[duporte] LARVA OF SPHIDA OBLIQUA WALKER 2.^7 



tween the origin and the point where it meets the transverse nerve, 

 branch d gives off a minute nerve which supplies the lateral setae. 



In the dorsum the nerve branches profusely, forming a rather 

 complicated net-work of nerves which innervates the muscles and 

 integument of the dorsum. 



The nerves of each pair of connectives and nerve A of each 

 abdominal ganglion is connected in the dorsum with a longitudinal 

 nerve (figs. 1 and 2, l.n.). This is a rather stout nerve which runs the 

 entire length of the segment, being attached to both conjunctivas. 

 The ends of the several longitudinal nerves are in close proximity but 

 the nerves do not form a continuous chain. The function of this nerve 

 has not yet been determined. 



3. THE ABDOMINAL GANGLIA AND NERVES. 



There are seven ganglia in the abdomen, situated along the 

 median line of the venter above the ventral muscles and beneath the 

 alimentary canal and ventral diaphragm. The ganglia, as a rule, are 

 in the anterior third of their respective segments. The first and last 

 ganglia, however, are usually situated on the suturai line between the 

 segment which they respectively innervate and the one anterior to it. 

 The lengths of the connectives are fairly uniform. Those between the 

 sixth and seventh segments are somewhat shorter than the others 

 owing to the moving forward of the last ganglion; for the same reason 

 those between the third thoracic ganglion and the first abdominal 

 are somewhat shorter than the others. 



The pairs of abdominal connectives are united throughout five- 

 sixths of their length and separate slightly near the posterior end before 

 entering the ganglion. The fusion is usually solid, there being no 

 indication of the duplex character of the fused portion. The last pair 

 of connectives are sometimes united throughout their entire length, 

 but in this case, a short crease on the' dorsal side of the posterior end 

 of the connectives marks the division between them. 



Nerves of the First Abdominal Ganglion. (Figs. 1 and 

 2. I.) Nerve A originates from the anterior end of the lateral border 

 of the ganglion and runs in a lateral direction. The first branch a is 

 very minute and is not always present. It runs forward and unites 

 with the transverse nerve. Branches b and c both run backward 

 and innervate ventral recti and upper oblique muscles. Before 

 reaching the tracheal trunk, nerve A sends a second branch to the 

 transverse nerve. After crossing the trachea it again unites with the 

 transverse nerve either directly or by means of a short cross nerve. 

 In the dorsum the nerve branches profusely sending branches to the 

 integument and muscles. 



