1. PODEX (the _Podex_). The last dorsal segment of the abdomen[1127].
2. HYPOPYGIUM (the _Hypopygium_). The last ventral segment of the abdomen[1128].
3. CULUS (the _Culus_). 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_[1129]. It includes the _Unci_, _Tubulus_, _Valvæ_, _Vaginula_, and _Terebellæ_.
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[1130].
B TUBULUS (the _Tubulus_). A tubular ovipositor, consisting of several pieces often retractile within each other, like the tubes of a telescope[1131].
C VALVÆ (the _Valves_). Two lateral laminæ, often coriaceous, by which the ovipositor when unemployed is covered[1132].
D VAGINULA (the _Sheath_). A corneous case, with two grooves, in which the _Terebella_ or _Spicula_ play[1133].
E TEREBELLÆ (the _Terebellæ_). Instruments by which the insect saws or bores a passage for its eggs to the place in which her instinct directs her to deposit them[1134].
5. ACULEUS (the _Sting_). The above instrument, when fitted for an offensive weapon[1135]. It includes, besides the _Valvæ_ and _Vaginula_ before defined, the _Spicula_.
A SPICULA (the _Darts_). The proper stings which inflict the wound: retractile within the sheath, externally serrulate at the apex[1136]. They include the _Retinaculum_.
a RETINACULUM (the _Retinaculum_). A minute horny moveable scale or plate with which the darts are furnished, which prevents their dislocation by being shot forth too far[1137].
vi. APPENDICES (the _Appendages_). Other instruments and organs, with which the anus of various insects is furnished. They include--the _Forceps_, _Forfex_, _Furca_, _Styli_, _Foliola_, _Flosculus_, _Caudulæ_, _Fila_, _Mammulæ_, _Papillæ_, and _Siphonuli_.
1. FORCEPS (the _Forceps_). A pair of anal organs that open and shut transversely, and _meet_ at their inner margin, or at the apex. Ex. _Forficula_.
2. FORFEX (the _Forfex_). A pair of anal organs, which open or shut transversely, and _cross_ each other[1138]. Ex. Male of _Raphidia Ophiopsis_.