34-S G. G. SCOTT. 



the malpighian tubules and furnish the greater tracheal supply 

 to the stomach. 



Lateral System. - - At the posterior origin of the ventrals there 

 arises also the lateral tracheae (Figs. I and 2, LAT). These 

 run anteriorly lateral to the alimentary tract and near the outer 

 lateral edges of the abdominal walls. The laterals run forward 

 decreasing in size and join the metathoracics just beyond their 

 origin from the dorsals. From the lateral trachea a branch runs 

 out externally (Figs. I and 2, E AB} to each of the first six ab- 

 dominal segments supplying the muscles which assist in the com- 

 pression of the abdomen. Adjacent to these tracheae others arise 

 from the upper face of the lateral and run to the dorsal part of 

 each segment (Fig. I, S AB}. Then a third set of tracheals 

 originate from the laterals along with the others. These the seg- 

 mentals (Fig. 2, scg) pass ventrally along the hinder margin of 

 each segment sending branches forwards the width of the seg- 

 ment. Finally a fourth set of tracheal tubes arise from the lat- 

 erals in each segment, the inferior abdominal (Fig. 2, I AB} so 

 named because they pass below the alimentary tract. They 

 bifurcate a short distance from their origin from the laterals. 

 The anterior branch (Fig. 2, GN} supplies the near half of the 

 abdominal ganglion of that segment. The posterior branch (Fig. 

 2, SP} runs out to the abdominal spiracle of that segment. In 

 the nymph as before described these spiracles are closed yet the 

 tracheal distribution to them is clear. 



The first of the ganglionic tracheoles sends a branch forwards 

 to the metathoracic ganglion and a branch back to the second 

 ganglionic trachea. The seventh abdominal ganglion and spir- 

 acle has a different supply receiving a branch from the posterior 

 continuation of the dorsal (Fig. 2, P C}. Near this arises another 

 trachea which with a similar one from the other side forms a net- 

 work in the posterior and ventral part of the body cavity. Only 

 the main features of it are shown in Fig. 2. 



The distribution to the thoracic ganglia is more complex. 

 Each of the thoracic ganglia receives on either side a branch from 

 the neural trachea (Fig. 2, NEUR). This trachea takes a some- 

 what tortuous course the length of the thorax alongside the 

 thoracic ganglia. It receives a branch from the prothoracic 



