742 THE GENERATIVE ORGANS. 
The paraphalli are continued forwards, one on each side of 
the organ, as long curved hooks, which articulate with the 
cornua of the hypophallus. 
These hooks probably rest in the pouches on either side of 
the genital spine of the female during copulation, and the 
hollow on the ventral surface of the hypophallus rests on the 
spine itself. If this is the case, the orifice of the penis would 
be in immediate relation with the ducts of the receptacula 
seminis. 
Mr. Hammond has shown me a number of beautiful draw- 
ings of the utero-vaginal tube and external generative organs 
of Tipula. In this insect the utero-vaginal tube is very long, 
so that the ducts of the receptacula are at a considerable 
distance from the vulva; and the penis is also greatly pro- 
longed by the exsertion of a long curved chitinous flagellum, 
which is apparently a prolongation of the ejaculatory duct. 
The length of this flagellum corresponds with the length of the 
utero-vaginal tube. The penis itself is very short, and has no 
salient armature. Copulation is effected by the highly complex 
gonapophyses, and the flagellum of the penis.is brought into 
immediate relation with the receptacula. 
In the Blow-fly the act of copulation has been rarely ob- 
served, and for many years I never saw this insect in coitu. 
Lately I have seen it several times. It takes place in the sun- 
light in the early morning. The male is above the female. 
These insects never copulate on the wing. They are very shy 
when united, and immediately separate when captured, so that 
I have been unable to ascertain the position of the parts during 
copulation. 
The Posterior Gonapophyses (PI. LI., ¢,) area pair of unjointed 
hollow palp-like organs at the root of the penis, one on either 
side of the azygos spine. They articulate with the posterior 
part of the saddle of the paraphalli by distinct joints. Each 
exhibits a curved process at its base, which articulates with a 
similar process arising from the proximal edge of the corre- 
sponding anterior gonapophysis. The extremity of the pos- 
terior gonapophysis exhibits a group of minute sensory sete. 
