INSECT ABDOMEN — SNODGRASS 



127 



muscles from the second valvifers (fig. 45 A, ig). These muscles 

 serve to deflect the distal end of the shaft of the sting, since their 

 pull is on points at the base of the bulb anterior to the articulations of 

 the latter (fig. 42 B, C, z) with the lobes of the rami. The role of 

 the furcular muscles in the mechanism of the sting has not generally 



ral details of the various parts of the sting of Apis vicllifica. 



Fig. 42. — Structu 

 worker. 



A, left first valvifer and proximal half of first valvula. 



B, anterior part of left second valvifer with ramus of corresponding second 

 valvula and basal part of bulb, showing articulation of the latter on the ramus, 

 and the ramus muscle. 



C, basal mechanism of shaft of sting and attachment of furcula. 



D, furcula. 



E, cross section of distal part of shaft of sting. 



a, articulation of first valvifer with ninth tergum ; b, articulation of first valvi- 

 fer with second valvifer; b', corresponding articular point of second valvifer; 

 c, attachment of first valvula to first valvifer ; d, d', groove of first valvula ; 

 e, insertion on first valvifer of muscle (/.;) from spiracular plate of eighth 

 tergum ; r, poison canal of sting ; ta, distal lobe of ramus of second valvula ; 

 x, connection between ramus and bulb of second valvula ; y, articular process 

 of base of bulb ; .cr, point of articulation between ramus and bulb of second valvula. 



been understood. Zander (1911) and subsequent writers have re- 

 garded them as protractors of the sting shaft ; but, as will later be 

 shown, the outward thrust of the sting is brought about by other 

 means, while simultaneously the shaft is depressed by the muscles 

 inserted on the furcula. 



The morphological nature of the furcula has been somewhat puzz- 

 ling to students of bee anatomy, but it is evident that the furcula is 



