410 J. STANLEY GARDINER. 



sea from their bounding reefs. The deeper passages, although they literally teem with animals, 

 seem neither to have shoaled nor to have been at all constricted. 



The lagoon is remarkably uniform in depth, and its bottom except near passages is every- 

 where coated with mud, to which I have already referred in Appendix A, Sec. II. " On the 

 Formation of Lagoons." The shoals to the south and west of the lagoon, and to the east 

 with a few exceptions, viz. those which have been referred to with growing points, have 

 precipitous slopes from about 4 to 30 fethoms with very narrow rough areas around, strewn 

 with dead masses from the flats above. Among these sedentary reef organisms do not grow, 

 while every stone is riddled with boring animals, and very quickly destroyed. It is im- 

 possible for the larvae of sedentary animals to become affixed on a muddy bottom, and there 

 is no piling up of sand anywhere, so that what change there is in the lagoon is likely to be 

 one of loss rather than gain, an action possibly shown by an increase in depth, found especially 

 towards the south part of the atoll. 



Matu and the island opposite to it on the other side of the passage are both of coarse sand, 

 and covered with tall coconut trees. There has been a little loss to the E., but there is no marked 

 change. I could not find the shoal shown to the E. of Matu, but all others and the depths as far 

 as Wiringili are as represented. The island to the IST. of IVIametu has disappeared, and to tlie 

 S. of that island the reef has a narrow velu, extending along the whole of its length. To the 

 E. of it in the centre are two rocky masses, standing on the sand-flat behind the boulder zone 

 of the reef, their summits a foot or two exposed even at high tide. 



Wiringili is mainly formed of sand and occupies the S. end of the reef. Its lagoon-reef is 

 rather low, no part being exposed at low tide, and the shore, 200 yards behind its edge, has a few 

 fallen coconut trees but no signs of extensive loss. To the S. the island is fringed with an area 

 of coral rock, the beach lying on the inner edge of the boulder zone. The latter and the reef- 

 flat merge round the S. of the island into the reef of the W. side, while the island sends out 

 on it to the S.W. a stone-covered spit. On the east side the rock has been pierced, and the beach 

 washed back from the boulder zone. The channel between is now a bare, smooth flat, covered with 

 low green algae, but four lines of the beach rock show stages in the former washing away. The 

 boulder zone appears to be entirely a recent formation. The two sandy islets of Raverea are 

 now joined, and the single island formed is sending out a sand-spit to join one that has grown 

 out from Wiringili. Falawaru lies just inside the boulder zone and is formed mainly, if not entirely, 

 of coral rock. Its former connection to Wiringili is shown by a mass of rock halfway between 

 it and the rocky outer end of that island. A few rocks to the N. indicate a considerable former 

 extension of Falawaru along the reef towards Mametu, rock masses showing at tiie least a series 

 of islets. 



The slope from Wiringili reef to the lagoon is very gradual in its greater depths. An edge 

 is clearly defined at about 1 fathom, soundings giving 20 yards from the same 11/, 30 yds. 12/, 

 40 yds. 14/, 70 yds. 19/, 90 yds. 23/, and 100 yds. 28/ At 11/ the bottom had growing on it 

 between large, bare, sandy areas, a few small spreading colonies of MontijMra and Madrepora. The 

 reef edge is covered with coral growth, but the colonies as at greater depths are not of large size. 

 There is plenty of variety but no luxuriance, and the quantity of weed present is extraordinary 

 for such an area. 



The channel separating Wiringili from Kudu has only 13 fathoms instead of the 15 marked, 

 the soundings across from Wiringili at even distances giving 13, 13, 13, 13, 13, 13, 13, 12, 

 12, and 11 fathoms. Kudu is all sand except for a rocky point to the E., 20 yards behind the 

 boulder zone. Opposite the middle of the island a point runs out from the reef into the lagoon 



