306 A NATURALIST ON THE "CHALLENGER." 



At Kandavu I had an opportunity of visiting the outer 

 margin of a barrier reef. It was one of the reefs stretching 

 across the mouth of JSTgaloa Bay. As such a reef is approached 

 from behind in a boat, and viewed from sea level, nothing is 

 visible of the reef itself at a distance but a line of small 

 detached masses of rock which appear here and there, standing 

 out dark against the horizon. As the waves approach suc- 

 cessively the different portions of the reef, their crests are seen 

 rising dark above the reef-line. Then as the waves break 

 against the margin of the reef, the isolated rock-masses show 

 out in relief against the white background of foam. 



As the reef is approached more closely, the water becomes 

 shallower, and assumes a yellow tinge, caused by the light 

 reflected from the growing corals. The boat now requires to be 

 steered with care along a zigzag path between coral patches, and 

 at last grates on the growing coral as the water shallows rapidly 

 towards the margin of the reef, and it becomes necessary to 

 wade in order to proceed further. 



It is in the shallow sheltered water, inside the actual edge 

 of the barrier, that the finest and best grown specimens of the 

 corals are to be found. The tufts, bushes, and rounded masses of 

 the various corals are to be seen growing here in abundance, 

 but yet scattered over the area, with plenty of more or less 

 barren interspaces in the " coral plantation," as Dana terms it. 

 The various forms of the spongy tissued Madreporas, are the 

 characteristic feature in these Fijian reefs, there being no less 

 than 26 species of Madrepora known from Fiji. 



The outer margin of the reef is raised above the level of the 

 coral plantation in the still waters within, and the water on it 

 is thus very shallow at low tide, and often the margin is laid 

 dry. At Ngaloa Bay the barrier reef springs from the fringing 

 reef, running out from the coast across the mouth of the bay. 

 Its elevated margin was not more than 20 to 30 yards wide. 

 There is an elevated strip of about this width stretching all along 

 the reef; its surface is remarkably even, and but few stunted 

 corals were growing upon it, but Alcyonarians were abundant, 

 and the whole surface was covered with a crust of calcareous 

 seaweeds (Corallinacece). 



