438 SUPPLEMENT 



doned the shell, which from this moment was completed. 

 The whole of these labours lasted for about three hours." 



M. Miger has seen three hydrophili thus spinning their 

 shells under his immediate inspection. But he was unable 

 to follow them but once in their first labour, because it is 

 difficult, at this time, to observe, without interrupting them ; 

 but this is not the case when the oviposition has commenced. 

 The insect may be drawn out of the water, and even a 

 portion of the shell removed, without the hydrophilus shew- 

 ing any apprehensions of the observer, or discontinuing its 

 operations. 



Three females which this naturalist had put into a vessel 

 filled with water, but without any foreign body which was 

 proper to serve as a fixed point for their shells, did not spin, 

 but laid, however, all the three, a sort of cartilaginous, 

 oblong, and yellowish shell, of the bulk of a grain of barley, 

 and which, being detached from the anus, fell to the bottom 

 of the vessel. Having opened them at the end of some days, 

 he found then neither eggs nor fluid. Not being certain 

 whether these individuals spin their shells, he does not 

 venture to decide, if these last are the production of an 

 abortion, or a mass of superabundant fluid. But as they did 

 not enclose any egg, and as they were much smaller than 

 the ordinary shells, this last opinion appears the most 

 probable. 



The spinnerets are scaly, conical threads, two lines in 

 length, and composed of two articulations, the first of which 

 is of a clear fawn-colour, spotted with brown, and the second 

 of this last colour, and much smaller. It is terminated by a 

 Avhite and transparent lash. Two other conical appendages, 

 but fleshy and inarticulated, are placed as well as the pre- 

 ceding between two sorts of corneous and semi-circular lips, 

 terminating the last ring of the abdomen. The fleshy por- 

 tion of this ring, by the facility of contraction and dilatation 



