109 



recorded in P e n z i g's list. This shrub only grows on the heavier 

 soils either saline (and very frequently so) or not. Possibly it was 

 collected in a locality with a badly pervious soil consisting of fine 

 compressed ashes, such as was present in 1906 at the base of the rupt- 

 ure at Zwarte Hoek. It is very probable that part of the localities 

 investigated by Penzig possessed a badly pervious soil; this may 

 be deduced from the fact that many young specimens were found of 

 Ophiog/ossum reticulatum L. (sensu lato), recorded by Penzig 

 under the name of O. moluccanum Sch/echt.) This is a terrestrial 

 fern, occurring exclusively on badly pervious soils or on soils whose 

 surface is covered by a badly pervious layer of fine mud, in not 

 too dry localities, especially in the cultural zone, often in premises, 

 on road-sides, in tea-plantations, rather frequently also in teak-forests, 

 Penzig says nothing about the nature of the substratum on which 

 he found this plant, neither does he tell which were the ferns forming 

 associations (see p. 105) between the grasses in the higher localities 

 reached by him. Generally speaking the vegetation was rather 

 monotonous and the number of species found was comparatively 

 small. 



Raciborski collected in 1897 on Krakatao on rocks and on the 

 soil a number of Schizophyceae and Bacillariophyta. Of the first 

 of these groups he gathered 6 species not found by T r e u b; the 6 

 species discovered by Treub in 1886 seem not to have been 

 found back in 1897' 1 ). This should not be considered proof that the old 

 species had disappeared in 1897 and that the new ones were intro- 

 duced after 1886; it is much more probable that in 1886 already 

 numerous species of algae were present on the island and that both 

 Treub and Raciborski collected only a few of these. The 2 

 species of mosses which Treub had collected in 1886 (see p. 60) 

 were found back by Raciborski who collected furthermore 

 a species of Anthoceros (Hepaticae), a species of Hygrop/iorus 

 (Agaricaceae) and numerous specimens of the small Myxomyceta 

 Physarum cinereum Pers. Here also Penzig does not give any 

 further details. 



After having ascended the mountain for about an hour, a time 

 very much too short for allowing a somewhat intensive investigation, 

 it became clear to Penzig and his companions that they could not 

 possibly reach the top and they returned to their vessel. They cannot 



l ) Of course assuming that in both cases the determinations were correct, which 

 cannot be decided as long as the specimens are not found back. 



