252 "ALBATROSS" TROPICAL PACIFIC EXPEDITION. 



in other parts of the lagoon platform. The land rim of the east face of 

 Tarawa, as far as we examined it, consists of secondary lagoons such as we 

 have described. The secondary lagoons are not indicated on the charts of 

 Tarawa, of Maiana, Taritari, or the few atolls in the Paumotus where they 

 have been observed. 



Apaiang. 



Plates U5,fi<js. IS; :i23 ; ii24,fig. 2. 



After skirting the eastern face of Tarawa we examined the southern 

 part of Apaiang,^ an atoll about sixteen miles in length, and eight miles 

 wide across its northern extremity (PL 224, fig. 2). Its outline is formed by 

 a series of large loops, the reef flats running out into well-marked points 

 on the northern, eastern, and western faces. The principal land rim is on 

 the eastern face of the atoll, while on the wide northern and western reef 

 flats only a few low islands are found, with the exception of the larger 

 island of Nuotaea, which forms the northwestern spit of the atoll (PI. 224, 

 fig. 2). On the southwest face two well-marked ship passages lead into the 

 lagoon ; numerous shoals occur in it. 



The beach of the southeastern shore is flanked by beach rock ; outliers of 

 coarse conglomerate, separated by stretches of coarse coral sand, line the 

 shore above high-water mark (PI. 145, fig. 3). On the lagoon side of the 

 island forming the southeast point, the steep beach consists of fine coral sand. 

 Rounding the eastern point (PI. 145, fig. 2) of the south face of the atoll, south 

 of the boat passage leading into the lagoon, we found, from a depth of twenty 

 fathoms up to two, masses of corals covering the bottom ; they consist mainly 

 of Mooandrinas, Madrepores, Pocillipores, Millepores, and Alcyonarians ; 

 of special interest were a number of large sponges closely allied to species 

 found on the Australian barrier reef. As we came in through the inner 

 boat passage, the coral heads in the narrow part of the channel became more 

 and more luxuriant, especially the large blocks of Porites ; as we approached 

 shallow water, they spread horizontally ; as the tops neared the surface, 

 many of them were dead and covered with masses of white and of red Nulli- 

 pores, which form a cement over the whole surface of the reef flat on both 



1 A. Chart 732. 



