EXTERNAL ANATOMY OF INSECTS. 391 



two grooves, in which the Terebella or Spicula 

 play a . 



E Terebella (the Terebella:). 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 b . 



5. Aculeus (the Sting). The above instrument, when 

 fitted for an offensive weapon c . It includes, besides 

 the Valvce and Vaginula before defined, the Spicula. 



A Spicula (the Darts). The proper stings which inflict 

 the wound : retractile within the sheath, externally ser- 

 rulate at the apex d . They include the Retinaculum. 



a Retinaculum (the Retinaculum). A minute horny 

 moveable scale or plate with which the darts are fur- 

 nished, which prevents their dislocation by being 

 shot forth too far e . 



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, Caudula?, Fila, Mam- 

 nndce, Papilla;, 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. Forficida. 



2. Forfex (the Forfex). A pair of anal organs, which 



open or shut transversely, and cross each other f . 

 Ex. Male of Raphidia Ophiopsis. 



* Plate XV. Fig. 20. G'. 



b Ibid. Fig. 20, 21 ; and XVI. Fig. 1. H". 



c Rirby Mon. Ap. Angl. i. t. xii. Apis **. e. 1. neut.f. 23 — 25; and 

 t. xiii./. 27, 28. 



-i Ibid. t. xiri./. 30, 31. e Ibid. a. 



* Plate XV. Fig. 12. L". 



