ON THE PALPICORNES. 435 



thus remains dry. The external air then penetrates easily 

 between the elytra and the abdomen, so that the air easily 

 enters there. It is carried to the stigmata placed underneath 

 the elytra, along the two sides of the abdomen. When the 

 insect is desirous of returning to the bottom of the water-, it 

 quickly approaches the abdomen to the elytra, and stops at 

 the same time the vacancy which is between them, so that 

 the water can never penetrate it. 



Lyonnet has informed us of a very singular fact, the truth 

 of which is no longer to be doubted, after the excellent ob- 

 servations of the naturalist, whom w^e have quoted a little 

 above. It is, that these insects can spin, and make a sort of 

 nest or shell of silk, of an ovoid figure, in which they lay 

 and enclose their eggs. Degeer has found similar nests float- 

 ing on the water, and filled w^ith eggs, from which there 

 issue forth small larvae, which cannot be mistaken for any 

 other than those of hydro phi! us or dytiscus. 



He was never able to catch the moment in which they were 

 engaged in the construction of shells of this kind, but Lyon- 

 net w^as more fortunate, and informs us that he has beheld 

 the insect working at these shells, that it makes them with 

 the hinder part of the body, and that it adds a sort of brown 

 horn, a little curved, and solid. The use of this horn ap- 

 pears to him to be to retain the shell, when a gust of wind, 

 or any other accident might overturn it. 



These facts, as well as some others, are well developed in 

 the memoir of M. Miger. He speaks at first of the mode 

 of sexual intercourse in the hydrophili, which takes place in 

 the usual manner of other insects ; but the male crooks him- 

 self to the external edge of the elytra of the female, and 

 supports himself by means of the last articulation of the 

 anterior tarsi, which is formed like a triangular palette, or a 

 trow^el. This observer was witness of the manner in which 

 the female lays its eggs, and the singular shell which encloses 



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