8 Expedition of 1906 



manner, would clearly have been of the greatest interest. A 

 thorough investigation of the group of islands planned by Treub 

 for the following years had unfortunately to be given up, and it was 

 not until ten years later, in March 1897, that the project "was carried 

 out, when Treub, Penzig 1 , Raciborski, Boerlage, and Clautriau took 

 part in a second exploration of Krakatau. 



During the interval of ten and a half years between the first and 

 second expeditions there had been a considerable increase in the 

 number of species in both coast and inland floras. In 1897 the total 

 number of species found on Krakatau and on the other islands visited 

 by the expedition, Verlaten and Lang islands, which in 1886 were 

 entirely destitute of vegetation, amounted to 62 species of vascular 

 plants, including 50 phanerogams and 12 vascular cryptogams, in 

 addition to the seeds and fruits of 26 phanerogamous plants washed 

 up on the beach. The assemblage of plants had become denser and 

 the ground was in places completely covered; the development of 

 characteristic plant-associations (formations) had begun. On all 

 three islands the Pes-caprae formation or association formed a 

 dominant feature on the beach. Mangrove plants were unrepre- 

 sented and the first sign of a strand-forest was noticed only 

 on Verlaten island. 



Further inland the vegetation constituted a kind of grass- 

 steppe characterised by grasses, occasionally reaching the height 

 of a man, which in several places formed a thick jungle. Lower 

 grasses grew on the hills and ridges in association with numerous ferns 

 and sparse phanerogams. As in 1886 ferns largely predominated on 

 the rock surfaces. Shrubs were poorly represented and trees were 

 very rare. 



Of the 53 phanerogams found in 1897, Penzig estimates that 

 32 species (60*39 %) na 6! reached the islands by ocean-currents, 

 17 species (32*07 %) by wind-agency, and only 4 (7'54 %) had been 

 transported b} r fruit-eating animals or by man. 



II. The expedition of April 2427, 1906, to the 

 Sunda Strait region and to Krakatau. 



In 1905 another visit was paid to Krakatau, in which Th. Valeton, 

 M. Golenkin and other botanists took part. The results of this 

 expedition have not been published. 



During my residence at Buitenzorg I made application, in company 



1 Penzig, O. " Die Fortschritte der Flora des Krakatau." Annates da Jardin 

 bvtanique de Baitenzorg, 1902. Vol. in. ser. 2, pp. 92113. 



