STRUCTURE OF CORAL REEFS. 131 
Near the middle of the chart is the island Goro ; its shores, 
excepting the western, are bordered by a fringing reef. The 
island Angau, south of Goro, is encircled by a coral breakwa- 
ter, which on the southern and western sides runs far from the 
shores, and is a proper barrier reef, while on the eastern side, 
the same reef is attached to the coast and is a fringing reef. 
From these examples we perceive the close relation of barrier 
and fringing reefs. While a reef is sometimes quite encircling, 
in other instances it is interrupted, or wholly wanting, along 
certain shores ; and occasionally it may be confined to asingle 
point of an island. 
Above Angau lies Naira: ; although a smaller island than 
Angau, the barrier reef is of greater extent, and stretches off 
far from the shores. *To the eastward of Nairai are Vatu 
- Rera, Chichia, and Naiau, other examples of islands fringed 
around with narrow reefs. Lakemba, a little more to the 
southward, is also encircled with coral ; but on the east side 
the reef is a distant barrier. In Azva, immediately south of 
Lakemba, the same structure is exemplified; but the coral 
ring is singularly large for the little spots of land it encloses. 
The Argo Reef, east of Lakemba, is a still larger barrier, en- 
circling two points of rock called Bacon’s Isles. It is actually 
a large lagoon island, twenty miles long, with some coral islets 
in the lagoon, and two of basaltic constitution, of which the 
largest is only a mile in diameter. Aiva and Lakemba are in 
fact other lagoon islands, in which the rocky islands of the in- 
terior bear a larger proportion to the whole area. The same 
view is further illustrated by comparing the Argo reef with 
Nairai, Angau, or Moala: these cases differ only in the great- 
er or less distance of the reef from the shores and the extent 
of the enclosed land. 
« Passing to the large islands Vanua Levu and Viti Levu, 
