THE ADULT DRAGONFLY 19 
on the ventral side. In copulation she is swung beneath the suspended 
body of the male into an inverted position, the reverse of his own, his 
caudal appendages still holding her in front. Her genital segments 
are grasped and held by the hamules of the male during the transfer 
of the sperm. 
The form of hamules and caudal appendages in the male, and of 
the plate that covers the genital opening of the female is shown in 
many figures on succeeding pages of the book. 
In the Anisoptera the caudal appendages of the male are three; 
a pair of decurved superiors (cerci), and a single median upcurved 

al ah ph v 
c D 
Fic. 8. Diagrams illustrating principal types of male genitalia. A and 
B, end of abdomen; A in Zygoptera, B in Anisoptera; s, superior, 7, in- 
ferior appendages. 
C and D, genitalia of second segment; C in Libellulidae, D in Gom- 
phinae; al, anterior lamina; h, ah and ph, hamules (anterior and posterior); 
gl, genital lobe; v, vesicle. 
inferior appendage. Between these the top of the head of the female 
is grasped preparatory to a mating flight. On the second abdominal 
segment the genital cleft is guarded in front by an anterior lamina, 
and contains one or two pairs of hamules. Folded compactly between 
the hamules is a triple-jointed penis that belongs to the third segment, 
and is attached to a rather conspicuous vesicle at the front end of the 
sternum of that segment. 
In the Zygoptera the caudal appendages of the male are two pairs: 
a pair of superiors (cerci) as before, and a pair of upcurving inferiors, 
developed lower down and not homologous with the single inferior of 
the other suborder. That appendage is represented in this suborder 
by a low rudimentary protuberance between the bases of the superiors. 
The genitalia of the basal segments in the male differ chiefly in that 
the penis belongs to the sternum of the second abdominal segment, 
