336 
Psyche 
[December 
cept, possibly, the first abdominal. There is one in the 
mesothorax, although that segment does not bear a func- 
tional spiracle. There is one in the head. 
The transverse trachea in the head lies in front of the 
supraoesophageal ganglion and just behind the body of the 
tentorium. The posterior arms of the tentorium pass above 
the trachea, close to its junctions with the main longitudinal 
tracheae. This transverse trachea lies above the commis- 
sures between the supra- and subcesophageal ganglia. 
(Fig. 8). 
Peterson (1912) describes and figures a cross trachea in 
the larva of the tomato-worm, Protoparce Carolina , lying 
above the commisures between the supra- and sub-oeso- 
phageal ganglia, but in the tomato worm this trachea crosses 
the suboesophageal ganglion. In Pyrausta nubilalis it lies 
well in front of the ganglion. Peterson says nothing about 
the relation of this trachea to the tentorium, but from his 
figure, the trachea must lie well behind it. 
The next cross trachea, which I have numbered 2-a, is 
a secondary branch. The primary branch from which it 
springs comes from the main trachea just after it leaves 
the prothoracic spiracle and its other branches will be de- 
scribed later. 
Trachea 2-a runs on the outside of the muscle layer, and 
beneath the central nervous system. 
In the prothorax there is a transverse system of tracheae 
dorsal to the alimentary tract. These tracheae are ar- 
ranged in such a manner that I term the system the 
diamond . (Fig. 9). 
A large branch arises from the thoracic spiracle. It runs 
forward a short distance, then branches into two good sized 
tracheae, the larger being in front. Each of these branches 
meets a corresponding branch from the opposite side, and 
the double Y thus formed gives the shape that justifies my 
name for the arrangement. From the forward apex of 
the diamond branches go into the head. From the posterior 
apex a long branch goes backward and joins a branch from 
the main trunk that runs backward from the prothoracic 
spiracle Thus, counting each branch separately there are 
