150 "ALBATROSS" TROPICAL PACIFIC EXPEDITION. 



which have been eroded and washed out to sea, leaving the thin outer line 

 of reefs we have described. 



Venus Point is, like Tautira Point, a mass of volcanic sand and mud 

 which has been deposited by the Tuaura River, and the jetty built up from 

 the opposing surf of the western and eastern sides, has gradually been built 

 out so as to unite with the outer edge of a former barrier reef flat (PI. 209). 

 A wide peninsula flanked with islands and islets has thus been made, forming 

 a harbor to the east of the Brander Plantation, and forming on the west the 

 pocket of the eastern end of Matavai Bay. The islands to the east of Point 

 Venus are composed of volcanic sand, while the islets on the east face of 

 Tahiti, north of Boudeuse Pass, are mainly composed of coral sand, which 

 has been thrown up on the outer reef face upon a base of volcanic rocks. 



On several occasions I examined the north side of the Papiete barrier reef,^ 

 the same portion which was surveyed by the " Challenger," " for about two 

 miles north of the entrance towards the Taunoa entrance. We found on 

 the outer face of the reef slope living corals to within the range of the 

 breakers, up to the very crest of the rim of the reef flat ; these corals 

 extend, however, only to four or six fathoms, or slightly deeper occasionally, 

 the lower part of the slope being covered with broken fragments of dead 

 corals, or dead corals down to a depth of eighteen fathoms. Here and 

 there small patches of living corals extended below the thriving belt to nine or 

 ten fathoms. The principal genera were Pocillipores, Madrepores, Porites, 

 Pavonia, some of them brilliantly colored, but none very large ; the majority 

 of the specimens being small, those of larger dimensions being quite uncom- 

 mon. At about fifteen to sixteen fathoms the masses of dead corals were 

 separated by wide bare lanes of sand, with here and there larger masses, 

 from two to four feet, on the face of the slope. 



We were also greatly struck here, as later in the Paumotus, with the 

 absence of Gorgonians and of other Alcyonaria. On the sea face of the edge 

 of the narrow and comparatively bare reef flat Pocillipores were growing 

 abundantly, and fragments and masses were constantly broken off from the 

 outer edge to form a sort of shingle on the outer reef slope, greatly to 



' Dana, Coral Reefs, p. 149. 



2 Challenger Narrative of Voyage, Vol. I. Part II. p. 777. 



