742 THE GENERATIVE 



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., ,;;.,) are a 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- 

 t< rior gonapophysis rxhil>its a group of minute sensory setae. 



