— 43 — 



The antennal nerves. — These arise from the latero-cepha- * 

 lie angles of the supraoesophageal ganglia. 



The optic nerves. — These arise caudad of the origins of 

 the antennal nerves. Determine the number of divisions of 

 each optic nerve. 



The crura cerebri. — These are the two, large cords, one on 

 each side, connecting the supraoesophageal ganglia with the 

 subcesophageal ganglion, and forming with these ganglia 

 the nervous collar of the oesophagus. (The singular form 

 of crura is eras.) 



The vagus nerve. — Just cephalad of the supraoesophageal 

 ganglia there is a minute ganglion, the frontal ganglion ; 

 this is connected by an arching nerve on each side with the 

 crura cerebri ; from the frontal ganglion there extends ceph- 

 alad a small, branching nerve ; from the frontal ganglion 

 there also extends a nerve which passes caudad, between 

 the supraoesophageal ganglia and the oesophagus, and ven- 

 trad of the aorta (which is usually turned to one side in 

 opening the specimen as this one is opened), to a minute 

 ganglion on the middle line of the oesophagus, caudad of 

 the supraoesophageal ganglia. From this minute ganglion 

 two nerves extend, one on each side, to the sides of the ali- 

 mentary canal, which they follow to the proventriculus, 

 where they divide into many branches. This system of 

 nerves and ganglia are termed the vagus nerve. 



Tke stiboesophageal ganglion. — This is the large ganglion 

 on the meson, ventrad of oesophagus. From it two large 

 cords pass caudad to the first thoracic ganglia. 



From the subcesophageal ganglia nerves extend to the 

 labium, the maxillae, the mandibles, and to other parts of 

 the head. The beginning students who are taking a short 

 course in entomology need not trace out these nerves. 

 Other students may use as a work of reference a paper on 

 this subject by Dr. William C. Krauss, published in 

 "Psyche," vol. IV, pp. 179-184. 



