[DUPORTF.1 LARVA OF SPHIDA OBLIQUA WALKER 235 



muscle. Branch d is given off shortly after the nerve enters the back. 

 It runs back and forks at a short distance from the origin, its proximal 

 branch goes to the dorsal recti muscles and its second branch inner- 

 vates the dorsal diagonal muscles. In the dorsum of the prothoracic 

 segment nerve A splits up into four branches e, f, g and h. These 

 divide into numerous nerves which supply the muscles and integument 

 of the back. Branches e and f innervate the anterior portions of the 

 dorsum of the prothorax, branch h innervates the median portion and 

 branch / the posterior portion. 



Nerve B. The posterior nerve of the pro-thoracic ganglion arises 

 from the hinder side of the lateral border of the ganglion and runs 

 over the opening of the leg, giving off branches a and b which go to 

 the leg. It then bends slightly forward and near the bend gives off 

 branches c and d which run inward to muscles of the leg. Nerve B 

 then crosses on the ventral side of nerve A into the anterior portion 

 of the segment. Branch e extends forward to the neck. Distad of 

 the origin of branch e the nerve divides into four branches/, g, h and 

 k. Branch f runs forward for a short distance and then forks; 1 runs 

 inward innervating the transverse muscles, and 2 travels obliquely 

 forward innervating the muscles in the anterior portion of the segment. 

 Branch g runs back and enters nerve a; h goes to a branch of the 

 trachea and k travels to the ventral wall, where it divides into a num- 

 ber of sensory nerves. 



Nerves of the Second and Third Thoracic Ganglia (figs. 

 1 and 2, NG2, NG3). There is but one nerve from each of these ganglia, 

 given off from the middle of the lateral border. These are rather 

 large nerve cords, their size being about equal to that of the con- 

 nectives. 



The nerve runs in a lateral direction immediately in front of the 

 opening into the leg (ol.). The backward projecting nerve of the leg, 

 (a), is given off about 1 mm. or less distant from the ganglion. The 

 branching of the nerve of the leg is quite variable; occasionly the three 

 branches 1, 2 and 3, are given off as separate branches of the nerve 

 trunk NG; in other cases 1 and 2 originate as a common branch and 

 3 arises separately; usually, however, it was found that the nerve arose 

 as a single branch from NG and then divided into three branches. 

 Branch 1 runs towards the base of the leg and gives off branches x and 

 y; x runs backward and innervates a large muscle lying obliquely 

 across the inner and hinder edge of the opening into the leg ; y supplies 

 the muscles which lie at the inner side of the base of the leg. After 

 giving off branch y, 1 continues into the leg innervating the muscles 

 within this organ. Branch 2 travels towards the anterior side of the 

 base of the leg where it divides into several small nerves which in- 



