88 HYDROCAMPA NYMPHS ATA. 



broad leaf of the floating Potamogeton ; but while 

 thus hidden themselves from view, their situation 

 could be made out easily enough by the large dis- 

 coloured curved blotches they caused on the leaf by 

 eating away the lower cuticle, and occasionally 

 making a small hole quite through the upper surface; 

 this leaf was nearly consumed by the fifth day, by 

 which time their shyness had in a measure worn off, 

 and they were then eating at the edges of another 

 leaf, their cases in view alongside, or lying above the 

 leaf; on the seventh day I noticed that the largest 

 larva had drawn the edge of a leaf a little way within 

 the opening of its case, and was then eating without 

 at all exposing itself; its companion at this time was 

 lying hidden in its case at the bottom of the water 

 for several hours, but it came up again and fed at 

 intervals, often protruding its front segments as it 

 crawled along the stems and leaves of the plant ; the 

 largest larva also at times protruded as many as 

 seven segments downwards, as though exploring the 

 depth of the water, but was generally the most intent 

 on its food ; sometimes, while reposing within its 

 case, it would lie on the upper surface of a leaf, in 

 which position it was not readily detected, the 

 assimilation being so perfect ; at other times, like 

 its companion, it would be floating concealed, its 

 case being just in contact with the edge of a leaf or 

 stem ; indeed, I found I could not isolate either of 

 them at such times in the clear space of water 

 between the leaves, for whenever I placed one there, 

 as lightly as possible, it seemed drawn, though 

 gently, yet with an attraction irresistible, towards 

 some part of the plant ; and if one end of the case 

 first touched it, the other end swung round till the 

 side of the case was in contact, when it would be 

 still. 



Finding the water much sullied by the frass, I 

 thought it necessary to have it changed every second 

 day, and each time this operation occurred the larvse 



