June — July 1SS4.) 



PSl'CHE. 



183 



branch going caiulad, giving branches 

 to the maxillary muscles in the head. 

 TIic cephalad branch divides into two 

 branches four and one-half millimetres 

 from the ganglion, both continuing their 

 course cephalad. 



The fourth nerve (fig. 11. 5. d) is a 

 very small nerve which divides into two 

 branches entering the maxillary muscles. 



77/c mandibular nerve. — The man- 

 dibular nerve (fig. 11. 4 and fig. v) 

 arises from the dorso-latero-cephalad 

 borders of the sub-oesophageal ganglion, 

 and continues laterad to the mandibles. 

 Before entering the mandibles three 

 branches are given oft" (fig. v. 2, 3, 4). 



The first branch (fig. v. 3) gives ofl" 

 two nerves which go caudad, entering 

 the mandibular muscles. 



The second branch (fig. v. 3) goes 

 laterad a short distance, then forks. Tlie 

 caudad fork, dividing into two branches, 

 enters the mandibular muscles. The 

 cephalad branch is united to a long nerve 

 going cephalad. This nerve forks one 

 and one-half millimetres from the base 

 of the mandibles. This nerve extends 

 caudad of its attachment to nerve 3 

 (fig. V), and enters a muscle. Just 

 caudad of its attachment to nerve 3 it 

 gives ofl" a very fine and delicate nerve 

 which goes cephalad into the mandibles. 

 Nerve 4 (fig. v) goes laterad two milli- 

 metres, then forks, one branch going cau- 

 dad to supply the mandibular muscles in 

 the head, tlie other branch going cepha- 

 lad into the mandibles. The mandibular 

 nerve gives oft" a branch at the point of 

 entering the mandibles, two branches 

 one and une-fointh millimetres from the 



base of the mandibles, and then forks at 

 a point two and one-fourth millimetres 

 from the base into two branches, which 

 continue their course cephalad. The 

 more minute branches of the mandibular 

 nerve are shown in fig. v. 



Other nerves. — A small nerve (fig. 

 II. 6) arises immediately caudad of the 

 attachment of the labial nerve on the gan- 

 glion, and divides into several branches 

 going to the adjacent muscles. 



From the lateral borders of the sub- 

 oesophageal ganglion two nerves are 

 given ofl", one on each side, going cau- 

 dad parallel to the commissures (fig. n. 

 S). These nerves enter the perivisceral 

 cavity. 



At the caudad part of the ligula, 

 three millimetres from the sub-oesopha- 

 geal ganglion on the meson, are at- 

 tached two long nerves going caudad 

 (fig. II. 7). These nerves are joined 

 to the labial nerves by neurilemma 

 and b}' two very fine nerves, one on 

 each side. At the ganglion each nerve 

 gives olT two small, delicate nerves 

 which are joined to nerve 6 (fig. 11). 

 The main branch continues caudad, liut 

 no caudal attachment was found. The 

 cephalad attachment of these nerves is 

 not shown in fig. 11, having been dis- 

 sected away to show the cephalad ex- 

 tremity of the gustatory nerves. 



4. The commissures. — The cau- 

 dad end of the sub-oesophageal ganglion 

 terminates in two large white cords, the 

 commissiucs (fig. 11. 9, fig. vii. 4). 

 These commissures are similar to the 

 commissures of the body, and join the 

 sub-oesophageal ganglion to the first 



