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APPENDIX 



the plants with which currents and birds stock the newly formed 

 islets thrown up on the reefs of those seas. His first study in the 

 plant- stocking process of such islets was made in the Solomon 

 Islands in 1882-3, the particulars of which are given in his work on 

 those islands and in the Appendix of Mr. Hemsley's volume on the 

 botany of the Challenger expedition. Although the following remarks 

 mainly apply to the region of the Western Pacific, it might in most 

 respects apply to islets in the Indian Ocean, such as are presented on 

 Keeling Atoll and in the small island of North Keeling to the north 

 of it, many of the plants being the same. 



There are some points of similarity as well as great points of con- 

 trast between the vegetation of reef-islets in the Western Pacific and 

 in the Florida seas. In appearance there is a great contrast, since 

 the large trees, often with handsome flowers and large fruits (Barring- 

 tonia speciosa, Calophyllum inophyllum, Cerbera odollam, Guettarda 

 speciosa, Hernandia peltata, Ochrosia, Pandanus, etc.), that line the 

 beach in a Pacific islet are not to be found on islets in West Indian 

 waters, where the vegetation bordering the beach is formed of shrubs 

 and small trees of a very different character. Then, again, we miss 

 in the Florida sand-keys the tall trees of Canarium, Eugenia, and 

 Ficus (banyans) that occur in the interior of islets in the Western 

 Pacific — islets only a few hundred yards in length and heaped up but 

 two or three feet above the waves. These trees represent the work 

 of the fruit-pigeons, an agency ever in operation in these seas. 



The similarity is greatest in the case of the plants creeping on the 

 sand, and with the shrubs and small trees with their climbers that 

 form the outposts of the beach vegetation. Canavalia obtusifolia, 

 Ipomoea pes-caprce, Sesuvium portulacastrum, and Suriana maritima 

 occur alike on the Florida sand-keys and on the coral islets of the 

 Indian and Pacific Oceans. But representative species of the same 

 genus may play the same role in the different regions. On the 

 Florida sand-keys and in the Turks Islands bushes of Sccevola plumieri 

 and Tournefortia gnaphalodes give the same character to the sand- 

 dunes bordering the beach that is displayed by Scazvola koenigii and 

 Tournefortia argentea on Keeling Atoll and in the islets of the Western 

 Pacific. 



The differences also extend to the composition of the mangrove 

 colonies formed on the lee side of the islets. Of the three mangroves, 

 Rhizophora mangle, Avicennia nitida, and Laguncularia racemosa, on 

 a Florida sand-key, only the first might be found in the Pacific islet, 

 though its place would more probably be taken by the Asiatic species, 

 Rhizophora mucronata. The species of Laguncularia would be repre- 

 sented in the Pacific by a species of Lumnitzera, an allied genus. The 

 genus Avicennia would not be present. 



If we except the agency of the fruit-pigeon in the Western Pacific, 

 the currents would seem to be more effective in that region than in 

 the Florida seas. Practically all the large trees lining the beach in 

 the Pacific islets owe their presence there to the currents, whilst the 

 fruit-pigeon has stocked the interior. 



