196 CORAL AND ATOLLS 



but tlae channels are intricate and liable to considerable 

 changes from the rapid growth of coral masses. 



The growth of corals all over this part of the lagoon is 

 very luxuriant, and very large colonies of Pontes are to be 

 seen in the deep blue water ; here also large growths of 

 Millepora are seen, and both the great plates of the type 

 coinplanata and the branches of the type alcicornis are to be 

 recognised. Millepora colonies are as a rule absent, or 

 represented only by very sickly looking growths, over the 

 southern shallows ; but in the northern basin some of the 

 specimens are among the finest to be found anywhere in the 

 atoll. 



To the westward the lagoon shelves slowly to the open 

 sea, and here great masses of coral are to be seen growing in 

 the greatest profusion. The site is one in which practically no 

 sedimentation is taking place, for in any weather the sea is a 

 confused one in the gap between Pulu Luar and Pulu Panjang. 

 When the wind comes from the west, or north-west, very 

 heavy seas roll into this gap, and the whole interval is filled 

 by great white-crested rollers, making any entry to the lagoon 

 an impossibility. 



The northern basin of the lagoon presents an altogether 

 more varied picture than the southern portion, for it shows 

 every phase of the transition from shoal to submerged reef. It 

 shows at its southern limits the destruction of coral growth 

 by sedimentation, and the shallowing of the lagoon by sand 

 accumulation ; at its northern limits, the absence of sedimen- 

 tation, and the shallowing of the lagoon by coral growth. 

 Some of the coral boulders in the northern basin have grown 

 with very great rapidity, and their removal from the boat 

 anchorage opposite Pulu Tikus is occasionally necessary. 

 Most of these boulders are very large colonies of Porites, which 

 are for the most part yellow coloured, and here grow in the form 

 of slightly flat-topped spherical masses. Another part of the 

 lagoon which is undergoing considerable change, brought about 

 by the activity of coral growth, is the best channel to Pulu 

 Selma, but here it is great beds of the typical form of 



