340 
Psyche 
[December 
the leg, it resembles the transverse tracheae to which I gave 
even numbers, and is the trachea which I designated as 2-a. 
The middle of the three branches runs on the inner sur- 
face of the muscle layer and sends branches to the pro- 
thoracic and suboesophageal ganglia, and to the muscles. 
The hindmost branch also runs on the inner surface of 
the muscle layer. It crosses the muscles, and bending ven- 
trally sends a branch to the prothoracic leg. 
The middle and hindmost branch, taken together, are, 
in their position and distribution so similar to trachea 3 
that I believe them to.be at least analogous to the tracheae 
with uneven numbers. Therefore I have numbered them 
together as branches of trachea 1-a. 
The next large branch from the main trachea runs largely 
across the dorsal surface of the muscles inside of the head, 
apparently supplying them. 
A small branch runs from the main tracheal system to 
the supraoesophageal ganglion. 
Just in front of this ganglion, and lying so that the main 
tracheal branch is just behind the body of the tentorium, 
is the first transverse trachea described above. There are 
two branches from this trachea extending backward. Some- 
times they go to the suboesophageal ganglion (Fig. 18), 
and sometimes they end in the nerve cords anterior to it. 
In sending these branches to the nervous system, this 
trachea resembles tracheae 2, 4, etc., but in lying above the 
neural commissures it differs from them. 
In describing the main tracheae from the spiracle I said 
that two large branches extend toward the head. From one 
springs the half of the dorsal transverse system forming 
the diamond. From the other spring branches 2-a, 1-a, 
the trachea to the supraoesophageal ganglion, and the first 
transverse connection, I believe that these branches indi- 
cate that this trachea is the main longitudinal trunk, and 
not the one giving rise to the diamond. For, as will be 
shown, the transverse tracheae supplying the ganglia of the 
body segments posterior to the prothorax always spring 
directly from the main trunk near the spiracle. If it is 
true that the anterior arm of the tentorium is formed from 
an invagination of the body wall representing the spiracle 
