Microscopical Essays. 27,9 



plunge themfelves therein but rarely. 2. Others that live only 

 In the water, and cannot fubfift out of it. 3. Many, after 

 having lived in the water while in the larva and. pupa Hate, come 

 out afterwards with wings, and become entirely terreftrial. 

 4. Some undergo all their transformations in the water, and then 

 become amphibious.. 5. Others again are born and grow in. the 

 water, hut undergo their pupa ftate on. dry land, and after they 

 are arrived at their perfecl: ftate live equally in air and water. 

 & Laftly,, there are fome who live at the fame time part in the 

 water, and part on land, and which after their transformation 

 eeafe to be aquatic. 



Among the infe&s which remain on the fuperficies of the 

 water, are fome fpiders, which run with great addrefs and 

 agility, without moiftening their feet or their body 5 when they 

 repofe themfelves, they extend their feet as much as poffible. 

 There are alfo aquatic bugs, which fwim, or rather run, on the 

 water with great velocity, and by troops; another bug walks 

 very flowly on the water ; the gyrinus moves very fwiftly, and in <4« 

 circles. There is a fpecies of podura * which live in fociety, and fr~ 

 are often accumulated together in, little black lumps. Thofe ill- 

 lefts which always live in the water are generally born with the 

 figure which -they preferve during their whole lives, as the mono- ^ 

 culi, crabs, feveral kinds of water- mites, &c. 



The number of thofe which, after having lived in the water, 

 leave it when in a winged ftate, is very great : among thefe we 

 may reckon the lib^llula,_ the ephemera^ the phryganea, culices, f- 

 tjp.ulsBj and fome fpecies of mufcae.. All thefe, when in the larva 



and 



De Geer Difcours fur les Infecles, torn. 2, p. 103., 



