46 J. STANLEY GARDINER. 



mass of rock and not a sand formation. Its surface is muddy, slimy and worn into holes 

 more or less filled with sand; it is bare and smooth for the greater part, and boulders 

 are practically non-existent. The whole area is singularly devoid of animal or plant life, 

 sessile or free. A few species of coral grow at the very edge, but on the surface I only 

 found a few small colonies of Porites arenosa ; delicately branching nullipores may exist and 

 also Halimeda, but weed is generally scarce. 



The sand-flat at the south of the main island extends up round the reef to the west 

 and north, covering about half the total area of the lagoon. The whole, except a small part 

 near the lighthouse, is completely covered even at low-tide springs, the gieater part having 2 

 to o feet of water. Around the .sand-flat, wherever the reef exists, an outer zone, 100 to 1.50 

 yards broad, may be separated, characterised by its abundant growth of corals, the rest of the 

 sand being absolutely bare. The slope from the reef to the general level of the flat occurs 

 entirely in this area. The principal coral is a species of Madrepora with massive branches, 

 which is everywhere abundant in this situation. Other more delicate Madrepores occur as 

 well, mostly in isolated colonies, but a stag-horn species with branches up to 1 inch in 

 diameter forms in places close to the boulder zone regular groves. Porites arenosa is found 

 everywhere, in masses up to 20 feet across, dead in the centre, but living at the edge, 

 and places where the currents are not greatly felt are often almost completely covered 

 by it ; the masses are always free, their stalks having been destroyed, and are very 

 generally somewhat hollowed out in the centre. Pavonia repens crops up anywhere, while 

 the species of PociUopora, of which there appear to be several, are found only opposite 

 breaks in the boulder zone. Locally extremely common, especially near the western and 

 northern reefs, are great masses of Millepora, Heliopora and Psammocora, while colonies 

 of Goniastraea, Astraea, Orhicella, Prionastraea, Siderastraea, Mussa and Euphyllia are often 

 met with, frequently growing in the hollow masses of Porites arenosa. On the under- 

 surfaces of any of the above Agaricia may grow, and various species of Fungia are very 

 abundant on the bare sand. Halimeda abounds, growing among the basal branches of 

 Madrepora , but other algae can scarcely be said to occur. A mere glance at the above 

 list of the more important genera serves to show the richness of the area, and the bold 

 growth of the colonies themselves proves that the position on the whole is one eminently 

 favourable to them. The parts poorest in corals lie immediately behind the boulder zone, 

 where it is especially high or low, the stillness of the water and the too rapid currents 

 both being unfavourable. Surveyed from a boat at high tide the presence of breaks in 

 the boulder zone can be assuredly told by the white, sandy bottom continuing up to it. 

 Over the richer areas at the sides of these, heavy boots and putties are required, as one 

 literally breaks one's way through groves of coral. The skeletons of living corals {i.e. covered 

 by the living polyps) from the area are singularly free from destructive organisms of all 

 sorts, no Polychaets nor Sipunculids ; even sponges, which pervade the hard parts of most 

 or all reef corals, do not exercise much sway. The growth is hence probably extremely 

 rapid, and yet the decay must be as quick. The area is certainly not increasing in height. 

 Dead corals are found bored through and through ; they soon rot away, and break down 

 into sand, or are dissolved. 



The reef of the boulder zone can at its edge be very distinctly traced under the sand, 

 which varies between that of the former zone and the fine mud of the centre of the atoll. 



