130 MR. A. E. FINCKH. 



walking out to the very edge at low- water spring tides. Its downward slope, however, 

 was investigated from a canoe by means of the water telescope. Such an examination 

 was, as a rule, practicable only during the monsoon season, when, the S.E. trade 

 wind having been replaced by the N.W. monsoon, this eastern part of the atoll 

 became temporarily the leeward side, so that the sea off this part of the reef platform 

 was comparatively smooth. By paddling up to within a few feet of the position on the 

 edge of the reef, which was previously examined from the shore, we saw the rock-masses 

 separating the channels slope down gently into from 3 to 5 fathoms of water. At 

 that depth these ridges unite with the troughs between them to form the general slope 

 of the atoll. There is no sign of overhanging rocks or buttresses. The loose material 

 noticed in the channels on the platform does not extend down the slope, for in front of 

 the ridges seawards it has entirely disappeared, and the reef presents a solid floor of 

 Lithothamnion rock. The surface of this rock is extremely rough and uneven, but its 

 inequalities do not interrupt the general and gradual downward slope of the atoll. 

 The lifeless appearance of the reef- rock continues in a downward direction; of coral 

 there is less than ever, and where it does occur it is in small isolated pieces. Here 

 and there are clusters of Halimeda and of small non-calcareous green seaweeds, but 

 neither are very abundant. Besides the general uneveness of the Lit! ioth amnion rock 

 there are present the innumerable small cavities already mentioned as occurring on 

 the platform, of irregular shape, mostly longish and tortuous, and invariably inhabited 

 by echinoids. Every individual of these, whether large or small, seems to lit perfectly 

 into the cavity inliabited by it, so as to suggest that tlie cavities are their work. 

 By means of the water telescope this groinid coidd be surveyed down to from 10 to 

 15 fathoms. Dredgings were not carried on in this locality, but a description is 

 given in the following su})-section of material dredged in other parts of this atoll 

 from various spots on the ocean slope of the atoll. 



(2) Comparison of the Platforms, Slopes, and Islets of Different Localities on 



the Atoll. 



The ocean platform as described near the islet of Fualopa is typical of the leeward 

 rim of the atoll; that near the 1897 boring is typical of the windward rim. 



The characteristic features of the former are : — (l) The enormous quantity of the 

 branching Lithothamnion. (2) The vivid colouration of the Lithothamnion , which is 

 here represented by all three forms. (3) The great abundance, near the edge of the 

 coral, of the small brownish species of Madrepora loripes. (4) The smallness in 

 dimensions of all species represented. No one species occupies large areas, but is 

 represented as isolated coralla surrounded by other forms. Ileliopora coivulea* and 



* As far, however, as could be judged liy means of the water telescope, a considerable amount of 

 Heliopma ccendea appeared to be growing at a depth of a few fathoms on the lagoon side of the reef between 

 Fuafatu and Fualopa.— T. E. W. D. 



