78 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. IO3 



divides into two branches, one branch giving insertion to a group 

 of fibers arising posteriorly in the tibia {iiyb), the other, going on 

 into the femur, to a second group (H, iiya) arising posteriorly in 



Fig. 25. — The pretarsus. 



A, pretarsus of middle leg of drone, dorsal surface, flattened, inner sides of 

 claws uppermost, arolium turned upward. B, same, ventral surface, arolium 

 depressed and spread out. C, posterior claw of middle leg of worker, outer 

 surface. D, anterior claw of hind leg of worker, inner surface. E, pretarsus 

 and end of tarsus, claws removed, arolium turned upward, semidiagrammatic. 

 F, same, arolium depressed. G, ventral surface of fully depressed and flattened 

 arolium. H, arolium and manubrium, dorsal view. I, paper model of arolium 

 and manubrium in nonfunctional condition. J, same, illustrating flattening of 

 arolium by downward pressure on manubrium. 



95AP, tendonlike apodeme of muscle of pretarsus (retractor of the claws) ; 

 Ar, arolium; arc, arcus ; an.v, auxilia; mn, manubrium; 0, p, anterior and 

 posterior tarso-pretarsal articulations ; pin, planta ; Tar, end of fifth tarsomere ; 

 Un, claw (unguis) ; Utr, unguitractor plate. 



the base of the femur. The tension of the pretarsal muscle on the 

 unguitractor plate is distributed to the claws through the auxiliary 

 sclerites, and thus flexes the claws, for which reason the muscle is 



