294. Annals Entomological Society of America  [Vol. XIV, 
surrounded by a row of sete which in most cases is limited by 
the extent of the chitinization. In specific cases, short, hook- 
like sete or stout spines replace the normal bristles. In seg- 
ment six the posterior angles of the tergum possess two spiracles, 
orifices of a common trachea. On account of their position 
they are conveniently designated as the anterior and posterior 
spiracles. In segment six and seven the posterior angles 
of the tergum may become accentuated by a thinning of the 
chitin across those regions and the isolation of chitinous areas 
bearing numerous sete. In such cases these areas have been 
designated as the accessory pieces. 
The ventral plate (sternum) likewise varies in degree of 
chitinization, though not to the extent of the tergum. In 
segments six and seven the sternum usually consists of a long 
strip of chitin that tends to become indeterminate cephalad, 
sometimes this plate is limited to areas adjoining the caudal 
margin. The setz border the caudal margin of the sternum in 
a row or are separated into two lateral groups. Similarly 
they are too replaced by stiff stout spines in certain cases. 
In segment eight the sternum is divided into two chitinous 
halves, more or less bilaterally symmetrical and known as the 
sternites. In general structure they present a hingelike appear- 
ance, overlapping the junction of the fourth intersegment with 
the conjunctiva of the eighth segment. In Chortophila cinerella 
Fall, and parva R-D, the sternites attain the whole length of the 
segment as two narrow rods of chitin. The sete are to be 
found toward the caudal extremity, scattered irregularly, 
among which are often two of greater size and strength. 
The lateral conjunctive of segments six, seven and eight 
are situated in a similar position to that of the segments of the 
abdomen, i. e., it consists of that part of the less chitinized 
cuticula, which is found between the sternum and tergum. 
Similar to the intersegments the conjunctive may be smooth or 
spinulose, or partly smooth, partly spinulose. The spinules 
may be arranged in indefinite transverse striz or scattered 
irregularly throughout the membrane. The cephalic and 
caudal extents of the conjunctive are limited by the annulations 
of the segments. 
Segment nine is modified to form the upper and lower lips of 
the anus The tergum or upper lip is composed of a single 
chitinous piece, hemispherical or scoopshaped, which is known 
—_—s-_ = 
