126 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 89 



and between the three parts of the shaft is the poison canal of the 

 sting (r). In the bulb the canal expands to a large chamber, in which 

 lie a pair of pouchlike valves borne on the upper edges of the lancets 

 (A, Vlv) that serve to drive the poison liquid through the canal, 

 from which it makes its exit near the tip of the sting from a ventral 

 cleft between the lancets. The stings of the worker and the queen 

 differ principally in the size and form of the shaft. The shaft of the 

 queen is relatively larger and is strongly bent downward in the region 

 of the bulb ; when exserted, therefore, it curves ventrally or anteriorly 

 according to the position of the abdomen. The poison sac opens di- 

 rectly into the base of the bulb (fig. 42 C, PsnSc). The distal end 

 of the stylet is narrow but rounded, and in the worker it has three 

 pairs of very small lateral barbs on its dorsal surface. The tips of 

 the lancets are acute, and the terminal part of each lancet of the worker 

 is strongly serrate ventrally on its outer surface by a series of 10 

 retrorse barbs. 



The shaft of the sting is supported at its base on the rami of the 

 valvulae (fig. 41, rivl, r2vl). The two pairs of rami are widely 

 divergent as they curve upward to their connections with the valvifers 

 {iVlf, ^Vlf). A membrane stretches between the rami of the second 

 valvulae. The two rami of each side are united by a groove-and-ridge 

 connection continuous with that on the shaft (fig. 42 E), but since 

 the ramus of the first valvula lies against the outer surface of the 

 ramus of the second valvula (fig. 41), the groove of the first valvula, 

 which follows the dorsal edge of the lancet (fig. 42 A, d) , goes over 

 to the inner face of the ramus {d'). 



In order to understand an important point in the mechanism of the 

 sting it will be necessary to give close attention to certain details of 

 structure at the base of the bulb. Each second valvular ramus is rather 

 broad (fig. 42 B, r2vl) and presents a rounded lobe (w) near its 

 lower end. The direct union of the ramus with the bulb is a narrow 

 sclerotic bar {x), but laterad of it a hooked process {y) from the 

 base of the bulb makes a very fine connection {s) with the lobe (w) 

 of the ramus. The muscle of the ramus {20) is inserted on this 

 process. 



The basal surface of the bulb is inclined forward considerably in 

 advance of its connections with the rami (fig. 42 C), and a membran- 

 ous fold projects from it dorsally into the body cavity. In this fold 

 there lies a Y-shaped rod, the furcula (C, Frc, D), the arms of which 

 are connected with the base of the bulb, while the median stem curves 

 upward and posteriorly above the latter, and above the membranous 

 ninth venter (IXV). Upon the furcula are inserted a pair of large 



