CHAPTER VII. 
Order PLECOPTERA (Ple-cop'te-ra). 
The Stone-flies. 
The members of this order have four membranous wings , 
with comparatively few or with many cross-veins ; the hind 
wings are much larger than the fore wings , and are folded in 
plaits and lie upon the abdomen when at rest. The mouth- 
parts are of the biting type of structure , but are frequently 
poorly developed. The metamorphosis is incomplete. 
The name of this order is from two Greek words: plecos , 
plaited; and pteron, a wing. It refers to the way in which 
the hind wings are folded when at rest. 
Although the mouth-parts are of the biting type of struc¬ 
ture, the mandibles are often small, flat, and membranous, 
and evidently of little use. It is probable that as a rule 
the adults eat but little. The antenna: are long, tapering, 
and many-jointed; and in most species the caudal end 
of the abdomen is furnished with two many-jointed bristles. 
The nymphs are aquatic. 
This order includes only a single family- 
Family Perlid^: (Per'li-dae). 
The Stone-flies. 
Those boys fond of fishing know that a good place to 
find bait is under stones in streams. And doubtless they 
have often observed that in the swiftest portion of the stream 
the turned-over stones have clinging to the lower surface 
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