66 
Psyche 
[April 
Abdomen. PL II, figs. 9-14. PI. Ill, fig. 15. The abdomen 
in both sexes is of a bright orange color and is destitute of macro- 
chsetse. It is sparsely clothed, however, with short black hairs. 
Seven pairs of spiracles (sp) are present, borne at the lateral 
margins of the tergites (ti, t 2 ), etc.). Those of the sixth and 
seventh segments are hidden beneath the posterior edge of the 
fifth tergite (ts). The tergites of the first and second segments 
are fused, the fusion being denoted by an area of weaker chitin, 
which is demarked in the figures by a pair of dotted lines between 
ti and t 2 . The adventitious suture (as) in the first tergite, men- 
tioned by Young, is readily seen. 
The tip of the abdomen in the female is wholly black, thia 
coloration including the fifth tergite and in some individuals ex- 
tending further forward to include part of the fourth tergite. 
The terminal abdominal segments of the male in specimens 
examined by the writer were in no case wholly black, although 
ts and te were darker than those preceding. 
Genitalia.^ PI. II, figs. 13-14; PI. Ill, fig. 15. In both sexes the 
segments beyond the fifth abdominal may truly be called genita 
segments. In the male these segments curve downward and come 
to lie beneath the fifth tergite. In the female those beyond the 
fifth are telescoped when at rest, being 'extended for oviposition. 
In the male the fused tenth and eleventh tergites, which 
are ventral in position, act as a cover for the oedeagus (oe), 
being tucked beneath the edge of the fifth sternite (ss) when at 
rest. When the oedagus is extruded, however, this flap lifta 
up, allowing the ninth sternite (s,) to push forth. This latter 
segment is very much modified. Its fused cerci are median in 
position and form the oedagus, a very complicated structure 
which encloses the membranous penis. At the base of the 
oedagus are seen two pairs of lateral projections, called gono- 
pophyses (go), the inner pair of which are hyaline. They are 
well-chitinized, however, feeling hard to the touch of a dis- 
secting needle. At the base of the oedagus the ninth sternite is 
^The writer has based his description of the genitalia largely on the 
condition of these structures in generalized insects. It is apparent that the 
study of a series of dipterous genitalia may reverse some of his decisions re- 
garding the true character of the parts. 
