AGASSIZ: FIJI ISLANDS AND CORAL’ REEFS. 91 
flat as far as we followed it to Avea. ‘The bluffs forming the steep 
sides of the island are undercut and deeply indented, forming gorges 
and ravines (Plate 74) which cut into the island or separate dome-like 
islets from the adjacent shores. The elevated limestone is full of species 
of coral, mainly large heads of species of Astreeans, of Mzeandrinas, and 
Pocillopores, which appear to be closely allied if not identical with those 
now living. One of the points of Ngillangillah was merely a thin shell 
covering a huge cavern some 90 feet in diameter and rising to a height 
of nearly 100 feet, and fall of stalactites. The rock in the pool at its 
base was covered with Gorgonians and small corals, and abounded in 
Comatulee. 
The narrow channel lying between the north shore of the large island 
and the outer reef is full of flourishing coral patches. The many nar- 
row deep cations (Plate 74) cut into the face of the island with the 
dome-shaped or mushroom-shaped heads of elevated reef rock projecting 
a few feet above the water line give to this shore line a very picturesque 
appearance. It isasimple matter to follow the extent of the elevated 
reef rock eastward, and to trace the gradual appearance of the central 
ridge of volcanic rocks until we come to the headland north of Koro 
Mbasanga (Plate 72), where we find only a comparatively small outlier 
of the elevated limestone, and a similar one to the south of the village. 
Northeast of Koro Mbasanga lies the island of Avea (Plate 75), which 
rises to a height of 600 feet, and which is wholly composed of elevated 
limestone. ‘This island as well as Susui runs at an angle from the 
outer reef, and shows the great width of the former elevated reef. From 
Koro Mbasanga south and for some distance beyond Lomaloma the vol- 
canic rocks occupy the whole width of the island, and the elevated lime- 
stone has disappeared to reappear again on the southern spit of the main 
island, and to extend eastward in the islands of Malatta and of Susui 
and their many outliers, as heads, rocks, and islets, both on the northern 
and off the eastern point of the latter island. The island of Munia 
consists, like the central part of Vanua Mbalavu, of voleanic rocks. The 
island of Thikombia i lau, on the contrary, is composed of elevated lime- 
stone rising toa height of 550 feet. Beyond Avea lie the Sovu Rocks, 
three small islets about two miles inside the outer reef, also of elevated 
limestone, one of which rises to a height of 230 feet. Between Avea 
and the Sovu Islets runs southerly for a distance of nearly five miles a 
series of narrow coral patches, which, so far as I can judge, are rem- 
nants of the ancient elevated limestones, as are probably the heads and 
patches of the eastern part of the lagoon beyond the Tongan Pass. On 
