SEXUAL CHARACTERISTICS OF THELIA 59L 
each side of the ovipositor from a median rib toward the ventral 
border. Thelia uhleri has a pointed ovipositor with a trans- 
lucent area behind a diagonal rib near the tip. This seems to 
be a general characteristic of the Telamonini studied. Ovi- 
positors of parasitized Thelia are not only reduced in size, but 
they are more pointed at their distal ends than those of normal 
individuals. The chitinous ribs are reduced in size, and one 
may easily discern a thinner area near the tip on the ventral 
border. 
Thus both oedagus and ovipositor lose through parasitism 
characteristics specific for Thelia bimaculata. These specific 
characteristics of the genitalia must be recent acquisitions in 
the genetic make-up of this highly specialized form. They 
merely modify and add details to the gonapophyses, organs long 
established and rather stable in most homopterans. Whereas 
the genitalia of parasitized individuals retained the general form 
found in the tribe Telamonini, they lost their specific character- 
istics through the action of the parasites. 
7. AN ACCOUNT OF TWO SIGNIFICANT INDIVIDUALS 
Two extraordinary individuals, one captured in the summer 
of 1916 and the other in the summer of 1917, throw consider- 
able light on the relation of the gonads to the soma in Thelia, 
and are too important to omit even in this paper which deals 
mainly with the effect of the parasites upon external features of 
the host. 
The first individual was an adult parasitized male. The para- 
sites were of medium size, measuring 0.75 mm. from the post- 
cephalic region to the posterior end of the abdomen. Their 
mouth parts were not chitinized and the curved bodies of the 
parasites were enclosed in nutritive envelopes. However, the 
larvae had already exerted a marked influence on the host. 
The pronotum (fig. 48) showed considerable change in colora- 
tion toward the female condition. The bright yellow was absent 
from the vitta, and the melanic pigment over the rest of the pro- 
notum was no longer uniform and encroached upon the clear 
chitin of the vitta. The length of the pronotum was 11.90 mm., 
