilbert and the northern end of Low 

 Archipelago, the ocean is thinly strewed with islands, all 

 of which, as far as I have been able to ascertain, are low ; 

 so that from nearly the southern end of the Low Archi- 

 pelago, to the northern end of the Marshall Archipelago, 

 there is a narrow band of ocean, more than 4,000 miles 

 in length, containing a great number of islands, all of 

 which are low. In the western part of the Caroline 

 Archipelago, there is a space of 480 miles in length, and 

 about 100 broad, thinly interspersed with low islands. 

 Lastly, in the Indian Ocean, the archipelago of the 

 Maldivas is 470 miles in length, and 60 in breadth; that 

 cf the Laccadives is 150 by 100 miles : as there is a low 

 island between these two groups, they may be considered 

 as one group of a thousand miles in length. To this may 

 be added the Chagos group of low islands, situated 280 

 miles distant, in a line prolonged from the southern 

 extremity of the Maldivas. This group, including the 

 submerged banks, is 170 miles in length and 80 in breadth. 

 So striking is the uniformity in direction of these three 

 archipelagoes, all the islands of which are low, that Captain 

 Moresby, in one of his papers, speaks of them as parts 

 of one great chain, nearly 1,500 miles long. I am, then, 

 fully justified in repeating, that enormous spaces, both in 

 the Pacific and Indian Oceans, are intersper ed with islands, 



