Branch Arthropoda 69 



IV. — Notice that the head, convex in front and conccve 

 behind, is given its pecuhar shape by the very large 

 compound eyes. 



V. — Using the lens, iind the short antennae. How many 



segments has each .■' 



VI. — Near the base of the antennae find two small simple 

 eyes, the ocelli. 



VII. — Find a third ocellus between and above these two 

 ocelli. 



VIII. — Notice a slight projection covered with hairs, 

 sheltering the ocelli. 



IX. — In examining the mouth parts, first observe the large 

 size of both upper and lower lips. 



X; — Push these parts aside so that the mandibles — the 

 large toothed jaws — may be seen. Find beneath the 

 mandibles another pair of jaws, the maxillae; these 

 consist of several parts, as in the grasshopper, and 

 should be carefully removed and studied under the 

 microscope. 



XI. — Examine the thorax carefully, to find its three 

 segments, — the prothorax, the mesothorax, and the 

 metathorax. The lines of division may most easily 

 be seen on the ventral surface. Remember that each 

 of these divisions bears one pair of legs. 



XII. — Note the relative size of the thoracic segments. 

 The enlargement of which one gives the insect its 

 peculiar hunchbacked appearance .'' 



XIII. — Demonstrate the truth of the statement that the 

 anterior and posterior pairs of wings are attached to 

 the mesothorax and metathorax respectively. Reflect 

 upon the attachment of the wings in the other insects 

 studied, and remember that the place of attachment is 

 constant. 



