DammermaN: Fauna of the Kfcikatan Islands. 87 



the strong fliers which occasionally arrive and do not find the island a 

 good habitat, will probably migrate further, but the sluggish species, having 

 been carried unintentionally to their new home, are by no means so easily 

 off again. 



Also, 1 believe, ships are playing a more important part in the dispersal 

 of animals than is generally admitted. Many insects and other winged 

 animals rest on, or follow, ships for a short time. When a ship is at anchor 

 in a harbour or in a bay there are always some animals coming aboard, 

 especially at night when they are attracted by the lamps. Sailing out to 

 sea the ship will probably carry along some of these species. Most of them 

 disappear again after a few hours but by this time, being already some 

 miles from the coast, they fly to islands in the vicinity if these are nearer 

 than the mainland. Now in Sunda-Strait there is always a constant traffic, 

 not only of big steamers but also of many native vessels as well, in the 

 direction north-south, east-west and vice versa. This traffic must not be 

 neglected as a factor in the reoccupation of Krakatau by a new fauna. 



That in 1Q08 aquatic insects, or insects the larvae of which live in 

 fresh water, were nearly wholly absent, is, I suppose, not due to the fact 

 that such larvae cannot be dispersed by sea, but can be put down to the 

 proper conditions for the existence of these animals not being present. 

 The rather rich insect fauna of the lake on Verlaten I. North having been 

 invaded in a few years only, just proves, 1 think, that in the first place 

 the islands are reached by winged adults. 



. A special investigation with regard to the different means of dispersal of 

 animals is planned by the author, and it is hoped that by future researches 

 it will be settled how far the above suggestions are right. 



Also the problem has to be investigated as to how long different animals 

 (adults as well as their different stadia) can stand drifting on sea? 



in this connection we may mention here the experiments made by 

 Leefmans (see his above quoted paper). He found that Oryctes-hrwat, 

 bored in wood, could stand immersion in seawater for 24 hours. By this 

 time even drifting wood can easily cover the distance from the Java coast 

 to Krakatau, the ocean currents in Sunda-Strait being very fast. 



IV. Arc there already local forms originated on the islands? 



Theoretically Krakatau and Verlaten Island, perhaps also Sebesy, could 

 give rise to new local or insular forms, as so many are already known 

 to exist on other islands of the Malay Archipelago. 



Now if one finds a new species or a new aberrant form on one of these 

 devastated islands, it would be unwise to pretend that this form must have 

 originated on the spot. In all probability the same form will inhabit other islands 

 in the vicinity or the adjacent mainland; it only has not yet been collected 

 there, in this connection we may repeat that especially our knowledge of the 

 fauna of the islands in Sunda-Strait and of the land surrounding it, is scanty. 



