68 ANIMAL BIOLOGY 



the grasshopper's range of vision compare with that of the 

 crawfish ? 



Are the antennae flexible ? What is their shape ? Posi- 

 tion ? Are they segmented ? Touch an antenna, a wing, 

 a leg, and the abdomen in succession. Which seems to be 

 the most sensitive to touch ? The antennae 

 are for feeling ; in some species of insects they 

 are also the organs of hearing. 



The mouth parts of a grasshopper are highly 

 specialized. They should be compared with 

 the mouth parts of a beetle shown in Fig. 113, 

 since the mouth parts of these two insects 

 correspond closely. If the grasshopper is fed with a blade 

 of fresh grass, the function of each mouth part may be 

 plainly seen. It is almost impossible to understand these 

 functions by studying a dead specimen, but a fresh speci- 

 men is much better than a dry one. 



The upper lip, or labrum, is seen in front. Is it tapering 

 or expanded ? In what direction is it movable ? The dark 

 pointed biting jaws (mandibles} are next. Are they curved 



FIG. 114. a, FOOD TUBE OF BEETLE. 



b, gizzard; d, intestine; c, biliary vessels. See Fig. 127. 



or straight ? Sharp or blunt pointed ? Notched or smooth ? 

 Do they work up and down, or sideways ? The holding jaws 

 (maxilla), each with two jaw fingers (maxillary palpi ) are 

 behind the chewing jaws. Why ? The lower lip (labium) 

 has a pair of lip fingers (labial palpi} upon it. The brown 



