Nature . ous pointsto the west. A fairly continuous reef lies along its eastside, but there is no reef off its north and south points, andreefs only occur in the bays of its western side. Silhouetteis a round island with practically no reef, while Praslinhas reefs in its bays alone. La Digne, Curieuse, and thesmaller islands have merely patches of reef. On examin-ing into the causes of this we found a luxuriance of coralgrowth even off the points of the islands, but practicallya complete absence of nullipores. Indeed, these calcareousalgae are essential in the Indian Ocean for the consolidatio
Nature . ous pointsto the west. A fairly continuous reef lies along its eastside, but there is no reef off its north and south points, andreefs only occur in the bays of its western side. Silhouetteis a round island with practically no reef, while Praslinhas reefs in its bays alone. La Digne, Curieuse, and thesmaller islands have merely patches of reef. On examin-ing into the causes of this we found a luxuriance of coralgrowth even off the points of the islands, but practicallya complete absence of nullipores. Indeed, these calcareousalgae are essential in the Indian Ocean for the consolidationof corals into true reefs. Where fringing Hats actually dooccur, they would appear generally to consist of a basis January 25, 1906J NA TURE 295 of granitic rock with quite a sparse covering of calcareousmatter, or to be a filling in with the remains of some ofthe reef organisms between masses or islets of graniteand the land. The reef in the large bay to the north of use I. <f C335, Feiicite/^ «J? ^. -Islands of the Seychelles Gr Praslin, extending along the coast for ih miles betweentwo points, is a good instance of this, one islet and threeseries of granite masses lying at almost equal intervalsimbedded in its seaward edge. The boat passages throughthe reefs are in most situ-ations mere outfalls for thetide, and show no connec-tion with the fresh-waterstreams off the land. Finally,it is interesting to note thatthe actual surfaces of theflats are covered with a fargreater variety of large sea-weeds than we found in anyof the purely coral groupswe visited in the , The land animals neces-sarily to a large extent de-pend on the plants, and Iconsidered it inadvisable toattempt their complete col-lection in the limited timeat our disposal save in theindigenous jungle. Smallmangrove swamps occur onthe sea-shore, but behindthese the land has beenalmost completely clearedfor the cultivation of cotton,coffee, cassava, cocoa, andvanilla to a height of 1500feet. Below this
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