390 EXTERNAL ANATOMY OF INSECTS. 



v. Anus (the Anus). The termination of the abdomen, 

 consisting of the two last segments. It includes the 

 Podex, Hypopygium, Cuius, Ovipositor, and Appen- 

 dices. 



1. Podex (the Podex). The last dorsal segment of the 



abdomen a . 



2. Hypopygium (the Hypopygium). The last ventral 



segment of the abdomen b . 



3. Culus (the Cuius). The orifice at the end of the 



anus. 



4. Ovipositor (the Ovipositor). The instrument of 



oviposition, by which the insect conducts the eggs 

 to their appropriate nidus, and often bores a way to 

 it ; the same instrument is by some genera used as 

 a weapon of offence, when it is called the Aculeus c . 

 It includes the Unci, Tubulus, Valvce, Vaginula, and 

 Terebellce. 



A Unci (the Unci). Two pair of robust organs, the 

 upper incurved and the lower recurved, with which 

 the anus of Locusta Leach is furnished d . 



B Tubulus (the Tubulus). A tubular ovipositor, con- 

 sisting of several pieces often retractile within each 

 other, like the tubes of a telescope e . 



C Valv^: (the Valves). Two lateral laminae, often coria- 

 ceous, by which the ovipositor when unemployed is 

 covered f . 



D Vaginula (the Sheath). A corneous case, with 



* Plate VIII. Fig. 5, 15. K '. b Ibid. Fig. 6, 15, 18. L' . 

 « Plate XV. Fig. 18-22; and XVI. Fig. 1—3. 



* Plate XV. Fig. 18. E . 



' Plate XV. Fig. 22; and XVI. Fig. 2 3 3. 

 f Ibid. Fig. 20, 21 ; and XVI. Fig. \. F\ 



