96 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. IO3 



The basal apparatus of the sting presents on each side three plates 

 (fig. 31 A). Uppermost is the large quadrate plate (Qd), which, 

 as already explained, is a lateral remnant of the ninth abdominal 

 tergum. Below the quadrate plate, and partly overlapped by its 

 lower margin, is a horizontally elongate oblong plate (Ob). Above 

 the anterior end of the oblong plate and before the quadrate plate 

 is a small triangular plate (Tri), articulated by the dorsal angle of 

 its base (c) with the quadrate plate, and by the lower angle (d) with 

 the upper edge of the oblong plate. The triangular plate and the 

 oblong plate represent, respectively, the first and the second valvifer 

 of the ovipositor of other insects. Projecting from the distal end of 

 each oblong plate is a long, soft appendage (Sh) ; the pair of ap- 

 pendages clasp the shaft of the retracted sting and thus form a sheath 

 for the latter. Between the lower edges of the oblong plates is a 

 deeply concave membranous fold, which is the unsclerotized ventral 

 wall of segment IX; it projects posteriorly as a free lobe {IX. V) 

 when the shaft is depressed. 



The shaft of the sting consists of three closely appressed parts 

 mutually tapering to a point (fig. 31 A). The unpaired upper com- 

 ponent is the stylet (Stl), the paired lower elements the lancets (Let). 

 The lancets are the so-called first valvulae of an ovipositor, the 

 stylet represents the united second valvulae. Proximally the stylet 

 is expanded in a bulblike enlargement (bib), which contains a cavity 

 open below and continued as a ventral groove to the end of the 

 stylet. The curved arms that unite the shaft with the supporting base 

 of the sting are composed each of two parts. The first (ir) is a 

 proximal ramus of the lancet, connecting the lancet with the apical 

 angle (b) of the triangular plate (Tri) ; the second (2r) is a cor- 

 responding ramus of the stylet connecting the base of the stylet bulb 

 with the anterior end of the oblong plate (Ob). The slender lancets 

 are held close to the under surface of the stylet by grooves that fit 

 over tracklike ridges of the latter (G), and the same interlocking 

 apparatus is continued upon the basal rami, the first ramus being 

 grooved to its upper end (D, ;'), the second having a ridge on its 

 convex margin (C, i). The lancets are thus able to slide freely back 

 and forth on the under side of the stylet. Between the stylet and the 

 lancets is the poison canal of the sting (G, pc), which expands 

 proximally into the cavity of the bulb, and here receives the poison 

 liquid from the great poison sack (A, PsnSc), or reservoir of the 

 poison glands, which opens into the base of the bulb. Each lancet 

 bears on its proximal part a valvelike lobe (D, Vlv), the two lobes 

 projecting side by side into the cavity of the bulb, where they serve 



