138 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY. 
small area of that once covered by 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 Reef (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 crest 
of the former was probably near the eastern edge, while the highest point 
of Wakaya was perhaps nearest the western side of the original 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 Rambe 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 Ngau (Plate 13) the highest land lies 
to the east, in Nairai (Plate 14) somewhat nearer the centre, in Moala 
in the northern part of the 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.” 
