FIRST LESSONS IN ZOOLOGY 



long, slender hind body or abdomen, made up of several 

 segments or body-rings ; in flight this hind body acts as 

 a rudder to help steer the dragon-fly in its quick turnings 

 and swift dashes. Note the two pairs of long wings, 

 transparent and delicate, but firmly supported by a com- 

 plex skeleton of longitudinal and cross veins ; no other 

 insect surpasses this one in flight. Note the three pairs 

 of slender ^\ eak legs ; it uses its legs only occasionally 

 for perching, but it uses the U\o front pairs to form a little 



sort of trap or basket 

 which aids the great 

 mouth in catching and 

 holding small insects when 

 the dragon-fl)' is "hawk- 

 ing." Note the great head, 

 so loosely attached to the 

 body behind it that it can 

 be turned in any direction, 

 and can e\'en be so twisted 

 on the neck that the top 

 of the head 'will be direct- 

 ed downward with the 

 mouth facing directly up- 

 -ily. (Fnm. life.) ^^,j^,-j -phis head is com- 

 posed chiefly of two great shining compound eyes each 

 made up of man\' thousand eye-elements. When exam- 

 ined under a good hand lens the shining outer surface of 

 these eyes is seen to be composed of thousands of tiny 

 facets, each facet being the window or transparent outer 

 wall of one of these eye-elements. Each facet and the 

 eye-element behind it see one small part of the object 

 looked at, so that the image produced in the sensiti\-e part 

 of the back' of the e)'e is composed of thousands of 

 separate small parts, which make a sort of mosaic of 

 the object looked at. This seeing by compound eyes, 



