NO. 2 



HONEY BEE SNODGRASS 



39 



sternum, their posterior articulations on the endosternal arms, and the 

 shortness of the occipital axis between their anterior ends (fig. ii B, 

 e), are well adapted to give partial rotary movements to the head by 

 a differential, or antagonistic, action of the right and left sets of 

 muscles attached on their anterior parts. 



The prothoracic leg muscles will be described in connection with the 

 structure of the legs. 



Fig. 14.— The antenna cleaner and the tibio-tarsal joint of the fore leg. 



A, left fore leg of worker bee, showing antenna cleaner at base of first 

 tarsomere (Btar). B, antenna cleaner open, anterior view. C, antenna cleaner 

 closed. D, tibio-tarsal joint with muscles exposed by removal of anterior wall 

 of tibia. E, base of first tarsomere with muscles, anterior view. F, antenna 

 cleaner of Halictoides calochorti Ckll. G, same of Vespula maculata (L.). 

 H, same of Tragus vulpinus (Grav.). I, same of Ortissus sayi Westw. 



a, closing lobe (fibula) of antenna cleaner; b, tarsal notch of antenna cleaner; 

 c, basal angle of notch ; d, distal angle of notch ; e, anterior lobule of closing 

 lobe; /, stop-process of tibia; m, tibial articular process; 11, tarsal articular 

 process. 



III. THE PTEROTHORAX 



The wing-bearing section of the trunk in the cHstogastrous 

 Hymenoptera (fig. 15) is composed of the three body segments that 

 are the mesothorax, the metathorax and the first abdominal segment 

 of other insects. Though the notal plate of the prothorax {N^) is 

 closely associated with the pterothorax, and looks like a collar on the 



