1891.] D. Prain— r/ie Vegetation of the Coco Group. 379 



only to the Pacific from the Indian Ocean, another only to the Atlantic 

 from the Indian Ocean. The Gymodocea, though present in Africa, 

 appears not to be recorded from the Mascareiie Islands, and Sargassum 

 ilicifolium though occurring in Malayan waters, has not yet been found 

 on the coasts of Northern Australia. One species, Bictyota dichotoma, 

 is rather more frequent in sub-tropical than in tropical seas and is 

 cosmopolitan in both the northern and the southern hemispheres. 



The next group of species to be considered — the " littoral " — in- 

 cludes many plants for which the evidence of inti'oduction by the sea is 

 almost as palpable as in the case of the " marine " species themselves. 

 They germinate on the beaches, and grow only near the sea, preferably 

 in muddy creeks or on the sand or shingle ; their fruits and seeds are 

 found in every " drift " and the species themselves occur on every Indian 

 or Malayan coast. Such are the true mangroves and the species like 

 Avicennia, ^giceras, Garapa, that are constantly associated with the 

 mangrove-vegetation ; the sand-binding species like Ipomosa biloha, 

 Euphorbia Atoto, Sesuvium Porttdacasfrum, Vigna lutea, Thuarea sar- 

 mentosa ; the tropical seSb-ience oi Pandanus odoratissimiis, Desmodmm 

 umbellatum, Sophora tomentosa, Tournefortia argentea, Glerodendron 

 inerme, Vitex Negundo, with its concomitant climbing vegetation, Gana- 

 valia obtusifoUa, Ipomoea digitata, Argyreia tilicefolia ; the outer beach- 

 forest of Terminalla Gatappa, Hernandia peltata, Erythrina indica, 

 Stephegyne diversifolia ; the inner beach forest of Gycas, Mimusops and 

 Pisonia ; and even the species of the mud-flats within, like Z/eea sa?n- 

 bucina, Hibiscus tiliaceuSf Gynometra ramifiora, Flagellaria indica and 

 many more. The seeds of all these have been observed by the writer 

 in the " drifts " of these islands and many of them have been noted, either 

 in the Andamans and Mcobars, or in N'arcondam, germinating on the 

 beach. There are others, however, that are more doubtful, and, though 

 the whole of the species for which this mode of introduction is con- 

 ceivable are given below, the species for which any doubt is possible are 

 enclosed in brackets and the more equivocal of these are discussed at 

 the end of the list.* 



* Since this paper was written and while these pages have been passing through 

 the press two papers have appeared that deal with this section of the flora of the 

 Malayan countries much more fully than the scope of the present paper permits. 

 To these papers, viz : — Schimper : Die Indo-Malayische Strandflora (Jena : Gustav 

 Fischer, 1891) and Karsten : Ueher die Mangrove-Vegetation in Malayischen Archipel ; 

 Bihliotheca Botanica, Heft 22 (Cassel : Theodor Fischer, 1891) neither of which had 

 appeared when the writer's remarks were written and which he greatly regrets having 

 been unable to refer to in the text, the writer would refer those who are interested 

 in the subject of mangrove and coast plants and the influence of ocean-currents and 

 their distribution. 



49 



