1029] 
Tracheal System of Pyrausta nubilalis 
341 
of the mandibular segment (Comstock and Kochi 1902), 
it is not unreasonable to imagine that the first transverse 
tracheae indicate, at their point of origin, the positions of 
the branchings from a spiracle, and that it is here that the 
main longitudinal trachea ends, rather than at the pro- 
thoracic spiracle. 
From just in front of the base of the transverse trachea 
two tracheae of about equal size run forward. The inner 
one ends in two short branches, one to the maxilla, and one 
to the labium. The outer trachea sends branches into the 
mandible, and a branch to the region of the base of the 
antenna. I was unable to trace this into the antenna. A 
small branch from the trachea to the supraoesophageal 
ganglion runs forward and joins one of the mandibular 
branches. 
The other tracheae arising from the prothoracic spiracle 
are the posterior branch going into the formation of the 
main longitudinal trachea, and a branch also running back- 
ward which joins the trachea to the posterior apex of the 
diamond. Branches also go from this backward running 
branch to muscles and fat bodies, and a branch divides into 
tracheae supplying the appendages of the mesothorax. 
Trachese to the Nervous System 
The tracheae to the supra- and suboesophageal ganglia, 
and to the prothoracic ganglion have been described. 
The mesothoracic ganglion is supplied with air by 
tracheae 2 and 3. Trachea 2 sends a branch backward to 
the ganglion, and trachea 3 sends one forward as described. 
Trachea 3 lies on the inner surface of the muscle layer 
and sends many branches to the muscles (Fig. 15). Its 
main branch runs around the edge of the muscle layer and, 
turning downward, extends into the mesothoracic leg. 
Trachea 5 differs from trachea 1 and 3 in that it does 
not connect with the corresponding trachea from the op : 
posite side. It sends branches to the muscles and its for- 
ward branch runs around the edge of the muscle layer, 
and turning downward, enters the metathoracic leg. It also 
