428 Mr Gardiner, The Coral Reefy of [Mar. 7, 



coral life ; their sides, where they do not overhang excessively, 

 often have growths of Pocillopora grandis which markedly shows 

 positive heliotropism, growing outwards at first from the sides and 

 then straight towards the light. Their bottoms in any parts, 

 where they are raised above the general level, and so are above 

 the scour of the sand, may be covered with corals. From this 

 position I obtained, as well as various species of Pocillopora, two 

 species each of Goeloria and Favia and one species each of 

 Prionastraea, Heliastraea, and Montipora ; in addition to the 

 above, I also obtained Madrepora surcidosa and Madrepora haimei 

 from the north end of the main island, but did not find any other 

 species of this genus on the windward side of the atoll, although 

 in Fiji I subsequently found it to be by far the most abundantly 

 represented on the outer reefs. It would be a misnomer to speak 

 of any of these corals as being abundant on the outer reef, the 

 conditions requisite in the fissures being by no means common : 

 in any area to be visited there could only be anticipated with any 

 certainty a few species of Pocillopora and Stylophora and Mon- 

 tipora incognita (Bernard). Millepora, which is generally supposed 

 to grow where the break of the waves is strongest, I only obtained 

 in this area in a well -protected situation on the leeward side 

 of the atoll. Under the overhanging sides of the fissures corals 

 do not grow, though the conditions as to food supply should be 

 eminently favourable ; this may be due to the scour of the water 

 along the sides, but I think it may also be partially accounted for 

 by the absence of direct sunlight, the growth in general of the 

 species of Madreporaria found in these seas showing, according to 

 my observations, markedly positive heliotropism. 



The lagoon shores of the islands on the rim of the atoll have 

 either a hard pebbly beach corresponding in position, though not 

 in height or extent, to the hurricane beach with a platform 

 running off from it into the lagoon, or else a sandy beach usually 

 tailing off with a similar lagoon platform, or reef. Opposite to 

 the village there is no such reef, but the sand beach slopes off 

 gradually into the lagoon, the bottom of which is here covered 

 by a dense coating of sand. Professor Sollas, in his report 1 to 

 the Royal Society, especially draws attention to the sand : " As 

 regards the nature of this sand it is important to observe, that it 

 does not consist of coral debris ; this material and fragments of 

 shells forming but an insignificant part of it ; calcareous algae are 

 more abundant, but its chief constituents are large Foraminifera, 

 which seem to belong chiefly to two genera (Orbitolites and 

 Tinoporus). It covers a considerable area of the islands, and has 

 accumulated during the memory of the inhabitants to such an 



1 hoc. cit. p. 375. 



