MANGA REVA. 65 



The islets and the islands of Aka-lNIaru, Mekiro, and Maka-jni are within 

 a fringing reef flat which runs around the west and northern faces of Aka- 

 Maru ; Au Kena is also fringed by an extensive reef which runs out in a spit 

 of more than lialf a mile in a northeasterly direction almost to the outer 

 line of motus, whicli are nearly united with it by these irregular patches 

 (PL 14). To the west of Au Kena a huge spit of two miles in length ex- 

 tends towards the base of Mount Duif and almost unites with the fringing 

 reef off the cemetery, leaving a narrow, but deep pass for the entrance of 

 ships into the inner harbor of Rikitea. There is only one to two and three- 

 fourths fathoms of water on these two spits. 



The depth of the basin within the area, bounded by Manga Reva and 

 Au Kena and its connecting spit, with from 25 to 31 fathoms, would be nat- 

 urally explained as being part of an ancient crater, as in Totoya in Fiji ; its 

 northeastern rim is also perhaps further indicated by the comparatively 

 shallow flat of the lagoon, dotted with reef patches, to the west of tlie 

 eastern barrier reef, with from 5 to 11 fathoms of water. 



The principal islands of the group are in the central part of the lagoon 

 (PI. 14). The four larger islands are Manga Reva (Pis. 61, 62, 64), Tara- 

 Vai (PI. 65), Au Kena (PL 66, figs. 1, 2\ and Aka-Maru (PI. 67). Tara-Vai 

 is flanked by Aga-kanitai and another islet to the west called Tepou-nui ; 

 Aka-Maru is flanked by Mekiro to the north, and by Maka-pu to the 

 south. The southwest face of Aka-Maru (PL 67, fig. l) is au extinct crater, 

 of which Maka-pu (PL 67, fig. 2) forms the south rim. The main ridge of 

 Tara-Vai is the edge of parts of three craters now opening to the west 

 (PL 14). The four small volcanic islands in the southern part of the lagoon 

 are isolated fragments, steep to, greatly weathered, and disintegrated (PL 68). 

 No soundings exist to show their relation to the other islands of tlie group. 



The soundings thus far made indicate in the southern part of the lagoon 

 a depth of about 23 fathoms, with an occasional hole of from 38 to 40, 

 and a gradual slope towards the outer sunken reef. To the south of the 

 old crater of Manga Reva the general depth of the bank varies from 6 to 11 

 fathoms, with a deeper channel varying from 20 to 40 from .'southwest of 

 Au Kena towards Tara-Vai. The lagoon seems to form a western basin 

 where the deptli varies from 10 to 20 fathoms. An eastern basin runs to 

 the east of Au Kena and Aka-Maru. lying between them and the line of 

 islets on the outer encircling reef. A similar, but shallower, basin exists 

 off the northern end of Manga Reva, between it and the northern horn 



5 



