64 Treubia Vol. Ill, 1. 



Dr. SUNIER paid special attention to the brackish-water lake on Verlaten I. 

 He also brought together a small collection of land animals and discovered 

 for the first time* true earthworms on Krakatau. 



The above mentioned Congress was held at Batavia in October 1919; 

 but as the excursion to Krakatau and Verlaten I. lasted not more than one 

 day, only a few hours could be spent on both islands and there was no 

 time for much collecting. At this Congress a new and complete survey of 

 the flora and fauna of the islands was planned ;— Dr. DOCTERS VAN LEEUWEN 

 would do the flora and the author the fauna. 



My first trip of longer duration was made in December 1919 when 

 I visited Krakatau from 10—14 Dec. and Verlaten 1. from 15—17 Dec. 

 For a few days Mr. Groenewege, bacteriologist at the Department of 

 Agriculture, accompanied me, in the samples of soil he brought with him 

 to Buitenzorg he found several soil Protozoa. 



In April 1920 Mr. VAN LEEUWEN and myself again visited both 

 Krakatau and Verlaten I. ; I was on Krakatau from 23 — 26 April ; on 

 Verlaten 1. from 21—22 and the 27th April. In September 1920 Mr. SlEBERS, 

 the ornithologist of the Buitenzorg-Museum, was ray companion; we stayed 

 at Krakatau from 22—25 September; at Verlaten L from the 26th— 28th. 

 On the 26th April 1921 I was only one day on Verlaten 1. and in the 

 morning of that day I searched for corals on Krakatau together with 

 Dr. BOSCHMA, as has been mentioned before. 



In October 1921 I paid a short visit of one day, the 23rd, to Krakatau 

 and of two days, 24th and 25th, to Verlaten I. The last trip 1 made to 

 Krakatau was in January 1922, for only two days, the 19th and 25th. 

 So altogether I was able to spend 16 days on Krakatau and 12 on Verlaten I. 

 If we now compare what JACOBSON found in 1908 and I myself in 

 1920—1921, we will have to reckon with the fact that I could collect on 

 the islands so much longer than JACOBSON. 



jACOBSON's trip to Krakatau lasted but three days, and he could spend 

 only a few hours on Verlaten Island and Lang 1. Lang I. has not been visited 

 by myself as I thought it better to confine myself to Krakatau and Verlaten I., 

 Lang I. being practically in the same condition as Verlaten I. as to situation, 

 altitude and vegetation. 



The total amount of animals found on Krakatau in 1920—1921 is 

 nearly three times that which has been found in 1908. JACOBSON recorded 

 from Krakatau 196 species (see Appendix A); from Verlaten I. only 29. 

 I found on Krakatau 573 species; on Verlaten I. 325. As already mentioned, 

 this increase of species may be accounted for not only by the lapse of 

 13 years between the two investigations, but having occasion to visit the 

 islands so often, I could collect many animals which were certainly already 

 on the islands in 1908 and escaped JACOBSON's notice because his time 

 was so limited. Besides, I used two methods of collecting, viz. trapping by 

 light and sifting, which apparently JACOBSON could not practise during his 



