STRUCTURK AXD BIOLOGY OF SCHIZONEURA LANIGERA. 685 
line the dorsal branches from all except the prothoracic 
spiracles bifurcate, and join to form on each side of it 
a main dorsal longitudinal trachea (rZ. t.), Avhich extends 
beneath the dorsal integument in a zig-zag longitudinal 
course, from the prothoracic to the seventli abdominal 
spiracle. 
One of the divisions of the dorsal branch from each of the 
seventh abdominal spiracles passes inwards, and both fuse in 
the median line, thus connecting the two lateral divisions of 
the dorsal tracheal system. 
Several small bunches of trachete, which ramify over the 
reproductive organs and alimentary canal and aerate the 
dorsal longitudinal muscles, are given off from the dorsal 
longitudinal trachea. 
From the prothoracic spiracles a stout trachea {a. t.) passes 
anterioi-ly, and branching considerably, aerates the cephalic 
ganglia and muscles of the head, a branch passing to the 
antennai. 
Ventral Tracheal System. — The ventral tracheal 
branches from the abdominal spiracles pass inwards, more or 
less parallel to one another, along the ventral surface of the 
body, and with the exception of the branch from the first 
and last of these spiracles, bifurcate to form a zig-zag ventral 
longitudinal trachea [v. 1.) on each side of the median line 
as in the dorsal system, but in the former case this stout 
trachea only extends from the first to the last abdominal 
spiracles. 
The ventral tracheal branch from the seventh abdominal 
spiracle does not bifurcate, the two lateral divisions of the 
ventral system not being connected at the posterior end, as is 
the case in the dorsal system. 
Several small tracheae are given off from the ventral 
longitudinal trachea of each side, and pass inwards to aerate 
the internal organs and ventral bands of longitudinal 
muscles. 
A small trachea arises from the ventral branch near each 
spiracle. 
