I7 2 ELEMENTARY ZOOLOGY 



Note on the head the large compound eyes. Note the 

 tumid convex clypens which composes most of the anterior 

 aspect of the head. Are ocelli present ? Compare the 

 antenna with those of the locust and water-beetle. Com- 

 pare also the mouth-parts and note that they differ radi- 

 cally from those of the locust and beetle. They are not 

 fitted for biting, but for sucking up liquid food (the nectar 

 of flowers). Note the absence of a movable flap-like 

 labrum (a minute narrow stiff piece, bearing at each lateral 



compound eye, 



antennae. /... 



prothorax\ 



labial 

 palpi 



proboscis'' 



tarsal segments 



FIG. 41. Body of the monarch butterfly, Anosia plexippus, with scales re- 

 moved to show the external parts. 



end a small group of fine brown hairs, represents the 

 labrum), the entire absence of mandibles, and the absence 

 of a movable flap-like labium. The labiiim is a fixed 

 chitinized triangular piece forming part of the floor of the 

 head. Note the long slender proboscis coiled up like a 

 watch-spring. (In fresh specimens- this proboscis can be 

 uncoiled and will be found flexible. If dried or alcoholic 

 specimens are being studied, the head of the butterfly 



