378 
to introduction by means of ocean-currents. But just as we have seen 
that some of the weeds may be claimed as indigenous, or at all events as 
introduced by other than human agency, so here we find that these classes 
pass insensibly into each other and that species which may be introduced 
by the sea, such as Entada scandens, Gloriosa superha, Boerhaavia repens, 
Cocos nucifera, etc., may quite as reasonably owe their presence to a pre¬ 
vious land-connection, to wind, to birds, or to involuntary or voluntary 
human agency. The more doubtful instances, however, will be found 
discussed in detail below. This group of species, however, as a whole, 
is characterised by a general distribution which is directly affected by 
the physiographical features of, and the currents that prevail in, the 
surrounding seas, and is only indirectly, if at all, influenced by the con¬ 
figuration of the adjacent land. 
The “coast” species have to be further subdivided in “marine” 
and “ littoral ” species, and the former group, as comprising the plants 
for which the influence of ocean-currents is most evident, will be consi¬ 
dered first. Only one Phanerogam belongs to this class; this species, 
Gymodocea ciliata, is however almost the most plentiful, the only other 
common species being Sargassum ilicifolium ; all the others are very incon¬ 
spicuous, being few in number, small in size, and scantily represented. 
The following table gives at once a list of, and indicates the marine 
distribution for, these species; for six of them, as the general list shews, 
this is, as i*egards the Algce, only approximate. 
Table XIII. Distribution of the “ Marine ” species present in the Coco 
Group. 
Species. 
1 Atlantic. 1 
1 Indian Ocean. I 
1 Pacific. 1 
Species, 
Atlantic. | 
Jndian Ocean. I 
Pacific. 1 
Gymodocea ciliata 
X 
Gelidium corneum 
X 
X 
X 
Sar^assnra ilicifolium 
X 
X 
X 
Caulerpa clavifera 
X ■ 
’ X 
X 
Turbinaria ornata 
— 
X 
— 
Caulerpa plumaris 
- 
X 
— 
Padina pavonia 
X 
X 
X 
Valonia fastigiata 
— 
X 
X 
Dictyota dicliotoma 
X 
X 
X 
Valonia confervoides 
— 
X 
— 
Lithothamnion polymorphum ... 
X 
X 
-- 
Halimeda Opuntia 
X 
X 
X 
Acanthopbora Thierii 
X 
X 
X 
Sipboiiocladus ? filiformis 
— 
X 
— 
Jania tenella 
— 
X 
— 
Yaucheria sp. 
— 
X 
_ 
Gracilaria crassa 
X 
Calothi’ix pulvinata ... 
X 
X 
X 
Nearly one-half of the species are cosmopolitan in tropical seas; 
probably some of the six of which the distribution is not accurately 
ascertained are also cosmopolitan. One species appears to extend 
188 
