98 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. IO3 



apparatus is shown in greater detail at C and E of figure 31, and the 

 action of the depressor muscles (ip/) on the shaft is diagram- 

 matically expressed at D and E of figure 32. Mesad of the fulcrum 

 each ramus of the stylet is continuous with the bulb by a slender, 

 flexible connection. The opposite movement of the shaft, by which 

 it is again turned upward and ensheathed between the oblong plates 

 and their distal appendages, is effected by a pair of slender muscles 

 stretched from the second rami to the fulcral lobes of the bulb (figs. 



31 B, C, 32 C, D, ip6), the insertion points of the muscles being 

 sufficiently beyond the fulcral points to afford a short leverage on the 

 shaft. 



The movements of the lancets accomplish the penetration of the 

 tip of the shaft into the victim, and the injection of the poison into 

 the wound. They are produced by two pairs of large muscles in the 

 basal apparatus that aft'ect primarily the quadrate plates, and 

 secondarily the triangular plates and the attached lancets. The muscles 

 of one pair consist each of two large bundles of fibers (figs. 31 B, 



32 C, ip8) attached posteriorly, one laterally the other mesally, on 

 the upper apodemal part of the quadrate plate, and anteriorly on the 

 anterior end of the oblong plate. The muscles of the other pair (ipp) 

 are attached anteriorly by broad, spreading bases on the inner surfaces 

 of the quadrate plates, and posteriorly on the posterior ends of the 

 oblong plates. The alternate contraction of these two muscles on each 

 side pulls the corresponding quadrate plate first forward and then 

 backward, relative to the oblong plate ; the movements of the quadrate 

 plate are transmitted to the triangular plate (fig. 31 A, Tri) by the 

 connection of the former with the upper basal angle of the latter (c) ; 

 the triangular plate, in turn, rotates on its ventral articulation (d) 

 with the oblong plate, and the final result is that the alternate up-and- 

 down movement of the apical angle (b) of the triangular plate is 

 transmitted to the attached ramus of the lancet (ir), which gives the 

 lancet itself a back-and-forth movement on the stylet. The mechanism 

 is illustrated diagrammatically at F and G of figure 32. At F muscle 

 ipp, the retractor of the stylet, is contracted, the quadrate plate con- 

 sequently pulled backward, the apex of the triangular plate lifted, and 

 the lancet {Let) retracted by the pull on its basal ramus. At G muscle 

 ip8, the protractor of the lancet, is in contraction, the quadrate plate 

 is pulled forward, the triangular plate depressed, and the lancet pro- 

 tracted. In a living bee, as may be seen in a freshly extracted sting, 

 the movements of the quadrate plates appear as a rapid vibration, and 

 the two lancets have alternately opposite motions. 



