78 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY. 



to be correct. Opposite Au Kena and in its extension the cast face of 

 the barrier reef projects sharply to the east, forming an angular horn, 

 with one island south of the horn and the other north running at a sharp 

 angle with it, so as to form a triangle which makes a deep bight open- 

 ing westward to such an extent that when off the northern sid« of the 

 horn we could see Tekava far to the westward of it. The second island 

 is followed by a third, and then by a long island — Tarauru-roa — nearly 

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

 island — Amou — followed by three small islands separated by deep 

 gaps. 



At Yaiatekeue (not the Vaiatekeua on the chart), the reef flat be- 

 comes 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 Eeva. A regular dam of shingle from 10 to 14 feet high, 

 on the top of which the usual coral reef vegetation flourishes, extends 

 along the outer face of the reef flat, which varies from 60 to 150 yards 

 in width, and is flanked at the base by low buttresses of modern ele- 

 vated coral reef rock and of breccia in places all more or less weather- 

 beaten and honeycombed. 



The islets, and their formation, and their junction or separation into 

 larger or smaller islets, and the gaps which separate them, the mode of 

 formation of the buttresses, of the planed-ofl", 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 Manga Reva, contrasted to those along the west face of 

 the lagoon flats to the west of the eastern barrier reef. 



There is a northeast horn of the eastern barrier reef in the extension 

 of Manga Reva Island, forming the northern culmination of the central 

 bight of the eastern face of the barrier reef. From that point the reef 

 flat runs westerly to form the northern horn about 3 miles north of 

 Manga Reva Island. The position of the outer reef cannot be correct 



