NAMU. ■ 295 



channels forming secondary lagoons extend on the lagoon side of the 

 western face of Ailinglap. 



As we go farther north, the islands and islets form a narrow land rim 

 (PI. 168, fig. 3), with low passes or gaps ; some of them were bare at half 

 tide. The wide reef flat is covered with numerous sand bars and islets 

 (PI. 171, fig. 1), forming on the lagoon side of the islands, and yet, in spite 

 of the great width of this reef fiat, the land rim did not seem to be increas- 

 ing in width, either on the sea face or on the lagoon face, much of the 

 material on the reef flats evidently being shifted backwards and forwards 

 according to the season of the year and the direction of the prevailing 

 winds. On the inner side of the lagoon, opposite its widest part, the 

 breakers due to the trade winds are high, their sweep is considerable, and 

 they must play an active part in the shaping of the land rim on the west 

 side of the atoll, exactly as do the northeast trades on the sea faces of the 

 eastern and northern part of the atoll. On the northeastern point of 

 Ailinglap the island forming the eastern edge of the horn is covered 

 with a luxuriant vegetation, and is situated on a reef flat somewhat 

 narrower (PL 226, fig. 5) than that forming the western horn of the atoll 

 (PI. 171, fig. 1). From the northern point the islands gradually pass into 

 islets and finally into low sand bars; they indicate in a general way the 

 position of the rim of the wide outer reef of the atoll. Beach rock 

 conglomerate crops out on the sea face of most of the islets and islands 

 of the western horn, and high sand beaches characterize the lagoon side 

 of the land rim. The wide outer reef flat is edged by Nullipore and 

 Pocillipore knolls ; the outer edge is deeply indented and cut, forming 

 numerous boat passages on the outer face of the reef. Tlie lagoon is 

 said to be from twenty to twenty-five fathoms deep. 



Namu- 



Plates 167, fiy. 1; 225 ; 227, fig. 1. 



Namu' is a long narrow atoll about thirty-five miles in length and a 

 little over four miles at its widest part. The western face of the atoll is 



1 Hydrog. Amt d. Reichs Marine-Amts. Plane d. Marshall Inseln. No. 113. 



