Agassiz — Albatross Expedition to the Eastern Pacific. 369 



The western bays of Manga Reva Island are filled with 

 fringing reefs which leave but here and there a deeper pass 

 to the shore. The south face at the foot of the bluff of Mt. 

 Mokoto and Mt. Duff is edged by a flourishing fringing reef, 

 which extends nearly half a mile on the plateau at their base. 

 The port of Rikitea is a reef harbor formed within the large 

 fringing reef which occupies the whole of the southern bay of 

 Manga Reva Island. The east face of Tara Vai and part of 

 the east and of the west face of Aga-kanitai are also fringed 

 with reefs. 



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

 are within a fringing reef flat which runs around the west face 

 of Aka Mara ; Au Kena is also fringed by an extensive reef 

 which runs out in a spit of more than half a mile in a north- 

 easterly direction almost to the outer line of mot us, which are 

 nearly united with it by these irregular patches. To the west 

 of Au Kena a huge spit of 2 miles in length extends towards 

 the base of Mt. Duff 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 1 to 2f fathoms of water on these two spits. 



The depth of the basin within this area with from 25 to 31 

 fathoms would be naturally 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 to the west of the barrier reef, with from 5 to 11 

 fathoms of water. 



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

 the lagoon. The four larger islands are Manga Reva, Tara 

 Vai, Au Ivena and Aka Maru. Tara Yai is flanked by Aga- 

 kanitai and another islet to the west called Topunui ; Aka 

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

 the south. The southeast face of Aka Maru is an extinct 

 crater, of which Maka-pu forms the south rim. The main 

 ridge of Tara Yai is the edge of parts of three craters now 

 opening to the west. The four small volcanic islands in the 

 southern part of the lagoon are isolated fragments, steep to, 

 greatly weathered, and disintegrated. 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. 



