WHAT AN INSECT IS LIKE: OUTSIDE 11 



the thorax. They are more or less "telescoped" from front 

 to rear, with infolded joining membranes and overlapping 

 edges. Each segment, moreover, is capable of a some- 

 what bellows-like expansion at its infolded lateral margins. 

 The tails (or cerci) are long, tapering, close-ringed, many- 

 jointed appendages that function as "feelers" to rearward. 



2dA IstA Cu 2 



5 th a 4ttiA. 



Fig. 5.— The venation of the wings of the stonefly, Perla capitata. Principal veins are marked by 

 capitals; cross-veins, by small letters. 



