294 "ALBATROSS" TROPICAL PACIFIC EXPEDITION. 



northern part is crowded with shoals, coral patches, sand bars, and sand 

 flats (PI. 226, fig. 5). 



We skirted along the southwest shore of the atoll of Ailinglap. On the 

 sea face the beaches consist alternately of shingle beaches, coral sand 

 beaches, and ledges of beach rock coral conglomerate. There are compara- 

 tively few cocoanut trees on the islands, but there is a belt of vigorous scrub 

 vegetation and large hardwood trees close to the shingle beach (PI. 168, 

 figs. 1, 2, 4). The outer reef platform has a uniform slope from the base 

 of the beach, where the beach conglomerate crops out to the outer Nulli- 

 pore knolls rising on its outer edge. The beach conglomerate is usually of 

 a yellow color, forming a marked contrast with the black, weather-beaten, 

 pitted and honeycombed shingle, which rises in a steep slope immediately 

 behind the beach conglomerate (PI. 168). The first gap we passed showed 

 no secondary lagoons ; it was barred on the lagoon side by a low island with 

 sandy beaches, on either side of which existed a passage into the lagoon. 

 The shores of the islands forming the entrance to the passes were flanked, 

 as was the outer beach, with yellow beach rock conglomerate, and a steep 

 shingle or coral sand beach rising behind it (PI. 168, fig. 1). The black 

 shingle beaches are more continuous than the sand beaches. The west 

 coast of Ailinglap is deeply indented by bays (PI. 168, fig. 2), formed by 

 the throwing up of sand from the lagoon side on the outer reef flat, into 

 elongated spits, separated here and there by reaches of yellow beach rock 

 conglomerate and forming a kind of secondary lagoon, differing somewhat 

 from those we have observed in other groups (PI. 168, fig. 2). 



The wide reef flats characteristic of Ailinglap slope gradually to the outer 

 edge; they are covered with numerous ledges and blocks of yellow beach 

 rock (PI. 168, figs. 2, 3). The prevailing wind blows nearly parallel with 

 the trend of the eastern coast. Pandanus and a belt of scrub trees form the 

 characteristic vegetation of the islands on the land rim of the west side of 

 Ailinglap ; only few cocoanut ti'ees are found on the majority of the islands 

 on the western face. The islands on the west coast are well wooded 

 and separated by narrow gaps ; they have been formed on a wide reef 

 flat, which, as we could see at the southwest pass, extends far into the 

 lagoon (PI. 226, fig. 5) ; sand bars and sandy islets separated by intricate 



