246 "ALBATROSS" TROPICAL PACIFIC EXPEDITION. 



Pocillipores and the gayly colored Nullipores growing on the outer edge of 

 the reef flat platform form, perhaps, the most striking display of colors we 

 have as yet seen, with the yellowish bi'own beach rock and the light green 

 water of the pools covering portions of the fiats, and the dark blue digitate 

 channels penetrating far into the reef flat slope. These small channels, cut 

 out of the edge of the reef flat, form convenient points for landing, and 

 along the shore we could see the canoes of the natives hauled up on the 

 beaches opposite these diminutive landing-places. 



Maiana is one of the most interesting of the Gilbert atolls. It is 

 enclosed on the west by a wide reef flat, with only two small gaps through 

 which there is free communication between the lagoon and the outer 

 sea. Undoubtedly in former times other gaps opened into the lagoon, 

 but they have, little by little, been closed by the process we have 

 described as uniting the islands and islets of the land rim in other atolls 

 of the Ellice group. 



As we passed the first gap on the southeastern .shore, we obtained 

 an excellent view of the inner part of the lagoon of Maiana, and were 

 surprised to find in the atoll a series of inner beaches running parallel 

 to the outer shore, forming huge secondary lagoons, similar to those we 

 observed in other atolls of the Ellice group. These secondary lagoons 

 are formed by incipient sand bars on the broad reef flats, which extend 

 far into the interior of the Maiana lagoon (PI. 224, fig. 6). 



We could see, at some points of the land rim, low dams (PI. 140, fig. 1), 

 indicating the position of the gaps which once connected the lagoon with the 

 sea, showing that the secondary lagoons of Maiana must have been formed 

 •by a process similar to that now shaping the secondary lagoons on the east 

 and southern coast of Apamama. These secondary lagoons are certainly 

 not due to subsidence ; they owe their origin to mechanical agencies, such 

 as we have seen at work in the atolls of Tapeteuea and Apamama. 



On the northeast face the beach changes its character ; it is made up 

 almost entirely of coarse coral shingle, and even of huge boulders of coral 

 thrown up on the steep beach on that face of the atoll (PI. 140, fig. 1). 

 Here and there, however, a coral sand beach separates the reaches of 

 shingle beach. Outliers of the beach rock conglomerate or coral breccia 



