66 A GRASSHOPPER. 



c) A long, sub-cylindrical, segmented abdomen completes the body 



divisions. Determine the number of rings or somites that 

 compose it. Trace out the line that separates it from the meta- 

 thorax. In counting the somites you are likely to be puzzled as 

 you approach the tip of the abdomen, the ventral pieces of one or 

 two of the rings being absent. Other parts are also there, which 

 will be considered later. 



d) Let us examine carefully the more prominent appendages. On 



the front and near the top of the head are the jointed antennae, 

 certainly organs of touch and probably of smell also in some 

 insects. Compare with the antennas of a green meadow grass- 

 hopper, or a cricket. The legs have already been noted. Why 

 is the hind pair larger and longer than either of the other two 

 pairs? What prevents the animal from slipping when walking 

 or leaping ? 



e) Contrast the two pairs of wings in shape and structure. Pull the 



outer pair forward so as to expose the other pair folded like a fan 

 beneath the first. The outer wings, sometimes called tegmina 

 or wing covers, are not of much use in flight. What purpose do 

 they serve, then, in the economy of the animal ? To what divisions 

 of the thorax are the wings attached ? 



f) At the sides of the head are the two prominent compound eyes. 



Under the lens the cornea of each will be seen to be made up of a 

 great many hexagonal facets, corresponding to separate eye 

 elements in the structure beneath. Search the front of the head 

 for three small simple eyes or occelli. 



Exercise i. Fasten the grasshopper to a piece of sheet cork or soft wood 

 by two pins, spread out and pin down the wings of the left side and 

 draw a dorsal view on a scale of three. Label all the parts observed 

 and number the segments of the abdomen. 



Technical Note. Release the specimen from the pins and clip off the 

 left wings close to the body. Also remove the legs from the left side, 

 using the forceps in the process so as to secure the basal joint intact. 

 Sever the head from the prothorax and disconnect the abdomen at the 



