RANGIROA. 47 



Funuarua is perhaps 1000 to 1200 feet wide ; the smaller islands near it 

 gradually become narrower as we pass to the westward, forming shorter 

 and shorter dams separated by channels varying greatly in width and in 

 depth (from one to two feet). 



The larger and higher islets, covered with bushes, low trees, and cocoa- 

 nuts, gradually pass into smaller and lower islets with less and less vegeta- 

 tion, until we find, as buttresses to the sea wall which separates all these cuts 

 from the sea face, mere sand bars extending into the lagoon (PI. 14). To 

 the northward are a few islands and islets, centres of such sand accumula- 

 tions, where the great sea wall and its extension into the lagoon is hidden 

 by the butt of the sand bars accumulated against it. The great sea wall 

 is inore or less cut into fragments, and open here and there to the passage 

 of breakers which roll in upon the wide ledge fiat which skirts the whole 

 southern face of the atoll, — a fiat fully two to two and one half miles wide 

 from the sea face to the two-fathom line on the lagoon side. A short distance 

 from the wall on the hrgoon side one can see the white line of breakers rising 

 above it and losing itself through the openings on the reef fiat, or appear- 

 ing in the cuts between the islands as a white line on the top of the dark 

 wall of the cul-de-sac. From the last island which we could see to the west- 

 ward (Taeroere) there is also a long stretch of this bare wall with here and 

 there a sand bar buttress on the lagoon reef fiat. 



In the large cut we examined we could trace the extension of the old 

 reef rock toward the lagoon as a more or less distinct slope of the great 

 wall until it became lost in the centre of the cut; then only occasional rocks 

 jutted out here and there above the water line to disappear and pass into 

 the slope of the lagoon ledge (PI. 16). 



On the sea face of the wall extends a reef flat platform fully 450 feet 

 wide in places, the surface of which is deeply pitted and honeycombed and 

 planed off to a general level (Pi. 17, fig. 1). On the outer edge, which is 

 somewhat higher than the depressed edge near the base of the great wall, 

 Pocillipores grow in abundance, and the whole of the platform is more or 

 less protected by a growth of encrusting Nullipores of a pink or brown 

 color. The Nullipores appear to thrive best on the raised outer edge of the 

 reef platform. With the incoming tide the water rushes into the secondary 



