MAEAKI. 253 



sides of the boat passage. These Porites reef flats are similar to the Mille- 

 pore and Porites flats which take such an extraordinary development in 

 Taritari, and are described in detail in the account of that atoll. They 

 show admirably how extensive areas covered with living corals like Porites, 

 Millepores, or Pocillipores, are gradually changed into dead reef flats with 

 a surface cemented by Nullipores, and become the base upon which a land 

 rim of bars or islands or islets is gradually thrown up. 



The high coarse sand beach where we landed was at least six to seven 

 feet above low-water mark. It is made up of small disintegrated fragments 

 of coral; the same is the composition of the lagoon beach, which is 

 fully as steep as the sea face, but the material of this beach contained 

 a larger proportion of broken shells. The outer spit to the south of the 

 village, near the outer face of the island, is made up of a steep coarse coral 

 shingle beach ; it is of a gray color, weathered, pitted, and honeycombed. 



On the east side of Apaiang, as far as we followed it, high coral sand 

 beaches, topped by scrub vegetation, alternate with low ledges of beach rock 

 conglomerate, forming low vertical walls slightly undercut at the base, 

 flanking the base of the sand beaches. The lagoon reef flat slopes but slightly, 

 and is covered with knolls and heads of Nullipores, Corallines, and Pocilli- • 

 pores, colored red, pink, and yellow, giving a very variegated appearance to 

 the lagoon flat ; the heads are separated by large, wide patches of sand. 

 The outer reef flat slope, where it consists of beach rock conglomerate, is a 

 brilliant yellowish brown as at Tarawa. 



From Apaiang we steamed to Maraki, one of the most interesting 

 atolls we have as yet examined. 



Maraki. 



■Plates U6-150,n3; 9.2 Ij., fig. 3. 



We steamed around the southeastern and western faces of Maraki, an 

 atoll triangular in shape, about five miles in length by three miles wide. 

 A single narrow boat passage leads into the lagoon on the western face 

 (PI. 146, fig. 1), with this exception, the land forms a continuous rim of 

 considerable height, which has been thrown up on the outer reef flat. On 



