WATER DEVILS. 293 



affords two varieties ; both of a spare and slender make, but 

 one so delicately formed that even its body is scarcely thicker 

 than a line. This line is broken, however, by two prominent 

 hemispheric eyes, which though set really in the pigmy's mons- 

 trously long head, appear to be in the middle of his slender 

 body. He is usually wingless, or with only short parallel 

 elytra. This is the Hyd/rometa stagnorum, or Water Measurer, 

 a common frequenter, from March to August, of every ditch as 

 well as pond, where he glides about to murder the innocent. 



The fellow-destroyer * by which this is usually accompanied, 

 is a " bird of the same dark feather," only considerably more 

 bulky, and furnished with close-setting wings. He rows him- 

 self merrily along by his hinder feet, the sides of his body 

 being rendered impervious to water by a coat of silvery hairs. 

 Somewhat resembling him in habits and in form, though with a 

 body far less lean and long, and with its darker hues enlivened 

 by red and white, is another gliding or rowing destructive, 

 completing the "fatal three," which, insects themselves, are 

 for ever cutting short the slender threads of insect life. It was 

 not this morning visible on the willow pond ; and though we 

 have at times observed it on still waters, it usually prefers to 

 buffet the running stream, to glide, not with, but against the 

 current. This is known to naturalists as the Velia rivulorum. 



A word, now, for that little whirling devil, which, albeit 

 black in hue, is of less satanic seeming than the above ; for in 



* Gerris lacustris. 



