NERVOUS SYSTEM OF THE LOCUST. 



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riibrum^ and (7. Mvittatus, the nervous system does not vary at all, at 

 least so as to afford any specific characters. The following general 



account of the nervous cord is 

 based on that of the Rocky 

 Mountain locust, while, in work- 

 ing out the minor points, such as 

 the nerves of the end of the 

 abdomen and the sympathetic 

 (vagus) nerves and ganglia, 

 specimens of C. femur-rubrum 

 were used. 



The nervous system of the 

 locust, as of other insects, con- 

 sists of a series of nerve-centers, 

 or so-called brains (ganglia), 

 which are connected by two 

 cords (commissures), the two 

 cords in certain parts of the 

 body in some insects united into 

 one. There are in the locust 10 

 ganglia, 2 in the head, 3 in the 

 thorax, and 5 in the abdomen. 

 The first ganglion is rather larger 

 than the others, and is called the 

 brain. It is comjpressed from be- 

 fore and behind, being quite 

 deep, while the other ganglia 

 are more or less lens-sbaped and 

 flattened vertically. The brain 

 rests upon the oesophagus, 

 whence its name, supra-cesoph- 

 ageal ganglion. From the brain 

 arise the large, short, optic 

 nerves (Fig. 14, not lettered, but 

 represented by the circle behind 

 the brain, sp ; Fig. 15, op), which 

 go to the compound eyes, and 

 from the front arise the three 

 slender filaments which are sent 

 to the three ocelli (Fig. 14 

 From immediately in front, 

 down, arise the antennal nerves 

 (Fig. 14, at). 



The infra-cesophageal (i/), as its name implies, lies under the oesopha- 

 gus at the base of the head, under a bridge of cbitine, and directly 

 behind the tongue. It is connected with the supra-oesophageal ganglion 

 by two commissures passing up each side of the oesophagus. From the 



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