1881. 253 



This larva now proceeded to make itself a ease of Alisma plantago, 

 first securing a piece of leaf that was near, and then fastening this 

 under another leaf that floated by ; three hours after it thus hid itself 

 I turned the leaf over, and found the piece by this time fashioned 

 into a suitable oval shape, and attached to the oval edge of the leaf, 

 so that on that side there was no need of cutting : next day the larva 

 was shaping the second piece — not merely by cutting a channel, but 

 by eating away a large irregular hole outside its case, still, however, 

 leaving a narrow isthmus uncut, so as to keep itself securely moored 

 for a day or two longer ; but at last when it had to stretch out further 

 and further to continue feeding on the leaf it made its case tight, cut 

 the mooring, and floated off. When the larva is about to pupate it 

 attaches its case at the edge of one side beneath some floating leaf or 

 submerged stem, often (as Mr. Jeffrey found a great number) to the 

 decumbent stems and tough fibrous roots of the Myosotis bared by 

 the action of water, but always fixed edgewise ; indeed, the only 

 exception was in a case fixed flat against a piece of Sparganium. 



After the larva had spun up, from seventeen to twenty days 

 elapsed before the appearance of the imago ; I bred seventeen speci- 

 mens in all at intervals from June 21st to August 26th. 



Fortunately for our knowledge of the interesting early part of 

 the economy of nymphcealis, Mr. Jeffrey detected amongst some 

 Potamogeton nutans, gathered promiscuously as food for his larva?, a 

 large leaf, having eggs deposited on the under-surface, hut without the 

 least covering ; and cutting off the extreme tip of the leaf on which 

 were six eggs, for himself, most kindly sent me, on 8th of August, the 

 rest of the leaf bearing about a hundred eggs of a pale ochreous- 

 greenish colour, close together in a flattish mass near the margin from 

 which the tip had been severed ; three days later, by aid of a lens, I 

 could see two black specks on each egg, and in two more days these 

 were distinct enough, and the day after that, August 14th, the larva? 

 all hatched, and soon liid themselves by mining into the under-side of the 

 leaf, not, however, before I had observed and noted their black heads 

 and collar plates with pale greenish-yellow translucent bodies. On 

 the same day Mr. Jeffrey was watching the six eggs he had retained, 

 having placed the severed bit of leaf on the upper surface of a fresh 

 gathered leaf put in water ; and at about 8 a.m., saw the little creatures 

 leave the egg-shells, and crawl over the upper surface of the fresh 

 leaf, and from thence to the under surface, which they at once entered 

 by mining on either side of the midrib near the base. In this manner 

 my young brood remained ensconced from thirty hours to three days, 



