85 
) 
a thick skin so that hardly any trace of the eye is to be seen on 
the outside. It is a species of the genus Gobioides. 
Where the bottom is hard, stony, it is generally covered with 
huge sponges, which fill the dredge and thus make work on this 
kind of bottom rather difficult. The dredge very soon filis com- 
pletely with the sponges and thus, although even dragged for a 
longer time over the bottom, does not work any more; accord- 
ingly it gives a relatively poor result of the dredging and conveys 
a — probably — false impression of the bottom fauna being rela¬ 
tively poor. Eminently characteristic of the sandy (or sandy-muddy) 
bottom is an elegant Hydroid of the family Aglaopheniidæ {Lyto- 
carpus) its siender, often Meter-long stem, with the alternating 
feathershaped sidebranches carrying the polyps, being fixed in the 
bottom by means of a large tuft of fine rootiets. Often Comatulids 
and Ophiurids are attached to these Hydroids and sometimes they 
were found full of Caprella’s, while Bryozoans are attached to the 
basal tuft, and numbers of worms live among the rootiets. Upon 
the whole, these Hydroids are an ecological factor of importance. 
In the Sunda Strait the trawl several times came up completely 
filled with pumice stones from the Krakatau eruption in 1883. 
It was very interesting to notice that hardly any animal forms 
were found attached to these pebbles — probably because they 
are so light as to be rolling about by the slighest movement of the 
water from the current or the waves. Otherwise the bottom was 
muddy in nearly all the places where dredgings were made. I was 
very struck with the different character of the fauna in various 
places, in spite of the uniform character of the bottom. In some 
places the bottom must be almost covered by the elegant Retepora- 
like Bryozoan, Retiflustra Schønaui Levinsen, together with which 
were found numbers of another characteristic Bryozoan, a Stirparia 
i 1) Prof. SI u i ter found in a pumice stone from off Krakatau in 9 fathoms 
[ a specimen of a Bonellia, which he described as Bonellia pumicea (C. 
Ph. Sluiter. Die Evertebraten a. d. Sammlung d. Kgl. naturw. Vereins 
Nederl. Indien. Batavia. III. Die Gephyreen, Natuurk. Tijdschr. Nederl. 
Indié. L. 1891, p. 111); I have not observed any specimens of this interest¬ 
ing animal in the numerous pumice stones, which were brought up in 
various stations here. 
