INSECTS 117 



the main portion of the leg ; (d) the tibia, next in size to the femur ; 

 and (e) the tarsus which is composed of five portions, the last, or 

 proximal, of which bears a pair of strong sharp claws, with a pad 

 of tissue, the pul villus, between them. 



The legs of the Grasshopper are adapted for maintaining a firm 

 position on the stems and leaves of plants. The comparatively 

 large size of the metathoracic femur makes possible the presence 

 of the large muscles which the animal uses in jumping. 



3. Abdomen 



The abdomen consists of eleven segments. The general external 

 structure of each segment is the same as previously noted in the 

 thoracic segments. At each end of most of the abdominal seg- 

 ments there is an articulation, or connection, with flexible tissue 

 so that a considerable degree of flexion between the segments is 

 possible. Not all of the abdominal segments are complete. Thus 

 the first abdominal segment, which is used with the metathoracic 

 segment, has only the tergum present, and the same is true for the 

 last abdominal segment. In segments ix and x there is an almost 

 complete fusion of the two sterna. (W. f. 54.) 



The anterior abdominal segments are larger than the posterior 

 ones, and there is a gradual tapering off in size so that the posterior 

 end of the abdomen, which carries the external genital organs, is 

 fairly pointed. On each of the first eight abdominal segments there 

 is a pair of respiratory openings, or spiracles, situated laterally. 

 Altogether there are ten pairs of spiracles, the other two pairs 

 being situated on the mesothoracic and metathoracic segments. 



In the female, the external genital apparatus, which is adapted 

 for laying eggs (ovipositor), consists of two curved plates, the 

 dorsal and ventral valves, project ng from the posterior end of 

 the body. These valves are so fashioned that they can be used 

 for drilling a hole in the soil into which the eggs are placed. In 

 the male Grasshopper, the external genital apparatus consists of 

 several highly specialized chitinous structures which function in 

 the transference of sperm to the seminal receptacle of the female. 



B. Organ Systems 



The general plan of the internal arrangement of the various 

 organ systems of the Grasshopper is essentially the same as pre- 

 viously described for the Crayfish. 



