392 ALEXANDER AGASSIZ 



grown on Cape Cod), until there is only a narrow pas- 

 sage between them ; finally both horns unite and form 

 a land rim completely enclosing a lagoon and there re- 

 sults the so-called ideal atoll, so rarely seen but so often 

 described. The growth of the land rims appears to be 

 fairly rapid, for several changes could be observed during 

 the seventy years since Moresby's surveys. Some faros, 

 shown on the chart as entirely submerged, were found 

 to have little islets on their rims ; islands were found 

 to have grown into crescents, and in one case a crescent 

 was found to have completely closed about its lagoon. 



In like manner the faros forming the rim of the com- 

 posite atolls have grown up on the edge of the second- 

 ary plateaus of the great Maldive Plateau; here the 

 faros, owing to their favorable position, have obtained 

 a more extensive development, the unusually free circu- 

 lation of water permitting an abundant growth of coral 

 on their inner faces. Some of the lagoons of the faros 

 of the outer rim have been formed by the growth of 

 coral patches or lines of corals rising parallel to the 

 outer reef flat a short distance lagoonward. These 

 patches become joined and thus form elongated lagoons 

 on the outer reef flats. 



A number of tows were made in the lagoons, and as 

 might be expected from their open character, the life 

 there was found to be abundant. A number of inter- 

 mediate hauls were also made off some of the principal 

 passes. Several of the hauls * seem to have been richer 

 in masses of varied material than any Agassiz had 

 brought over a ship's side since the old days in the 



1 Intentionally somewhat limited, as Agassiz could not expect to add 

 much to the extensive collections made by Mr. J. Stanley Gardiner during 

 his prolonged stay in the Maldives. 



