370 Agassiz — Albatross Expedition to the Eastern Pacific. 



To the west of Au Kena and Aka Maru, lying between them 

 and the line of the outer barrier reef islets, a similar but shal- 

 lower and flat basin exists, off the northern end of Manga 

 Reva, between it and the northern horn of the barrier reef, 

 with from 7 to 11 fathoms. Its rim is formed by a ring of 

 reef patches of varying size. 



On two occasions we visited the outer barrier reef and 

 examined the outer line of islets of the eastern face of the 

 Gambier Islands. The position of the islets as marked on the 

 chart is not that of to-day, and the position of the reef flats is 

 not accurate. The position of Tekava and Tauna appears to 

 be correct. Opposite Au Kena and in its extension, the east 

 face of the barrier reefs projects sharply to the east, forming 

 an angular horn with one island south of the horn and the 

 other north, running at sharp angles with it, so as to form a 

 triangle which makes a deep bright opening westward to such 

 an extent that when off the northern side of the horn we could 

 see Tekava far to the westward of it. The second island is 

 followed by a third and then by an island (Tarauru-roa) nearly 

 2 miles long; these are separated by small gaps. Then comes 

 a larger island (Amon) followed by three small islands sepa- 

 rated by deep gaps. 



At Vaiatekeue (not the Vaiatekeua on the chart), the w reef 

 flat becomes quite narrow ; it is hardly more than 100 yards 

 wide ; the islets perhaps 50. The northern islets are small 

 and separated by long stretches of low shingle and carry but 

 little vegetation and very few cocoanut trees. There are but 

 two short sand beaches all the way from the northeastern to 

 the eastern horn of the eastern face of the encircling reef of 

 Manga Reva. A regular dam of shingle from 10 to 14 feet 

 high, on the top of which the usual coral reef vegetation flour- 

 ishes, extends along the outer face of the reef flat, which varies 

 from 50 to 150 yards in width, and is flanked at the base by 

 low buttresses of modern elevated coral reef rock and of brec- 

 cia in places, all more or less weather beaten and honey-combed. 



The islets and their formation and their junction or division 

 into larger or smaller islets and the gaps which separate them, 

 the mode of formation of the buttresses, of the planed-off, hard 

 nearly level reef flat, of the coralline mounds of the outer 

 edge, — all these differ in no way from what has been described 

 in other barrier reef islands and atolls of the Pacific. 



The beaches of the lagoon are steep, and corals do not seem 

 to thrive in those parts of the lagoon to which the sea does not 

 have access or at some distance from shore. This is well 

 shown by the vigorous growth of corals in the fringing reef 

 to the south of Mt. Duff on the outer edges of the reef patches 

 of Port Rikitea, and on the spits which connect Au Kena with 



