242 MANUAL OF NATURAL HISTORY. 



fore-legs fitted for seizing prey, posterior pair cili- 

 ated, and formed for swimming. Aquatic. 



1. Family. — Boat-Flies (Notonectidae). General 



form boat-shaped ; head broad ; eyes very 

 large, and so formed that the insect may see 

 both above and below when swimming ; 

 wings generally deflexed ; posterior legs 

 long and broadly ciliated, forming excellent 

 paddles. 



2. Family. — Water -Scorpions (Nepidae). Head 



small ; rostrum short ; body depressed ; ab- 

 domen sometimes terminated by two long 

 slender filaments; fore-legs especially adapted 

 • for seizing prey, the thighs being dilated, the 

 tibiae curved, united with the tarsus, and 

 fitting in a channel on the under part of the 

 thighs. 



II. SUB-ORDER.— Land-Bugs (Geocorisa). 



Antennae usually long, very seldom concealed, legs 

 fitted for walking. Terrestrial, or only found, in a 

 few cases, on the surface of the water. 



3. Family. — Sand-Bugs (Galgulidae). Eyes pedun- 



culated j body short and depressed ; antennae 

 small, placed in a cavity beneath the eyes ; 

 rostrum short. In some the wing cases are 

 soldered together at the suture. 

 1. Family. — Jumping -Bugs (Acanthiidae). Eyes 

 large ; rostrum long and slender ; body de- 

 pressed, oval ; legs long ; antennae long or 

 short. Of small size. 



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