THE BIoLOoGY OF THE CHRYSOPIDAE Waiaal 
seen to be made up of two prominent side lobes, which meet at their pos- 
terior extremity but are separated anteriorly (fig. 158, A). The very 
prominent oblong vulva is located between these lobes, at their base. It 
has a sharply defined border and is not covered with the prominent hair 
seen on the lobes. A suture running from in front posteriorly divides it 
into two equal parts. Both the gelatinous stalk-forming substance and 
the egg issue from this opening at oviposition. 
A ventral view of the end of the abdomen of a male of C. oculata 
shows marked differences from that of the female. The two lateral 
lobes stop short of the midline and a prominent ventral plate extends 
between the two borders (fig. 158, B). This ventral plate has a prominent 
depression extending across it near the middle. There is another lesser 
depression, parallel to this and a little posterior to it. This ventral 
plate extends practically as far eaudad as the lateral lobes. The genital 
opening is within the extreme end of the abdomen, above the ventral 
plate, and the anus opens above it. In side view the abdomen ends 
squarely, in contrast with that of the female, which has a rounded end, 
the dorsal part being longer than the ventral. The depressed button- 
like cireular areas bearing the short, peculiar setae occur in the males 
as well as in the females, one on each side near the dorsum. 
Sexual dimorphism 
In addition to the genital differences, there is a striking sexual 
dimorphism in Meleoma signoretti. The male develops a prominent 
frontal horn, which bears a brownish ventral brush of hair (Plate 
LXXXIV, 6). In the male of M. slossonae there is a suggestion of this 
development and the surface of the front is somewhat irregular, but a 
definite horn is absent. McLachlan (1883-84) discussed a difference in 
the width of the costal area of the wings in the two sexes of Chrysopa 
flava. 
Copulation 
Copulation has never been described for the Chrysopidae. It has 
been observed several times in Chrysopa oculata and C. nigricornis dur- 
ing these studies. As a typical case, copulation of C. oculata observed 
under a binocular on June 26, 1916, may be described. About half a 
dozen pairs of adults of C. oculata emerged on June 24. They were put 
in a battery jar, which was then placed upside down over a small plant 
infested with aphids. At about 4.30 p. m. on the 26th, several females 
appeared to be chasing the males about. When they came near each 
other, both the males and the females began to jerk the abdomen upward 
