6 GENERAL ZOOLOGY 



ear, or tympanum (Fig. 2). The end of the abdomen in the 

 female is more tapering than in the male, and is furnished 

 with two pairs of blunt spines, which form an egg-laying 

 instrument, or ovipositor (Fig. 3). 



The Digestive System. After this brief review of the main 

 features of the external anatomy, or structure, of the grass- 

 hopper, we turn our attention to the organs of the interior. 

 And first, owing to its size and the ease with which its parts 

 may be examined, we may consider the digestive system. 

 The function of the digestive system of an animal is to pre- 

 pare the food for use by the different organs of the body. 

 In the grasshopper the organs of digestion are the food tube, 

 or alimentary canal, and its accessory organs, the salivary 

 glands (Fig. 3) and gastric caeca (gastric, pertaining to the 

 stomach ; caeca, plural of caecum, a pouch or cavity open 

 only at one end). 



The alimentary canal is a long tube extending through the 

 body and variously modified in the course of its extent. The 

 first division is the mouth, guarded on each side by the later- 

 ally moving mandibles. Between the mandibles, and arising 

 from the inner surface of the labium, is a short, brown, 

 tongue-like organ, the hypopharynx (Figs. 1, 3). At the 

 base of the hypopharynx opens the tube from the several 

 pairs of salivary glands. A portion of the slightly convex 

 surface of the inner side of the labrum is the epipharynx, 

 the seat of the sense of taste. 



Beyond the mouth the alimentary canal continues as a 

 short, curved esophagus (Fig. 3), which leads to a large crop, 

 armed with rows of spine-like teeth. Posterior to the crop 

 is a very small gizzard, also furnished with spines, opening 

 directly into a large, thin- walled stomach (Fig. 3). At the 

 anterior end of the stomach are attached the six tubular 

 gastric caeca, closed at one end but opening into the stomach 

 at the other. Beyond the stomach the alimentary canal 



