AND FUNCTION' 



255 



might be spoken of as the under side of the insect, 

 that part of the body which lies nearest the ground. The 

 adverb is ventrad, and is used as in the preceding. 



The other direction would necessarily have reference 

 to the back of the insect, and dorsal direction is the term 

 used here, and dorsad is the adverb. 



Now, in order that you may understand the applica- 

 tion of these terms, refer to Figure 202, and notice that 

 the two wings extend laterad from the body, and that the 

 antenna is cephalad of the base of the wing, and like- 

 wise that the wing is caudad from the antenna. The 

 utility and application of these terms will be more read- 

 ily understood with the specimen in hand and the ana- 

 tomical study in progress. 



EXTERNAL DIVISIONS OF THE BODY. 



An examination of the whole body will readily show 

 three divisions: the head, the thorax, and the abdomen. 



The Head, apparently one piece, contains the mouth, 

 eyes, and the long thread-like appendages known as the 

 antennae. 



The Thorax is in the central part of the body, furnish- 

 ing attachment for the wings and legs. 



The Abdomen is a slender portion extending caudad 



from the thorax. 



TITE HEAD. 



Fixed Parts of the Head. 



Compound Eyes. (Fig. 193, J5) Prominently situated 

 upon the lateral portions of the dorsal half of the head are 

 the two prominent compound eyes. The hand-lens will 

 reveal the honeycomb or network structure upon the 

 surface of these eyes. If a compound microscope is at 



