26 "ALBATROSS" TROPICAL PACIFIC EXPEDITION. 



of the lagoon of Rangiroa. a distance of nearly twelve miles, into 897 

 fathoms (Fig. 3) ; this seems to be the depth of the western part of the 

 Paumotu plateau. 



Between Rangiroa and Tikahau, the next atoll to the westward, we 

 obtained a depth of 664 fathoms. 



Between Tikahau and Matahiva si.K soundings were made, with a depth 

 of 488 fathoms half a mile from shore, and a greatest depth of 850 fathoms 

 six and a half miles from Tikahau. The slope approaching Matahiva is 

 steeper than the Tikahau slope (Fig- 5). 



From Matahiva to Makatea (Aurora) Island, we made six soundings: 

 from 624 fathoms about two and a half miles off shore to 581 fathoms about 

 one and one-eighth miles off the west side of the latter island, the depths 

 jjassing to 860, 1257, 1762, and the greatest depth being 2267 fathoms, then 

 2247, and rising more rapidly near Makatea to 581 fathoms (PI. 201). 



Between Makatea and Tahiti we made eight soundings, beginning with 

 1363 fathoms, two miles off the southern end of Makatea, passing to 2238, 

 2363 (the greatest depth on that line), to 2224, 1930, 1585, 775, and finally 

 867 fathoms off Point Venus (Fig. 7). 



The soundings from Makatea to Niau (PI. 201 and Fig. 8) indicate that 

 Makatea is an isolated peak rising from great depths and separated from the 

 Paumotu plateau, as we find 2238 fathoms in the direction of Tahiti, 2268 

 fathoms in the direction of the Niau plateau, and 2267 fathoms towards 

 Matahiva. 



A line from Niau to the north of Apataki gave ns a greatest depth of 

 677 fathoms between Niau and the southern face of Apataki, while to the 

 north of Apataki the Paumotu plateau drops o£E rapidly to over 1300 

 fathoms (Fig. 8). 



Judging from the soundings to the east of the line from Niau to Apataki, 

 on the eastern extension of the Paumotu plateau are probably situated 

 Fakarava, Kauehi (Fig. 4), Tahanea, Makemo, and Taenga (Fig. 6). Auaa 

 stands upon an isolated ridge separated by over 1700 fathoms from 

 Tahanea, and by 1531 from Fakarava (Figs. 4, 9); Raroia and Takume 

 rise from the same plateau (Fig. 6), but are separated from the eastern part 

 of the Paumotu plateau (Taenga) by more than 1500 fathoms. 



