208 TREUBIA VOL. II, 2—4. 
mention at all that he saw the kepala timah consuming other animals than 
mosquito larvae. The only two animals of which he states that he saw 
them devoured by Haplochilus panchax (HAM. BUCH.) in natural surroun- 
dings happen to be two mosquito larvae. 
SWELLENGREBEL (£2) says that he “repeatedly observed a Haplochilus 
almost to touch with its nose a larva without doing it any harm”. 
_ In this connection it may be useful to quote the two following passages 
from HILDEBRAND (3) who worked with Gambusia affinis (BAIRD and 
GIRARD), a Cyprinodontid whose usefulness in destroying mosquito larvae 
in aquaria and fountains was already well known. | 
HILDEBRAND (°°) then writes: “Placed another larva” (scil. an Anopheles 
larva) “in open water among fish” (scil. Gambusia affinis (BAIRD and 
GIRARD)). “This one too lay perfectly still, drifting like a small stick, 
“while fish swam all about, nosing it a time or two, but apparently not 
“detecting that it was alive and something to eat. Finaily it drifted near a 
“tuft of grass and with a surprisingly quick movement it swam into the 
“vegetation. . PURE AS WEAVER NIIT Ri 
“These feeding experiments, which were repeated many times, demon- 
“strated that the protective instinct in mosquito larvae is highly developed. 
“It was shown many times that the only protection an Anopheles larva has 
“from fish in Open water is inactivity. When the larva thus drifts along fish 
“evidently mistake it for an inanimate object, for, as already shown, they 
“may swim all around it for several minutes, even touch the larva with 
“the snout and yet not discover that it is food”. 
Further it is perhaps worth mentioning that in the examination of the 
stomach contents of many hundreds of sea-fish feeding on plankton it 
became apparent to me that these fish at least by no means eat continually, 
but that beginning to feed at a given moment they continue doing so 
until their stomach is closely packed, and then take a while to digest, 
during which time no fresh food is taken. Something similar was exhibited 
by the kepala timah described in Chapter VI which had stuffed themselves 
cramful of Nereidae. 
It moreover does not seem impossible to me that the kepala timah 
in natural surroundings, if perceiving the presence of the observer, would 
often be shy to take any food that has just been put into the water by 
that observer. 
There now remains only the observation by SWELLENGREBEL (®) 
concerning the contents of the alimentary tract of the 26 kepala timah 
examined by him. In Chapter VI we have already seen that in the Batavia 
empangs the kepala timah feed not only on mosquito larvae and pupae 
but also on all sorts of other small and sometimes a little bigger (Nereidae) 
live animals occurring in those empangs, and even also on live terrestrial 
animals such as ants which have accidentally dropped into the water. This 
of course is no matter of wonder, since it would be a far more surprising 
