ANATOMY AND PHYSIOLOGY 69 
Female Genitalia.—In Neuroptera, Coleoptera, Lepidoptera 
and Diptera the vagina simply opens to the exterior or else 
with the anus into a common chamber, or cloaca. Often, as 
in Cerambyx (Fig. 77) and Cecidomyia (Fig. 78) the attenu- 
Fic. 79. 
Ovipositor of Locusta. A, lateral aspect; B, ventral aspect; C, transverse section; 
c, cerci; d, dorsal valve; i, inner valve; v, ventral valve. The numbers refer to 
abdominal segments.—After Koztspe and DEwivz. 
ated distal segments of the abdomen serve the purpose of an 
ovipositor ; thus in Cecidomyiide, the terminal segments, tele- 
scoped into one another when not in use, form when extruded 
a lash-like organ exceeding frequently the remainder of the 
body in length. 
A true ovipositor occurs in Thysanura, Orthoptera, Odo- 
nata, Hemiptera, Hymenoptera and some other orders of in- 
sects. The ovipositor consists essentially of three pairs of 
valves, or gonapophyses—a dorsal, a ventral and an inner 
pair. The two inner valves form a channel through which 
the eggs are conveyed. In Locustide (Fig. 79) the three 
