DammermaN: Fauna of the Krakatan Islands. 91 



We see that the lake is least saline at the end of the rainy monsoon 

 (April-May) ; the highest salinity is observed at the end of the dry season 

 (Oct.-Nov.), on account of the strong evaporation during several months, 

 when there is little or no flowing in of fresh water. The salinity of the 

 small pool is, of course, greatly influenced by the rains. 



The rain-fall at Verlaten I. or Krakatau is not known and is hard to 

 deduce from the figures noted at different stations on the Java and Sumatra 

 coast along Sunda-Strait (see table on following pages) but certainly on 

 these islands there is still a marked difference between the rainy season 

 and the dry monsoon just as in Java. 



The following observation is also of interest:— In April 1920 at high-tide 

 there was a small but constant stream of water running into the lake out 

 of the northern part of the dunes which separate the lake and the ocean. 

 After analyzing it proved to be only 16.5 ^/oo saline; probably the water 

 was a mixture of fresh ground-water and sea-water as the ocean breakers 

 were running so high that they were even flowing over the top of the dunes. 

 The ground-water in the neighbourhood of the lake, even at a few feet 

 distance from the shore, was always perfectly fresh. 



The fauna of the lake is a very interesting one as no less than 51 species 

 of animals have been collected or observed (see List below). Many marine 

 forms were found which undoubtedly were enclosed after the connection 

 of the lake with the sea came to an end. 



List of species found in the lake, 



Pisces 13 



Teleostei 10 



hisecta 17 



Coleoptera 6 



Diptera 3 



Heteroptera 3 



Odonata 5 



Crustacea 5 



Arachnoidea 1 



Mollusca 4 



Vermes 4 



Bryozoa 1 



Echinodermata ..... 3 



Coelenterata 2 



Porifera 1 



Total ... 51 



The most remarkable fishes observed in the lake are a saw-fish (Pristis 

 spec.) of about 2,5 M. in length; some three sharks, noted by Mr. SlEBERS 

 April 1921; and a ray of 0.75 M. in length, with blackish-brown upper 



