138 BULLETIN : MUSEUM OF COMPAKATIYE ZOOLOGY. 



small area of that once covered bj the island originally occupying the 

 area of the lagoon ; this denudation having been carried to a still greater 

 extent in the Kimbombo cluster (Plate 19), in Komo (Plate 22), and 

 the islands of Duff Eeef (Plate 18). This process of denudation and 

 submarine erosion may have gone so far as to leave no trace in an atoll of 

 its volcanic or of its limestone (elevated) origin, its shape to-day being 

 entirely due to mechanical action, and having nothing to do with the 

 growth of the corals which have found a footing upon the flats due to 

 submarine erosion and to denudation and to the action of the atmosphere 

 and of the sea. 



It seems to me as if the position of an island left on the western or 

 lee edge of a lagoon depended upon the original position of its highest 

 point. This appears in the case of Makongai and Wakaya. The ci'est 

 of the former was probably near the eastern edge, while the highest point 

 of Wakaya was perhaps nearest the western side of the origi-nal island 

 (Plate 15). Similarly the highest summit and ridge of Vatu Leile, if our 

 ■views are correct (Plate 9), was on the western face of the original land 

 mass. The highest ridge of Eambe lies on the northwestern side of the 

 submarine plateau ; the islands of Budd Reef indicate its highest land to 

 have been on the northern part of the plateau (Plate 18). In Mbengha 

 (Plate 8), on the contrary, the highest land mass is found on the east 

 face of the lagoon. In the Great Astrolabe Lagoon it was in the central 

 line of the plateau (Plate 10). In Xgau (Plate 13) the highest land lies 

 to the east, in Nairai (Plate 14) somewhat nearer the centre, in Moala 

 in the northern part of tlie lagoon. In Totoya (Plate 23) the highest 

 part of the rim is the eastern edge. 



The northeastern part of Ngele Levu must have been the highest ex- 

 tremity of the Ngele Levu land mass (Plate 17). The islet at the north- 

 eastern extremity of Wailangilala (Plate 18) indicates the position of 

 the highest part of that atoll. The highest land of Naitamba, Kanathea, 

 Vanua Mbalavu, and Katavanga lies on the western part of the plateau 

 (Plate 19), and also that of Lakemba (Plate 21). 



The highest of the land masses of Aiwa, of Oneata (Plate 21), and 

 of Komo (Plate 22) was on the southern edge of these plateaus. In 

 Mothe it lay near the northern extremity (Plate 22). In Namuka and 

 Ongea it ran through the central parts of the group (Plate 22). In 

 Fulanga the land seems to have been equally high on the northern and 



to the inner channels within barrier reefs. . . . The reefs within the lagoons cor- 

 respond very exactly in mode of growth and other characters to the inner reefs 

 under the lee of a barrier." 



