280 



MANUAL OF ELEMENTARY ZOOLOGY 



The sexes are separate. 



alimentary canal is supplied by a visceral nervous system 

 which receives nerves from the circumcesophageal com- 

 missures and the brain. Its principal ganglion lies on 

 the upper side of the crop. The sense organs include 

 the large compound eyes, which resemble those of the 

 crayfish in structure, the antennas, which are tactile and 

 olfactory, the maxillae, which are said to possess the 

 sense of taste, the tactile anal cerci, various sensory 

 bristles, and possibly a pair of oval, white patches on 

 the head, above the bases of the antenna?, known as the 

 fenestra. 



The testes are small, paired 



organs, 

 Organs of u j 



Reproduction, e m u e u 



ded in the 

 fatty body below the 

 fifth and sixth ab- 

 dominal terga. In the 

 adult they are no 

 longer functional. 

 Two vasa deferentia 

 lead backwards and 

 downwards from them 

 to the seminal vesi- 

 cles, which are beset 

 with short finger-like 

 processes and lie side 

 by side to form the so-called mushroom-shaped gland. 

 The seminal vesicles join behind to form a muscular 

 tube, the ductus ejacalatorius, which opens by a medium 

 pore between the ninth and tenth abdominal sterna. 

 A gland of doubtful function, known as the conglobate 

 gland, lies below the ductus ejaculatorius and opens with 

 it. The ovaries are paired organs in the hinder part of 

 the abdomen, each consisting of eight tubes, which show 

 swellings corresponding to a row of ova. There is a 

 single, short, wide oviduct which opens on the eighth 

 abdominal sternum. On the ninth sternum a pair of 

 branched colldcrial glands pour out by two openings a 

 secretion which forms the egg-cases. There is an unequal 

 pair of spermatheca?, which open between the eighth and 



Fig. 184. — A diagram of a transverse 

 section of an insect. — After Packard. 



/., Femur of leg ; g., gut ; h., heart ; «., nerve- 

 cord ; st., stigma ; tr., trachea; w. wing. 



