200 THE DRAGON FLY. 



their transformations, and however much they may 

 vary in appearance, have the forms or cases of the 

 whole, the one within the other, in the same manner as 

 those that cast their skins without altering their forms, 

 are understood to have the rudiments of all the skins ; 

 but where the transition from one state to another is great, 

 a period of quiescence is required ; for which the insect 

 prepares, by forming for itself a case, out of materials 

 furnished from its own substance. With water insects, 

 the transitions are not so great ; and therefore there is less 

 quiescence, and a less change in the quantity and nature 

 of their food. The phryganece and ephemera, already 

 mentioned, have, both in their larva and their chrysalid 

 state, a very remarkable resemblance to the perfect fly, 

 only they are without wings, which would be worse than 

 superfluous, so long as they inhabit the water. When 

 they come up to the surface, it is only the bursting of a 

 thin membrane, in which they are enclosed, and they 

 are free and fit for their new mode of life. It is the 

 same with the dragon fly. The head of the larva bears 

 a very great likeness to that of the fly ; the body is also 

 like, only it is not so thick at the thorax, most likely, 

 because the muscles that are to move the future wings 

 are not developed till they be needed. The larvae of the 

 dragon flies are of a dusky colour, inclining to brown or 

 green, according to the species, those of the Lib. varia, 

 the largest and most showy of the British species, are 

 brown, and far from handsome. They have the same 

 hard mandibles as the winged insects, and six legs, 

 ending in feet armed with claws. They eat voraciously, 

 and cast their skins several times before they arrive at 

 their full growth. No prey comes wrong to them ; for 



