136 MISSOURI BOTANICAL GARDEN. 
This basal and sculptured portion of the integument 
represents the part which is invaginated when the ovi- 
positor is withdrawn. The outer rods enter on either 
side of the walls of the anal joint, extending and at- 
tached to the tip of the vagina. This arrangement for 
the exsertion of the ovipositor is at once simple and admira- 
ble, the contraction of the muscles forcing out the inner 
rods and carrying with them the ovipositor, and also ex- 
truding the tip of the vagina. The flexible and extensile 
oviduct is contained within the hollow center of the horny 
sheath and is doubtless extruded by the contraction of the 
body walls. In the other two species of Pronuba here dealt - 
with the rods are rather stouter and relatively shorter than 
in yuccasella. 
This general internal structure of the female here de- 
scribed is common to all the three species of Pronuba so far 
known, but the receptaculum seminis and the radiate 
bodies contained in it are, as already stated, in none of 
them so large and conspicuous as in yuccasella. In P. syn- 
thetica they are about half as large, with the spicules stouter 
and straighter and reminding one of some stiff-spined 
Kehinid. In P. maculata they are yet smaller. The same 
general structures also obtain in Proxodus, with much modi- 
fication of the ovipositor, however, and the radiate bodies of 
the receptaculum are smaller and seem in some species even 
to be obsolete. In P. decipiens they are smaller in propor- 
tion to the size of the sac, which is itself much smaller and 
more elongate than in Pronuba yuccasella. The spicules, 
however, are relatively larger, though few in number. 
