1908] Nervous System of the Larva of Corydalis 115 



group. Thus the nerve on passing to the upper portions of the 

 body is protected and held away from the viscera. Branch 4, 

 like branch j, passes underneath the muscle-libers of m,, then 

 below the larger lateral tracheal tube and innervates the lateral 

 filament. Branch 5 consists of a small nerve which originates 

 from the proximal part of branch 4. It generally extends laterad, 

 passing under the lateral muscle fibers of m2 (Fig. i) and extends 

 to the lateral trachea, where it unites with the tracheal nerve 

 described in connection with branch i. 



In the seventh segment, branch i of the lateral nerve trunk 

 may be absent. When present, it does not join the transverse 

 nerve as is generally the case in the other segments, but ter- 

 minates in the ventral diaphragm. 



The ventral nerve trunk {v), originates from the ventral 

 side of the ganglion and extends caudo-ventrad innervating var- 

 ious of the more ventral muscles. Branch 4 passes betw^een the 

 muscles and the body-wall and innervates the tracheal gills (Fig. 



Because of its inconspicuous position this nerve has been very 

 generally overlooked though it is probably to be found in other 

 groups. 



The First Abdominal Ganglion. Unlike the rest of the 

 abdominal ganglia the first is situated below the ventral muscles. 

 It may be located readily by the presence of the diagonal and 

 transveres muscles, which pass dorsad of it (Fig. i). The nerves 

 of this ganglion are homologous to those of the following ganglia, 

 although they show greater tendency to variation than the latter. 

 Thus branches i and 2 may sometimes arise as a single nerve 

 independent of the main lateral nerve. Moreover, branch i 

 ramifies more freely than do its homologues of the following seg- 

 ments and it has not been observed to be connected with the 

 transverse nerve, but seems to innervate certain ventral muscles. 



The Eighth or Terminal Ganglion (Figs. 10, G. 8.) The 

 terminal ganglion of the central nervous system has been pushed 

 cephalad into the central portion or even to the anterior border 

 of the seventh segment, taking the normal position of the seventh 

 ganglion, which, also, has been forced cephalad, and is situated 

 at the caudal border of the sixth segment. The seventh and 

 eighth ganglia are united by two very short connectives, which 

 are generally not longer than the diameter of the last ganglion. 



