260 ELEMENTARY ZOOLOGY. 



which have been considered to be for the purpose of hear- 

 ing. It is believed that the hearing is best developed 

 in those air-living forms in which definite noises are made, 

 as in the crickets, katydids, cicadas, and the like. 



The most remarkable organ of sense in the group is the 



V , 



FIG. 104. Antenna of male mosquito (Culex pipiens). By J. W. Folsom. 



Questions on the Figure. Compare with the antennae of the 

 female (See Fig. 103). What are the differences between the head 

 and its appendages in the male and female mosquito? What is 

 believed to be the function of the male antennae? Evidences for 

 this view? 



compound eye, which is found both in the Crustacea and 

 the insects. There are often, in addition, simple eyes 

 (ocelli). The general structure of the compound eye is 

 suggested by Fig. 105, but the student must be referred 

 to more advanced texts for the details of its structure 

 and use. 



