58 Means of Dispersal 



selection, the destruction by animals of certain seeds and fruits among 

 the drift-material, especially by hermit and other crabs, as Schimper 1 

 and Guppy 2 have described in the case of other coasts, does not 

 appear to have been operative in this instance. The small hermit- 

 crabs which live in gasteropod shells, the busy peregrinations of 

 which I have had an opportunity of noticing on the beach of 

 Sumbawa and Noesa Kambangan, are not found on Krakatau or on 

 Verlaten island. There appears to be no evidence of the occurrence 

 of crabs such as Guppy has described as subsisting chiefly on the drift- 

 fruits and seeds on the beach of the Cocos islands, though the name 

 "Crab Island" formerly applied to Krakatau suggests their former 

 occurrence. Out of fifty to sixty living seedlings of different species of 

 strand-plants met with in the drift in the Cocos islands only about a 

 dozen species escaped destruction by crabs, with the result that, despite 

 the richness of the drift-material, a strand-flora containing only a 

 small number of species was produced. On Krakatau a number of 

 plants have succeeded which belong to species the fruit, seeds and 

 seedlings of which are most eagerly sought after by crabs : for example 

 Cerbera Odollam, Calophyllum, Carapa, Cocos nucifera. The large 

 number of coconut palms on Krakatau is an especially remarkable 

 feature. Statements occur in the literature 3 to the effect that coconuts 

 from drift-material seldom germinate ; moreover in many places empty 

 nuts only occur in the drift-zone. These nuts have not all been opened 

 by crabs ; the presence of a circular opening, from 1 to 2 cm. in diameter, 

 on many of them shows that the fruits were eaten by squirrels, which 

 are common in the Archipelago, before their transport in the water. 



2. Seed-dispersal by birds. 



In addition to transport by water some of the strand-plants of 

 Krakatau may have been introduced by birds. According to Guppy 

 the seeds of Pemphis aeidula adhere freely to the feathers of birds 

 which build in the bushes of the coast vegetation or obtain nesting 

 material from them ; in many instances the seeds of Krakatau plants 

 may have been introduced in the bodies of birds. 



The following plants included in the Krakatau list, Ximenia 

 americana, Eugenia, Premna, Cassytlia filiformis, are among those 

 mentioned by Hemsley as having been found by Guppy and Moseley 4 

 in an uninjured condition in the crops and intestines of fruit-eating 

 birds. Schimper considers that Morinda eitrifolia and Scaevola 



1 Schimper, A. F. W. Indomalayische Strandflora, p. 75. 



2 Guppy, H. B., loc. cit. p. 11. 



3 Engler, A. Entwicklangsgeschkhte der Pflanzenwelt, n. p. 183. 



4 Hemsley, W. B., loc. cit. Challenger Reports, Botany, Vol. i. pp. 43, 44. 



