SUNIER : Marine fish-ponds of Batavia. 187 
27th April 1918 in pond G (cf. Map II) of Mr. Görs’s pond-system near 
Muara Karang, which pond had been entirely cleared of fish a few months 
before, and had been left without bandeng for some time after thoroughly 
renewing the water, so as to give the submerged vegetation the opportunity of 
developing unhampered, I was able to observe a number of young 
Ruppia plants appear among an Enteromorpha-vegetation that had first 
developed in this pond. On the 14th of May following a good deal of 
Ruppia was already to be seen among the Enteromorpha. By June 15th 
the Enteromorpha had virtually disappeared altogether, an extensive Ruppia- 
vegetation having developed. On July 16th large areas in the northern 
half of pond G of Map II had been entirely occupied by Ruppia. On July 30th 
conditions were very much the same. After that I did not see the pond 
again till September 6th 1918, when the Ruppia-vegetation in the northern 
half of the pond was still present, but appeared to have suffered a good 
deal from the bandeng which had meanwhile been let loose in the pond 
and had begun to eat the Rzppia-leaves (for this cf. Chapter V). In con- 
nection with this | could observe on September 24th, October 15th, and 
October 28th, how each time less remained of the Ruppia-vegetation. 
On November 18th what I found in the pond in question was no more 
than a few floating bunches of Ruppia, probably pulled loose by the 
bandeng, the leaves being frequently eaten away (cf. Chapter V). 
Just as for Chaetomorpha, the numerous data brought together in my 
diary, and those tabulated in the observation table (Table IV), do not 
warrant the conclusion that there should exist a definite influence of the 
salinity (within the limits observed: less than 3!/, °/j,—84.6 °/))) on the pre. 
valence of Ruppia rostellata. 
In the observation table (Table IV) the presence of Ruppia is reported ') 
with salinities ranging between 6.0°/,, and 42.4°/,,. According to entries in my 
diary I found on March 5th 1918, a.o. in the ponds A and B (cf. Map II) 
of Mr. Görs’s pond system near Muara Karang, a good deal of Ruppia 
rostellata. The water in those ponds was then almost fresh, or at any 
rate had a salinity below 31/,°/5. On the other hand, on September 
6th 1918 in one of the fry-ponds C (cf. Map Il) | found Ruppia in water 
possessing a Salinity of 57.9 Jo. Eighteen days later, September 24th 1918, 
I found the same Ruppia in the same pond at a salinity of 56.9 ®/oo. 
Accordingly the Ruppia plants which at both observations made an 
impression of being normal, had lived 18 days in water possessing a 
salinity of about 57 0/6. 
1) The observation-table giving only the composition of a sample of the submerged 
vegetation collected at the place where the mosquito-nets (cf. Chapter VII) had been 
placed, the fact of Ruppia or another component of the submerged vegetation not being 
mentioned, certainly does not mean that that component did not occur in the pond 
observed, nor even at or near the place of observation. 
