128 "ALBATROSS" TROPICAL PACIFIC EXPEDITION. 



existing stage, the building up of the larger island must have taken place in 

 great part from the lagoon side, judging from the comparatively small 

 amount of material derived from rolled and dead corals thrown up on the 

 northern and eastern faces of the atoll. 



On the east face of the atoll we could see the blue water marking the 

 shape of the deep indentations of the edge of- the reef flat, where the Nulli- 

 pore knolls and Pocillipore patches were unusually high, many of them 

 ready to be torn off at the next high sea and thrown vipon the reef 

 flat (PI. 77, figs. 1, 3). The Nullipore and Pocillipore knolls form the 

 outside wall of an unusually Avide and deep- platform lagoon, running 

 parallel with the western face of Nukutipipi (Pis. 76, figs. 2-4 ; 77, fig. 3), 

 which passes into the lagoon at the wide gaps of the reef platform (PL 76, 

 fig. 4). 



The soundings indicate that the sea slope of this island is very steep ; it 

 rises rapidly from a depth of more than 2300 fathoms at a distance of five 

 miles from the shore (Figs. 11, 12). 



Anu-Anurunga. 



Plates 78, 202, 203 ; 206, fig. 1. 



Anu-Anurunga is about one and a half miles in diameter; it is slightly 

 elliptical, and neither in this nor in the other islands of the Gloucester group 

 are there any boat entrances to the lagoons ; they all come within the term 

 of closed atolls (PI. 206). There are, however, a number of gaps between 

 the islands, or wide reaches of bare half-submerged reef flats, allowing free 

 passage to the sea at certain stages of the tide. 



The eastern land rim consists of two large islands, the one extending 

 from the southern point of the atoll to about the middle of the eastern face, 

 it is separated from the other large island by an islet and a wide gap awash 

 (PI. 78, fig. 1). The second island extends round the atoll to the north- 

 west side, and is separated from the western island by a stretch of reef 

 awash (PI. 78, fig. 2). The western island occupies only about a quarter of 

 the western face. The southern half of the western land rim is a reef 



