24 Journal New York Entomological Society. l Vo1 - xxvu. 



median cephalic trachea divides to form its two main tracheae run- 

 ning to the head a ventral branch is given off which unites with the 

 inferior thoraco-cephalic trachea (Plate III, Fig. i;tc). The thoraco- 

 cephalic trachea (tc) enters the head just beneath the body of the 

 tentorium (see Fig. i and Fig. 14), then curves laterally, giving off 

 branches to the labium, maxillae, and mandibles, while the main tube 

 continues on and ends at the plexus situated at the junction of the 

 anterior tentorial arm and external chitin (Fig. 5). 



The following tubes constitute the more important tracheae found 

 in the head region. 



The ophthalmic trachea (Plate III, Fig. 5, ot) surrounding the com- 

 pound eye gives off numerous branches which supply the optic 

 ganglia. A large sac-like tube (gt) originates from the ventral por- 

 tion of the ophthalmic trachea and runs ventrally beneath the gena 

 to the anterior tentorial plexus (Tp) previously mentioned. Con- 

 necting these tentorial arm plexuses is a large transverse dilated 

 trachea which passes in the front of the head just above the junction 

 of the clypeus and frons (Fig. 6). From this tube, branches are 

 given off to the clypeus and labrum. Medially this transverse tube 

 gives off a dorsal dilated air sac which supplies the front of the head 

 and connects dorsally with both the ophthalmic and superior cephalic 

 tracheae. 



All the above mentioned tracheae receive air through the large 

 chamber of the first thoracic spiracle, with the exception of the 

 thoraco-cephalic trachea which receives air from the first, second and 

 third spiracles (/, 77, III ) in a more or less indirect manner. 



(b) Thoracic Tracheal System. 



The thorax contains many muscles all of which must be intimately 

 supplied with oxygen. This necessitates a large number of tracheae 

 whose arrangement is very complicated. The tracing of this system 

 becomes very difficult because upon removing a muscle to expose the 

 tracheae beneath, a large number of the connections between the 

 tracheal tubes of each layer are destroyed. 



The tracheae situated in the median sagittal plane will be discussed 

 first (Plate I, Fig. 1). The other figures (Fig. 2 and Fig. 3) are 

 drawn looking from within and removing one muscle layer at a time 

 until the last layer is reached, which is drawn both from within (Fig. 



