THE ANIMALS AND MAN 



neck, however, and that at the bases of the legs and wings 

 is soft. Why is this necessary? Note that the soft skin of 

 the neck is well protected by the projecting saddle-shaped 

 horny piece on the front thoracic body-ring. Another use of 

 the firm cuticle, or exo-skeleton, as it is called, is to afford 

 solid points of attachment for the many muscles of the 

 body, the locust having no bones or any kind of internal 

 skeleton. (In a few places there are processes or continua- 



antennse 



auditory organ 

 'head compound eye! 



femur'' 

 libra''' 



larsal 



■ovipositor 



Fig. 2. Locust, with external parts named. 



tions of the exo-skeleton projecting internally and these are 

 sometimes called the endo-skeleton.) 



That part of the body behind the thorax is called the 

 abdomen. Examine the upper side of the first (nearest 

 the thorax) body-ring of the abdomen, and find two small, 

 nearly circular, thin places looking like little windows. 

 These are the hearing organs, or tympana, of the locust. 

 The sound-waves striking against these thin tightly stretched 

 bits of the body wall, set them into vibration, and these 

 vibrations stimulate a tiny vesicle and nerve-ganglion 



