March, 1919.] VlNAL: CAROLINA LOCUST. 29 



the genital organs (x). Anteriorly this system ends in small air 

 sacs situated in the first abdominal segment. 



Alimentary Canal Tracheal System. — (Plate V, Fig. 16.) With 

 the exception of a short branch of / 2b" (Plate III, Fig. i), which is 

 contiguous to the proventriculus, all of the tracheal tubes connecting 

 with the alimentary canal arise from the abdominal spiracles. From 

 spiracle 3 two air tubes run to the alimentary canal, one connecting 

 with the lateral alimentary trachea (Ir), the other connecting with 

 the superior alimentary trachea (sp). These longitudinal tubes, the 

 lateral and superior alimentary tracheae, are situated between the 

 coecal pouches and are continued posteriorly in a more or less indefi- 

 nite manner until opposite spiracle 8, where they unite to form a 

 single tube which connects with spiracle 10. The superior alimen- 

 tary trachea gives off many branches between its connections with 

 spiracles 6 and 8, which enter the reproductive organs. The two 

 branches given off by spiracle 3 supply the dorsal and lateral sides 

 of the alimentary canal in the vicinity of the cceca, while the single 

 branch given off from spiracle 4 supplies only the ventral portion of 

 this region. From spiracles 5, 6, 7 and 8 two branches are sent to 

 the alimentary canal, one, a dorsal tube connecting with the superior 

 alimentary trachea (sp), the other a ventral branch supplying the 

 ventral side of this canal. Spiracle 9 supplies a ventral tube run- 

 ning beneath the ileum, and a dorsal dilated tube which connects with 

 the ileal plexus (Ip). From spiracle 10 many branches arise which 

 supply tracheae to the digestive canal and to the muscles of the repro- 

 ductive organs. The most important trachea given off by this spi- 

 racle is a dilated tube which connects with the ileal plexus (Ip). 



In Plate V, Fig. 16, the alimentary tracheal system has been drawn 

 only for the left side. On the right side the air sacs which occur 

 in the abdomen have been figured. These are also shown in Plate 

 IV, Fig. 8. 



The air sacs on each side of the abdomen are connected by a longi- 

 tudinal tube which joins posteriorly the ileal plexus (Ip). This 

 plexus, then, consists of six more or less dilated tubes which unite 

 just anterior to the rectum and above the ileum. 



In Fig. 16 only the right half of the rectum has been drawn in 

 order that the origin of the tracheae which appear on it may be better 

 shown on the left side. 



