262 



NATURAL HISTORY. 



lice. In the first three of these families, the insect in ks 

 larva and pupa states inhabits the water, respiring like a 

 fish, having peculiar organs for this purpose at the sides 

 of the abdomen or at its end, while in the form of its 

 body it is quite like the insect in its perfect state. 



450. Of the Dragon-flies, the most conspicuous and 

 best-known family, there are about two hundred ascer- 

 tained species. These are the Swallows of the Insect 



