44 ATOLLS. Cll. I. 



Moresby has communicated to me in the kindest 

 manner. 



The Maldiva Archipelago is 470 miles in length, 

 with an average breadth of about 50 miles. The form 

 and dimensions of the atolls, and their singular posi- 

 tion in a double line, may be seen, though imperfectly, 

 in the greatly reduced chart (fig. 6) in Plate II. The 

 dimensions of the longest atoll in the group (called by 

 the double name of Milla-dou-Madou and Tilla-dou- 

 Matte) have already been given ; it is 88 miles in a 

 medial and slightly curved line, and is less than 20 

 miles in its broadest part. Suadiva, also, is a noble 

 atoll, being 44 miles across in one direction, and 34 in 

 another, and the great included expanse of water has a 

 depth of between 250 and 300 feet. The smaller atolls 

 in this group differ in no respect from ordinary ones ; 

 but the larger ones are remarkable from being breached 

 by numerous deep-water channels leading into the 

 lagoon ; for instance, there are 42 channels through 

 which a ship could enter the lagoon of Suadiva. In 

 the three southern large atolls, the separate portions of 

 reef between these channels have the ordinary structure 

 and are linear ; but in the other atolls, especially the 

 northern ones, these portions are ring-formed like 

 miniature atolls. Other ring-formed reefs rise out of 

 the lagoons, in the place of those irregular ones which 

 ordinarily occur there. In the reduction of the chart 

 of Mahlos Mahdoo (Plate II. fig. 4), it was not found 

 easy to define the islets and the little lagoons within 

 each reef, so that the ring-formed structure is very im- 



