March, 1919.] VlNAL: CAROLINA LOCUST. 31 



tc — Thoraco-cephalic trachea. 

 Tp — Anterior tentorial arm plexus. 



(b) Thorax. 



ale — Trachea to alimentary canal. 

 g — Trachea connecting with I— lie (Fig. 3). 

 7 i 7 2> 7 3 — Pro-, meso-, and metathoracic leg trachea. 

 Up — Second spiracular plexus. 

 tc — Thoraco-cephalic trachea. 

 w — Trachea connecting with air sac F. 

 Trachea? found between the thoracic muscles are designated by combining 

 two Roman numerals. I-II-b = a trachea connecting spiracle I with spiracle 

 II. The letters a, b and c denote the muscular layer in which these tubes 

 appear. Fig. 1 = layer a ; Fig. 2 = layer b ; Fig. 3 = layer c. 



(c) Abdomen. 



da — Dorso-abdominal trachea. 

 Ip — Ileal plexus. 

 ir — Lateral alimentary trachea. 

 sp — Superior alimentary trachea. 

 spt — Spiracular trachea. 

 va — Ventro-abdominal trachea. 

 x (Fig. 9) — Trachea supplying air to reproductive organs. 

 7-Xor3-io — See Spiracle Terminology. 



Explanation of Plates III-V. 



Fig. 1. Median sagittal section of head and thorax. 



Fig. 2. Longitudinal dorsal muscles of the thorax removed from Fig. 1 

 to show the dorsal tracheae lying beneath. 



Fig. 3. Muscular layer shown in Fig. 2 removed to show the tracheae and 

 muscles in the next layer. This is an internal view of the lateral thoracic 

 muscles. 



Fig. 4. Situation of the spiracles. 



Fig. 5. Side view of head showing tracheae. 



Fig. 6. Front view of head showing tracheae. 



Fig. 7. External view of lateral muscles shown in Fig. 3. 



Fig. 8. Sagittal section of the abdomen with the digestive canal removed 

 to show the abdominal air sacs, dorsal and ventral tracheal systems together 

 with the spiracular trachea. 



Fig. 9. Ventral abdominal tracheal system. 



Fig. 10. Dorsal aspect of head showing tracheae of this region. 



Fig. 11. Internal view of the first thoracic spiracle situated on the right 

 side of the body. 



Fig. 12. Internal view of the second thoracic spiracle situated on the 

 right side of the body. 



Fig. 13. Internal view of the abdominal spiracles situated on the right 

 side of the body. 



