186 PHILIP p. CALVERT. 



absent, but a posterior, backwardly and downwardly-directed process 

 (^genital lobe) arises from either side of 2, and between those of the 

 right and left sides, the vesicle of the penis lies. The hamules are 

 apparently for clasping the edges of the vulvar lamina during copu- 

 lation. The sheath of the penis and the genital lobes are protective 

 organs. 



The separation of the orifice of the duct of the testes and the intromittent 

 organ in the Odonata is not a unique occurrence in the animal kingdom. In 

 male spiders the common duct of the testes opens on the base of the abdomen, 

 while a pedipalp is modified to form the copulatory organ. So, also, among the 

 Cephalopods, one of the arms of the male is modified (hectocotylized arm) for 

 the purpose of introducing the spermatophores within the mantle of the female. 



The reproductive organs of the female, the ovaries, are also paired 

 and occupy the same relative position as the testes; when function- 

 ally active, they extend forwards even as far as into the hind part 

 of the thorax. The ovarian tubes are very numerous and open into 

 an oviduct which unites with its fellow of the other side, in the eighth 

 .segment, to form the vagina. The vagina is provided with a dorsal 

 pouch — bursa copulatrix — and one or two receptacula seminis. In 

 Calopteryx, the receptaculum consists of two small lobes which unite 

 in a common canal ; in Agrion there is a single lobe ; in the Anis- 

 optera there are two receptacula, each with a distinct canal (Siebold 

 17). The external orifice of the vagina (vulva) is at the ventral 

 apex of 8. It may be simply an uncovered opening, or the posterior 

 extremity of the sternum of 8 may be prolonged as the vulvar lamina 

 to assist in ovi position. 



In the Agrionidse, the Aeschninre, the Cordulegastrinse, and some 

 Gomphiuse, the vulvar lamina is prolonged into two trough-like 

 plates, pointed at their distal extremities, with their concave faces 

 opposite each other so as to form a tube-ovipositor. Each plate con- 

 sists of two curved styles united side by side ; on the outside near 

 the apex are sopjc transverse ridges forming a file-like surface (Ag- 

 rionidfe, Aeschninse). In the Agrionidae, Aeschninse, and certain 

 Gomphiuse (Petalura), there lies on either side of this ovipositor a 

 chitinous piece — genital valve, derived from the sternum of 9. Ar- 

 ticulated to the apex of each genital valve is a slender, unjointed 

 process {valvular process) which terminates, in the Aeschninte and 

 the Gomphinse of the legion Petalura, with a small bundle of hairs; 

 in the Agrionidse these hairs are absent. The function of the genital 

 valves is probably to assist in the placingof the eggs within incisions 

 (made bv the pointed and roughened ends of the ovipositor) in the 



