THIRD WEEK. 



NEKDED. A number of grasshoppers, including both sexes. 



FIRST HOUR. Study the union of the wing with the body. Make 

 a drawing both from above and below. Examine the wing in all posi- 

 tions, and describe the action of the hinge parts. 



SECOND HOUR. Draw the first two abdominal segments, making 

 out carefully the division between the thorax and abdomen. Draw on 

 a larger scale the ear. Notice the chitinous border of the tympanum, 

 and note the shape and position of the lateral and central processes of 

 the tympanum. Notice the spiracle near the front edge of the ear, and 

 note the position of all the spiracles on the insect's body. 



THIRD HOUR. Male. Draw carefully the end of the abdomen as 

 seen from the side, numbering all the parts so as to indicate the seg- 

 ments to which they appertain. Now, grasping the abdomen near the 

 thorax, slowly compress it until the organs are widely spread, and draw 

 again. Note the cerci, the three anal flaps and the clasping organ. 

 Female. Draw twice from the side, as directed above, noting the cerci, 

 the anal flaps, the four valves of the ovipositor, the egg guides and the 

 extensile glands between the eighth and ninth segments below. Try 

 to homologize the parts in the two sexes. 



