DESCRIPTION OF THE EXPEDITION. 139 
The west reef, where it exists, has a yet gentler slope than the eastern, on account of 
the shoaling of the lagoon. It is almost bare of grass, and hence supports more coral, 
though there is practically no Heliopora. Its edge, boulder-zone, and shore-flat are 
more marked ; and the island behind shows in places rather more loss, as is evidenced 
by many fallen coconuts and other trees. 
Not until the collections have been worked out can we give any adequate idea of the 
fauna and flora of the reef. Most animals were obtained by turning over the corals, and 
all groups seemed to be more abundant in species than in the Chagos, the Holothuria 
being perhaps an exception. In Turbellaria and Nudibranchs this great superiority was 
most noticeable, and even in corals, which we did not attempt to collect, it appeared 
richer. The dominant species of Sarcophyta, white in the breakers of the east side and 
purple in those of the west, with yellow incrusting species behind, were not the same as 
the Chagos forms; and wide differences were noticeable in other groups of animals. 
Indeed the Chagos resembled the more barren Maldivian reefs, while here there seemed 
to be a new type of reef altogether. Of course this is partially due to the Cymodocea, 
but there is much more green algal growth generally. 
The land is entirely formed either of loose sand or of sandstone (tuffe). Until the 
specimens are examined carefully, it is impossible to speak definitely of its composition ; 
but we could see no reason why it should not all have been thrown up by the waves and 
by the wind. Generally its surface is about 10 feet above the high-tide level, and when 
broken into, as is always done when making pits for coconut-planting, there is found a 
thickness of 1 to 3 feet of tuffe overlying loose sand. There is a sand-ridge round the 
east side of the island, generally about 50 yards back from the beach, but becoming 
rather irregular in the north half, where it lies more inland; it averages 15 to 40 feet 
high, and culminates at the south in a hill of about 50 feet. Round the north end it is 
also well marked, and there is in the centre of the island, halfway from the Settlement 
to that end, a larger dune of upwards of 75 feet high. Low damp areas of land of only 
5 feet above the high-tide level are found behind the north point and in two or three 
other positions; they are notable for the luxuriance of their coconut and other vegetation. 
The Settlement stands on such an area, separated from the tuffe-land behind by a pool 
of fresh water, 150 yards long by 50 yards broad, the home of many dragon-flies. 
The character of the vegetation was the same as that which we found in the Chagos 
Archipelago on similar, dry, sandy and tuffe lands. It consisted of low bush formed 
mainly of Seevola and Erythroxylon, the former with thick succulent stems and leaves 
like the laurel, and the latter with tiny leaves, yellow flowers, and stems covered with 
mossy lichens. The ground between was mainly covered with isolated plants of a low 
rush, while struggling clumps of the hairy-leaved Towrnefortia and of the thinner-leaved 
Pisonia were found here and there. Probably there were not 20 species of plants 
altogether on this kind of land, but the lower patches yielded a more considerable 
variety of species. These, when compared, turned out to be almost precisely the same 
as those obtained from the Chagos. This was to us asource of considerable astonishment, 
because, from the island being so much nearer to Africa, to Madagascar, to the Seychelles, 
and to many other islands which might serve as stopping-places from the more distant 
