218 ANATOMY. 



the female, bent from below upwards, but from above downwards, so 

 that its apex is turned towards the venter. This point is broader than 

 the upper part, and apparently armed with barbs ; consequently, during 

 copulation this spine of the penis must penetrate the ovipositor of the 

 female if impregnation is to follow. This insertion, however, is only 

 made possible by the hook-shaped bend of the penis, and much faci- 

 litated when the male sits upon the female. The Cicada actually thus 

 copulate, but as their connection lasts long, and the constant weight of 

 the male would be oppressive to the female, the male descends and sits 

 by her side, when she reposes. In some genera of the Cicada, the 

 pronoturn of which is decorated with processes and excrescences, which 

 project beyond the abdomen (Combophora, Centrotus), the first act of 

 copulation can only take place in this position of both sexes by the side 

 of each other, they have probably therefore a laterally bent penis for 

 this purpose, thus adapted like the downward bent one of the pre- 

 ceding. 



We must lastly notice the male sexual organs of the Libellulee, as 

 the erroneous opinion has long been held that they were not placed at 

 the end of the abdomen, but at its base. This very naturally ori- 

 ginated from the observation that the male flew about with the female, 

 retaining her anal extremity by means of clasps affixed to the base of 

 the abdomen, and at the same time held her in the neck by the valves 

 of its tail, apparently occupied in copulation. But if we closely exa- 

 mine the economy of these insects we shall speedily observe that males 

 fly at sitting females and rapidly copulate with them, like the flies. 

 The preceding is merely an expression of mutual inclination which 

 announces itself by the male suddenly seizing the female by the neck 

 in the air, and thus flying off with her, whilst she, if willing to respond 

 to this attention, bends up her anal end to the male, and allows herself 

 to be there seized by the hooks lying at the base of the abdomen ; but 

 if not pleased with his caresses she does not bend her body up to him, 

 but hangs it freely and unparticipant downwards, and remains like a 

 prisoner attached to his chain. 



The following is an accurate description of the male sexual organs, 

 as well as of the prehensile organ at the base of the abdomen. 



We observe in the ventral plate of the ninth abdominal segment an 

 aperture closed by two valves (PI. XI. No. 3. f. 9. d). If these valves 

 are removed we detect a small, delicate, horny ring, which surrounds 

 the aperture of a short membranous cylinder ; this cylinder is the penis. 



