152 "ALBATROSS" TROPICAL PACIFIC EXPEDITION. 



pinkish yellow coating. Several species of Pocillipores grow on the outer 

 rim of the reef flat, rising to a considerable height, and forming its elevated 

 rim. On the lagoon slope, scattered Pocillipores and Madrepores are found, 

 as well as larger masses of Madrepores, Porites, and Astrasans of several 

 species growing in from two to six fathoms. Millepores grow abundantly 

 in shallower parts of the slopes, and Fungite are found on the reef flat and 

 slopes. Echinometr^ are abundant in the small cavities and pot-holes of 

 the rim and reef flats, while Echinaster, Echinothrix, Linckia, and Diadema, 

 as well as Heterocentrotus, are the most common Echinoderms of the outer 

 reef flat, spreading in the direction of the inner channel of the barrier reef. 



On the deeper lagoon slopes of the barrier and of the fringing reef and 

 the fringing reef flats, are found the same corals and Echinoderms which 

 occur on the shallower flats ; the corals, however, grow more abundantly on 

 the deeper slopes than on the flats, while the Echinoderms are more abundant 

 on the flats. 



Papiete Harbor and the adjoining reefs are interesting, as they have been 

 examined by nearly all the principal writers on coral reefs (Pis. 84 ; 85, 

 fig. 2; 89, fig. 2 ; 209). The outer reef was visited by Darwin ; it was sur- 

 veyed by the U. S. Exjiloring Expedition under Wilkes, and subsequently 

 re-surveyed by the "Challenger," a number of lines of soundings being run 

 by the "Challenger " normal to the face of the reef north of the entrance. of 

 Papiete to a depth of from 140 to 180 fathoms. Papiete Harbor is elliptical 

 in shape, about one and a fourth miles in length, three fourths of a mile in 

 width (PI. 209). On the northern half a number of flats and islets occupy 

 a great part of the harbor. The outer reef flat, which extends to the east- 

 ward from the entrance into Papiete Harbor, is about one eighth of a mile 

 in width, crowned at the sea face by a narrow ledge of coral shingle extend- 

 ing towards Taunoa Pass, where it expands into a club-shaped flat nearly 

 half a mile in width. A channel leads from the northeastern extremity 

 of Papiete Harbor to Taunoa Pass ; this channel is subdivided into irreg- 

 ular basins by spurs of the wide reef flat, running out from the fringing 

 reef which extends in an easterly direction from the Arsenal towards Taunoa 

 Village. Taunoa Pass opens into a small bay a little over half a mile 

 in length ; it is fringed on the east by a wide barrier reef flat, similar to that 



