46 



the seeds and fruits washed ashore contribute to lastingly enrich 

 the flora. 



Everyone who is, from personal view, acquainted with the drift- 

 zone will admit that on the beach examined by Treub a great 

 number of small seeds and fruits may have been present that remained 

 unobserved '). For persons who never saw tropical drift-zones a look 

 at the fine picture given by Ernst-) will suffice. 



On the shore of Krakatao Treub found young specimens of: 



1. Erythrina spec. 



Until now 2 species of Erythrina have been found on the beaches 

 of Krakatao. The first of these, E. variegata I., var. orientalis Men: 

 (H. indica Lamk.) is in Java a rather common tree of sandy beaches; 

 in the interior it is often cultivated. Its indehiscent pods are often 

 found washed ashore ' ! ); like the seeds they possess floating power. 

 The second species, E. fuscci Lour. (E. ovalifolia Roxb.) is an inhabitant 

 of riversides in the lowland plains. Its pods burst when ripe; the 

 seeds can float and are often carried by the rivers to tlie sea. They 

 frequently reach the shore but develop into trees only where the 

 sweet ground-water rises near the surface and consequently may be 

 easily reached by the roots of the seedlings. It is impossible to 

 decide which of these two species was found by Treub; neither 

 of them was eleven years afterwards found back by Penzig in the 

 same locality. But in 1906 and 1908 only the first was seen at Zwarte 

 Hoek, so that it may have been this species that Treub collected. 



2. Calophyllum inophyllum 1,. See p. 44, No. 6. 



This species was not found back by Penzig in 1897 in the same 

 locality. Like the former it illustrates what I have said (p. 44) about 

 the dangers to which young seedlings on the beach are exposed. 



3. Cerbera odollam Gaertn. 



This species, at the present time named C. manghas L. is a 

 small tree locally frequent on clayey soils along tidal creeks and 



') Schimper | Indo-Malayische Strandflora (1891), p. 172| already pointed out 

 that in tlie drift-zone small fruits may easily escape the eye. The record (I.e. 160) 

 given by him of seeds and fruits washed ashore contains the names of many plants 

 not mentioned by I r e u b, but the seeds or fruits of which most probably land from 

 time to time on Krakatao. 



-) Neue Flora Vulkaninsel KraUatau (1907), plate IV, fig. 6. This increasing beach 

 should be compared with the decreasing one pictured on plate V, fig. 8, left side. 



3 ) G u p p y found them on the Reeling-islands in the drift-zone. 



