APPENDIX 



453 



brought by drifting logs or attached to the feet of sea-birds : Cyperus 

 brunneus, Dondia linearis, Iva imbricata, Sesuvium portulacastrum. 



(F) Plants, like Uniola paniculata and Andropogon glomeratus, 

 that may have been brought, as Millspaugh suggests, by currents 

 (Uniola), or through the agency of birds (Andropogon), but concerning 

 which observation is needed. 



Only the most characteristic plants are here dealt with. Quite 

 half of the twenty-three plants above named would owe their pres- 

 ence on the Florida sand-keys to the direct agency of currents. In 

 the case of a quarter, the agency of the drifting log could be appealed 

 to. Though one may be too much inclined to fall back on the 

 drifting log in cases of difficulty, its intervention is much more than 

 a mere possibility. On Keeling Atoll I found a stranded log honey- 

 combed by the Teredo, the empty burrows of which were filled by 

 sand, with which many of the small pyrenes of Tourneforfia argentea 

 and other small seeds were mixed. With a high tide and a heavy 

 sea this log could have been swept off the beach and carried seaward. 

 Birds might have aided in the case of the remainder. Frugivorous 

 birds probably played a small part, since, if we except Sccercola 

 plumieri, but few of the plants would possess fruits that would 

 attract them. However, the plant just named was more probably 

 brought by currents. But one or two of the plants not named in 

 the list, such as Ernodea litoralis, might have been brought here in 

 this way. Dr. Millspaugh informed me that the seeds of Euphorbia 

 buxifolia become adhesive when moistened. So it has been placed 

 in the group with Cenchrus tribuloides. The attachment of the 

 prickly fruits of Cenchrus to one's clothes will be familiar to all who 

 have sojourned in the tropics, one of the American names of the 

 species above named being " claw-grass." 



Of the plants in the first group some would be dispersed through 

 the floating seedling, as in the case of the species of Rhizophora and 

 Azicennia. and also of Bat is and Salicornia, though with the last two 

 plants the seeds (Batis) and the detached seed-bearing joints (Sali- 

 cornia) possess independent buoyancy. The dispersal by currents 

 of Salicornia peruviana, S. herbacea, Batis marituna, etc., is dealt 

 with in my work on Plant Dispersal. 



Note 7b (p. 5). 



A comparison of the vegetation of sand-islets in the coral-reef regions 

 of the West Indies, and of the Pacific and Indian Oceans. 



For this purpose the results of Mr. Lansing's observations on the 

 Florida sand-keys will be utilised, as given in Dr. Millspaugh' s 

 paper. Although the present writer has no acquaintance with the 

 Florida sand-keys, he formed a close acquaintance with nearly all 

 their characteristic plants on the shores of the Turks Islands. On 

 Keeling Atoll and on North Keeling Island, on the south coasts of 

 Java, in the Solomon Islands, and in Fiji, he became familiar with 



