43G SUPPLEMENT 



them. We shall translate his account of these phenomena, 

 as the subject is one of very great curiosity and interest. 



" I beheld her attach herself to the reverse side of a leaf, 

 which was floating on the water, place herself across it, and 

 elongating her first pairs of feet, rest them on the upper part 

 of this leaf, and on each side, so as to make it assume a slight 

 curve. The abdomen was strongly applied to the reverse 

 of this leaf, and there were left visible at its extremity, two 

 appendages, which advanced and retired with quickness, and 

 from which there appeared to issue forth a white and gummy 

 fluid. This fluid was the principle of the shell, and the 

 appendages were the instruments of spinning in the hydro- 

 philus. Considering these instruments more attentively, I 

 saw that they deposited here and there, under the leaf, 

 around the abdomen, and without passing it, some silvery 

 threads, which applied successively on each other, formed a 

 small semi-circular pouch, in which the extremity of the 

 abdomen was, as it were, engaged. At the end of about ten 

 minutes, the hydrophilus, withdrawing its feet from the upper 

 part of the leaf, turned itself round quickly, and placed its 

 head below, without, on that account, taking away from the 

 shell the extremity of the abdomen. 



In this new position the insect kept itself nearly motion- 

 less, the four anterior feet being extended, and the two 

 others strongly attached underneath the leaf, and on each 

 side of the shell. During nearly an hour and a half, I 

 distinguished easily through the tissue, all the movements of 

 the spinning instrument. It was a pencil or brush, with two 

 slips, or thin tufts, which proceeded from right to left, and 

 from top to bottom, with much agility, in the interior of the 

 shell, and which invested the parietes and the external edges 

 of it with this gummy fluid of which we have been speaking. 

 This shell worked in this manner, and always inside, grew, 

 thickened, and finally became so compact, that it was po 



