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in high cylinder jars. When the material has sunk to the bottom 
the larva will be found creeping slowly over the decaying material. 
More than once when examining the plants I saw the animals fixed 
in their normal position trying to detach themselves when the 
RR] 
Fig. 4. Larva in its natural position. Photo. — Fig. 5. Dorsal view of larva. Photo. 
plant was brought onboard. I have never found more than two or 
three on one plant. Altogether I have probably caught about 100 larvæ. 
It was my intention to keep the larvæ during the winter here 
in the laboratory, but in February they all died, probably because 
I had kept them at a too high temperature. As soon as the ice 
on the pond was melted, I went again to Donse to procure fresh 
material. Another great astonishment, but not so agreeable as when 
I found the larva. An enterprising man had bought the water in 
the ponds with intention of establishing an electricity work at the 
