68 BULLETIN: MUSEUM OF COMPAEATIYE ZOOLOGY. 



varyiug iu width from a few yards to 300 or 500 yards, or even disap- 

 pearing entirely along some of the beaches, with many areas of smooth 

 impounded water within the fringing reef flats. The north side of the 

 lagoon is protected by an outer reef flat fully half a mile wide in some 

 places. On it corals are flourishing. There are two passages into the 

 lagoon, with about ten feet of water in the channel. On the eastern 

 side the outer reef runs parallel with the coast, gradually becoming "wider 

 towards the south, where it forms a wide coral flat connecting as a frin- 

 ging reef the outer reef with the low southern part of the island. 



To the west of the lee passage are the small island of Yatu Savu 

 (Plate 101), consisting of a larger low rock of elevated limestone deeply 

 undercut and pitted and honeycombed, and of three other mushroom- 

 shaped rocks of the same structure. Between the lee and the weather 

 passage are the islands of Yatu Levu and the cluster of rocks Yatu 

 lai lai (Plate 102), similar in structure and in appearance to Yatu Savu. 

 These islands and islets are all situated upon the flat of the outer reef. 

 The whole reef flat is further studded with negro-heads, the remnants of 

 former islands and islets of elevated limestone. 



The presence of these islands, islets, and rocks, as well as the existence 

 of the extensive flats ofi" the east coast, clearly indicate the manner in 

 which denudation and erosion have transformed the greater Yatu Leile 

 which once may have covered the whole- area of the lagoon, leaving only 

 a part of the main island, with the islands and islets on the outer reef 

 flats and the innumerable patches of corals flanking the inner edge of the 

 outer reef. There is a strong current flowing out through the passages 

 of the northern line of the outer reef. 



THE SOUNDS OF FIJI. 



Plate 32. , 



Fulanga is also interesting as illustrating the formation of an atoll by 

 the same causes which have produced the Sounds iu the Bermudas.^ 

 In the case of Fulanga we have a ring of elevated coralliferous lime- 

 stone raised by volcanic agencies to a height of nearly two hundred feet. 

 The whole area of Fulanga was probably once covered by coralliferous 

 limestone, forming an island resembling Kambara or Mango. The island 

 was, judging from its present condition, highest on the northern side, with 



1 Bull. :Mus. Comp. Zool., Vol. XXVI. Xo. 2, 1895, p. 231 ; also Bull. Mus. Comp. 

 Zool., Vol. XXVIII. Xo. 2, 1896, p. 29. 



