MANGA EEVA. 65 



The islets and the islands of Aka-Maru, Mekiro, and Maka-pu are within 

 a fringinsa; reef fiat wliicli runs around tlie west and nortliern faces of Aka- 

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

 of more tlian lialf a mile in a nortlieasterly direction almost to the outer 

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

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

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

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

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

 fourths fathoms of water on tliese 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 j^erhaps further indicated by the comparatively 

 shallow Hat of the lagoon, dotted with reef patches, to the west of the 

 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 

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

 Vai (PL 65), Au Kena (PL 66, figs. 1, ;?), and Aka-Maru (PL 67). Tara-Vai 

 is flanked by Aga-kanitai and another islet to tlie west called Tep(ju-nui ; 

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

 south. The southwest face of Aka-Maru (PL 67, fig. l) is an 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 the 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-Yai. The lagoon seems to form a western basin 

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

 the east of Au Kena and Aka-Maru. Ijing 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 



