1898.] Funafuti, Rotuma and Fiji. 427 



by these nullipores. Generally the horizontal thickness of the 

 lime formed by each plant, as it were, does not seem to be very 

 great while the total mass is enormous ; the thickness of the lime 

 of some large massive nullipores, obtained by the use of Priest- 

 man's grab outside the reef, was between 3 and 4 inches, but 

 from the reef itself I never saw a nullipore with a greater thick- 

 ness than 2 inches. What I have termed before the rim of the 

 reef is really then an area 3 — 4 feet broad at the sides of these 

 fissures, but facing the sea about 5 yards across. The waves 

 break a short distance outside the rim and rush over it, or to 

 some extent wet it every time they break ; the water also rushes 

 up the fissures, and so great is the momentum behind it, that 

 it wells over their sides in every direction. The rim generally 

 extends back all round the fissures, but from the ends of some, 

 which run especially deeply into the reef, it is absent, these 

 serving to take the return water, which is poured over the edges 

 of the others, back to the sea. 



Between these several fissures, and between the rim and the 

 rough zone under the hurricane beach, the reef-flat, before 

 mentioned, lies. The surface of this zone is very flat and smooth 

 and covered over completely in its outer parts by nullipores and 

 other algae. Its level is such that at ordinary low tide the greater 

 part of its surface is covered over by 8 inches to a foot of water : 

 its level below the rim round even the most open fissures is 

 also such that at the lowest spring tides most parts of it are 

 concealed by a few inches. Nullipores do not thrive on it well, 

 perhaps on account of the hot sun at low tide, and most of it is 

 covered by small, delicate, filamentous algae, which give it a very 

 smooth slippery surface. Holes in it a few inches to several feet 

 below its general level occur, and in these and on its outer part a 

 few species of corals are sparingly found. Of these Pocillopora 

 and Stylophora are by far the most numerously represented, and 

 in many parts were the only corals obtained from this area. 

 The species of these genera represented were Pocillopora suf- 

 fruticosa, P. brevicornis, P. clavaria, P. squarrosa, P. meandrina, 

 P. glomerata, Stylophora palmata, 8. pistillata, S. digitata and 

 three species which I have named S. compressa, S. lobosa and 

 S. rugosa. These grow for the most part in clumps, and in this 

 situation are rarely more than 6 — 7 inches in diameter, while 

 3 — 4 inches with a height of 1 — 2 inches for the clump is more 

 usual. Their distribution nowhere is such that they could for a 

 moment be considered to have any effect practically on the 

 growth of this part of the reef. The only other species of coral 

 at all common was a Prionastraea, which was however very local in 

 its distribution. 



The fissures for the reef present the most abundant signs of 



